: Stutter, Engine or Trans?



Ranger
11-12-04, 01:06 AM
Well I guess it's my turn. '97 Deville. This afternoon I was on my way to work and as I was on the toll road entrance ramp I slowly accelerated from about 45 mph, not enough to downshift. I felt what I thought was a misfire. Somewhat like a coil breaking down under load. It still accelerated albeit slowly. When I got to work I put it in park and lightly brake torqued it and could not duplicate the symptoms. On the way home I tried it with a cold engine and all was normal. After normal operating temps were reached the same symptoms appeared. I thought maybe a weak fuel pump but WOT ran smooth though maybe not quite as much power. When cruising at 50 mph and a light throttle acceleration I can feel a pronounced stutter and hear an occasional pop or bang. Hard to tell for sure if it is coming from the tail pipe or under the car but I swear I can feel something bumping the floor board. I can also feel this stutter or slip when accelerating normally from a stop. I tried holding it steady and light brake pressure. No RPM jump. Once on a county back road with no traffic I stopped and brake torqued it again. This time I ran the RPM up to about 2000. At about 1600 I could feel an occasional stutter or slip again but I was standing still with my foot on the brake. I am starting to fear a transmission problem rather than an engine problem. Maybe this WOT stuff is not such a good idea after all. NO codes, temp normal 212f, no warning lights. What do you guys think?

Chairman_of_thebored
11-12-04, 08:36 AM
I too had the same problem with my SLS running fine at times but missing/stuttering at driving speeds. It would give a little slip right when you take off, made me wonder if the tranny was slipping for a second. It got more noticeable as the car became warmer. Pulled all the plugs, they looked great. The problem was that the wire caps were not down all the way on the plugs on 2 of the back cylinders. I guess as it warmed up, the expansion caused the bad connection. Reseating them got rid of the problem. My plugs and wires were only 30K old, so I didn't think they were the problem, but sure glad I checked. Good luck!

Jim from WY

Andrew M. Franklin
11-12-04, 08:51 AM
I have this same problem with my '94 N* and described it on this forum several weeks ago. Was counselled to check the EGR ports in the spacer plate between the head and intake manifold - I guess these can clog and cause poor part-throttle cruising performance. I thought it at first kind of felt like the TC was switching in and out of lock or something trans-related, but advice from some excellent forum members directed me toward the EGR ports first. Don't know if this applies to your year vehicle. I haven't done the work on my car yet, but will this winter. Please post your experience. Sincerely, Andy.

Ranger
11-12-04, 12:41 PM
In the limited time I have before I have to get ready for work I was able to pull the front plugs and one of the rears. Most of the platinum tips were gone and the gaps were .060 or close. I cleaned them and regapped them. If that was the problem 5 out of 8 should make a difference and I'll replace them all ASAP. I'll report my findings when I get to work. Looks like I'll have to remove the ignition module and coils to get at the last 3. The one thing I found though was that the manuals (owners and shop) both call for 41-900 plugs and I found 41-947's in there. ???

Ranger
11-12-04, 05:08 PM
Well, there was no change. It really has me confused. When I start from a stop it feels like the tires are slipping as if on patchy ice (slip, grab, slip, grab) which make me think trans. When I am at cruise and I lightly press the throttle it will studder or chuggle and and I can hear and feel an occasional pop or bang that sounds almost like a backfire which makes me think ignition. When I get on it hard it seems to run smoother. Maybe I'll change all the plugs to eliminate that and see what happens. This really has me baffled.

eldorado1
11-12-04, 07:28 PM
Isn't there a manual override code for the tranny pressure? You could just tell it to put on max pressure, and see if it stops slipping... That would rule out clutch packs at least. But it sounds like you have multiple problems.

Chairman_of_thebored
11-12-04, 11:25 PM
Ranger - How old are the plugs and wires? Did the plugs look like they were burning o.k? Light Brown / tannish coating? It could be a coil pack.

Ranger
11-13-04, 12:54 AM
Plugs and wires have 92K on them. They did not look too bad other than what was described. Coil are another possibility I'll have to check out along with the wires. They were untouched til the fuel rail replacement a couple of weeks ago. .

I just got home from work and noticed another symptom. I normally run 1950 RPM @ 70 MPH. Tonight I was running about 200 RPM higher with minor fluctuations Also I could not feel the normal TCC engagement at 41 MPH. I am starting to suspect the TCC.

Ranger
11-13-04, 12:13 PM
Making progress. I just went out in the garage and misted the wires (though I did not remove the conduit that the dealer put on) and coils. Nothing, engine was as smooth as a babies bottom. Then I did a brake torque with the hood up so I could watch the engine. Brought it up to about 2000 RPM and held it. It began to shudder a little bit (not real bad). I held it and let it continue for a few seconds. Then I noticed the SES light on. Sure enough there was the P0300 code. So I think I have it narrowed down to ignition, not tranny. Needless to say I am feeling much better about this. I picked up a new set of Delco 41-950's this morning so I will tackle the plugs tomorrow morning before work and eliminate that.

bigred
11-13-04, 01:01 PM
Brake torquing this powertrain, especially when it's hot, is not conducive to long transmission life. Stop doing that! :D

The thump in your floorboards is from the engine/transmission mounts. I totally agree your problem is almost certainly ignition. Hopefully the plugs will be all it takes.

I wonder what the dealers are doing that screws up our ignition systems on these fuel rail recalls. Yours is the fourth car I've heard develop this problem soon after the recall. I wonder if some of the plug wires get really bent enough to cause stress fractures in their conductors.

Ranger
11-13-04, 04:32 PM
I wonder if some of the plug wires get really bent enough to cause stress fractures in their conductors.
That is one of my suspicions. I'll know more after I change the plugs.

Chairman_of_thebored
11-13-04, 10:38 PM
With 92K on the plugs/wires, it would be a good thing to get out of the way. I'll bet it helps in one way or another. Please keep us abreast of the progress.

JIM FROM WY :hmm:

haymaker
11-14-04, 12:29 AM
I needed to replace the wires on my N* at 70,000 miles. I could feel a miss or stutter and an occasional pop or low level backfire. The 0300 code was never set. The best I could figure was the spark was jumping from one wire to the other in a place where they touched each other or ran in parallel then traveled on to fire the wrong plug causing a slight pop or backfire. When I changed the wires it all went away. I did change the old plugs at the same time even though they still looked good.

As to a problem of missing or skipping caused by the ignition wires after the new S/S rail install, think about it. The wires are not replaced under the recall and if they are old you may have a problem of the spark jumping from the wires to the nice new S/S fuel rail and on to ground. The plug wires lay down on the rail in many places. That means many places to ground the old wires. Remember the old fuel rail was plastic and the intake is plastic about the only metal the wires used to touch was the valve covers and now they touch the metal fuel rail. I didnít have any plug wire arcing problems with the new fuel rail because my wires are new.

Ranger
11-14-04, 04:41 PM
Well I changed the plugs this morning and I am glad to say she now purrs like a kitten and runs like a Thoroughbred. I have never seen a bad plug or plugs give such conflicting symptoms. As I said, I always think the worst. Gotta stop doing that. I think it is partially due to spending too much time here . Out of 8 plugs only one had a slight remnant of a platinum tip. In fact, most were slightly eroded where the platinum tip had once been. All gaps were in the .060 range. I can now feel the torque converter lock up again at 41 MPH and RPM at 70 MPH is steady at 1950 RPM.
Thanks to all for the help, suggestions and moral support. Oh yeah, and apologies to the dealer for what I was thinking.

Haymaker,
When the dealer replaced my fuel rail, they also installed plastic conduit on the plug wires to prevent shorting out on the new rails. I think that is part of the recall as I have heard others mention that as well.

haymaker
11-14-04, 05:12 PM
They didn't on mine.

Ranger
11-14-04, 05:44 PM
They didn't on mine.
Maybe they figured you'd never be the wiser. I thought my dealer was just being nice and extra thorough til I heard others mention it. See what others say, then maybe go back and ask if they forgot something.

jsantang
11-15-04, 12:11 PM
Had exact same symptons on my 92 eldo awhile back. Terrible bucking and stalling at varying engine loads. The problem was loose Positive battery cable connection to starter. My guy tightened up the nut on the starter with a long socket extension and that was it. and he did it for free!!! Most honest mechanics in all of Queens/Nassau, NY Union Tpke and Lakeville road, Lake Success. Love those guys..

Ranger
11-15-04, 04:37 PM
Well, it appears I spoke too soon. On the way to work this afternoon I got the same stutter, chuggle, misfire in the exact same location on the exact same ramp as were it first started. I is intermittent however and I was unable to duplicate it later. I suspect there are demons involved here. About the only explanation I can come up with (other than demons) is that when I changed the plugs, I jostled the wires and temporarily fixed the misfire.

Ranger
11-16-04, 02:51 PM
I checked the resistance on my plug wires. First let me say (again) that electrical is not my strong point, so if I say something stupid, be gentle. Here are the readings I got with the DVM set at the 20K setting.
#1 2.01K
#2 2.87K
#3 1.46K
#4 3.00K
#5 1.07K
#6 2.99K
#7 1.39K
#8 2.67K
Do these readings look ok? If so, the next step has to be a coil. The mis seems to me intermittent and more so when up to operating tempurature. Can a coil be intermittent? Also, the '97 service manual says on page 6-428 step 9, after locating a misfiring plug, check the resistence on that cylinders wire and it should not be above 15K. If I move the decemal over one place, most of mine are above 15K! Does that mean most of my wires are bad?

Also, are GM coils all the same? If the wires appear to be good, can I swap a coil from my wifes '96 Bonneville 3800 series II to eliminate a bad coil?

Ranger
11-16-04, 05:45 PM
Well, I just swapped the coils one by one with a coils I took from my wife's car. Same symptoms, so the coils are good. The only question now is what those readings from the wires mean. If I used the wrong setting and move the decimal over one place that would tell me all but 2 are too high. Can someone confirm that?

haymaker
11-16-04, 08:10 PM
One of the easiest ways to check you plug wires is in the dark. It would be a good idea to have a working flashlight on hand before you start the test. You will need a very dark location for this test to work. Remove the beauty cover, warm-up the engine, remove the under hood light bulb and turn off the headlights. Ask a helper to get in the car roll down the window and close the door (the interior light must be off). You will need to allow your eyes several minutes to adapt to the darkness otherwise this test will not work. Stand by the drivers side fender with the hood open, ask your helper sitting behind the wheel to start the engine and try to duplicate the conditions that cause the engine to miss, skip or stutter (never throttle up against the torque converter). You must keep your hands, head and clothes clear of the engine. If you plan to ask the helper to place the car in gear, never place a foot in front of the tire or you body in front of the car. Change the viewing angle to insure you have seen every wire over its entire length including the coils. You may need to go around to the passenger side to gain another viewing angle, but never stand in front of the car. The test should include engine at start-up in park at idle, off idle, 1,000 rpm, 1,500, 2,000, 2,500 rpm. Then block the rear tires and ask your helper to hold the brake firmly and place the shifter in drive then test at idle, off idle but never against the torque converter. I realize the helper canít see the tachometer to change to different rpm levels but itís ok to guess. Just remember there is no need to race the engine at a high rpm for this test to work. Just ask the helper to hold each one of these rpm levels for five seconds or so. It will be quite evident if any of the wires are leaking.

I have found this to be a cheap yet effective test and best of all, no special tools required.

Ranger
11-16-04, 10:32 PM
Idle seems to run smooth. The dealer installed plastic conduit on all the wires so I doubt they are "leaking" unless it is behind the right bank where there are none. I seem to get this mis (at least this is when it's noticeable) at about 40 MPH or better under light loads. That is when the TCC engages so there is more load on the engine. WOT or harder acceleration seems to run ok or at least is not noticeable. The only way I could duplicate it one time in the garage was brake torquing it to about 2000 RPM and holding it there. I don't want to do that again but at least that tripped the SES light and set a P0300 code so I new it was ignition related. I suspect plug wires but don't want to throw parts at it til I am sure those readings confirm it.

haymaker
11-16-04, 11:11 PM
If you can find the time give the test a try. It may supprise you.

eldorado1
11-16-04, 11:15 PM
I'd have to agree... pull off the conduit, and do the Bbob test - mist them with water in a dark place (careful not to fall or touch anything). I bet you'll see all kinds of arcing. Plug wire resistance just tells you that it's not completely broken inside. Doesn't tell you if it's shorting out externally to something (which is a problem with 50,000+ volts)

haymaker
11-16-04, 11:35 PM
I used this test for a little over 40 years and it has never failed to date.

mastertech
11-18-04, 08:57 AM
Ranger, sorry it took a while to respond, I've been jammed up at work. It sounds like you need a set of plug wires. Factory wires have that conduit around them already, so if you didn't have any on yours, it's very likely someone changed them before. Sounds like the tech was doing you a favor at the dealer, since that isn't part of the recall. One way to tell for sure is look for corresponding cylinder numbers on the wires themselves. If they are not numbered, they have been replaced. Also make sure there is no carbon tracking on the new plugs you have installed, as evidenced by black lines that resemble cracks on the porcelain insulators. Also, be sure to stick with ACDelco wires, as I have seen pretty crappy aftermarket ones. I know they cost an arm and a leg, but you will only have to replace them once. Good luck, and let me know how that turns out.

Ranger
11-18-04, 11:51 AM
The wires did not have the conduit on them before the recall but do now. I noticed no carbon tracking on the plugs when I replaced them. The plugs do have the corresponding numbers on them so they appear to be OEM. I just pulled the wires one at a time and put a spark plug tester (screw driver with a light in the handle) on each wire and they never missed a beat (at idle loads) but the engine idled smooth as silk even on 7 cylinders while I was testing the wires so I think it was rather inconclusive. The problem occures more at heavier engine loads, ie: 45+ mph, TCC engaged and light throttle. Yesterday I swapped all 4 coils with one from my wife's '96 Bonneville and there was no change so I have effectively eliminated the coils. The only variables left are the cam shaft sensor, crank shaft sensors and the ICM but I am not sure what kind of symptoms they will produce. I am kind of leaning towards wires but cannot prove them bad and hate to throw a $122 set of wires at it only to find out that was not the problem. I'm getting frustrated.

mastertech
11-18-04, 02:52 PM
With 92K on your wires, I don't think you will be frustrated if you throw a set on there.
Common misfire concerns happen under engine load, and wires may not appear to be problematic. Crank and cam sensors tend to produce a stall, not an intermittent misfire. The ICM is similarly not a real candidate for an intermittent problem. Just my two cents, of course, but I've repaired many a vehicle with the million dollar wire set.

Ranger
11-18-04, 04:37 PM
OK, thanks much. That is what I was looking for. Based on your assessment I will order a set of Delco wires. I agree that they will break down under load and that is why my instincts tell me wires. The thing that bothers me is that when it happens I can go to heavier throttle or WOT and she seems to run OK then. I would think, more load the problem should get worse, no?

BeelzeBob
11-18-04, 10:57 PM
OK, thanks much. That is what I was looking for. Based on your assessment I will order a set of Delco wires. I agree that they will break down under load and that is why my instincts tell me wires. The thing that bothers me is that when it happens I can go to heavier throttle or WOT and she seems to run ok then. I would think, more load the problem should get worse, no?

Running at part throttle (like when you notice the miss) there is a lot of EGR going into the engine. This puts a lot of demand on the ignition system as one of the hardest ignition requirements is igniting the charge that is 18% EGR....so it puts a lot of load or demand on the ignition system. Going to deeper throttle turns off the EGR and even deeper throttle adds more fuel for power enrichment...both creating an "easier to ignite" mixture in the chamber. Sort of goes against common knowlege as most people expect full throttle to be the highest demand point for the ignition.

It is not unusual for an ignition breakdown to show up at part throttle on an engine running a lot of EGR and the Northstar runs a lot of EGR for Nox control and for fuel economy. That is one of the secrets of how to get good fuel economy with a large car....throttle the engine with a lot of EGR to reduce pumping losses and design the combustion chamber to allow repeatable combustion even with the high dilution ratios. The Northstar chamber has good incylinder motion to allow those high EGR fractions...but...the high EGR fractions need a good ignition system to get the fire lit reliably. So...it can cause a "part throttle" situation to be a high demand situation for the ignition system.

One other thing about part throttle operation like you describe that makes it more susceptable to an engine mis-fire....or maybe I should say it makes an engine misfire more obvious....is that the torque converter clutch is on at that point and that tends to magnify any engine instability. When you crowd into it the torque converter clutch will disengage and just the open torque converter will isolate a slight misfire making it seem to disappear or get less noticeable.

You can use some silicone di-electric grease in the spark plug boots on the plug ends and on the coil ends to keep them from sticking and to help seal the boots to the towers and the plugs from moisture. The silicone grease forms a sort of seal that keeps the water out. Just be sure to not put too much as you need some friction of the plug boot to hold the plug wire firmly in place onto the plug so that the little umbrella built into the plug boot seals against the cam cover to prevent water from flowing down into the spark plug well. Look in the electrical section of most any autoparts store for the di-electric grease for that use.

Be aware that if a plug boot was leaking and allowing some arcing it may have carbon tracked the plugs even if they are new. If you replace the plug wires it would be a good idea to remove the plugs as you do the wires and wipe the insulators clean and inspect carefully for carbon tracking. Do the same with the coil towers.

Ranger
11-19-04, 01:22 AM
Thank Bill. You confirmed my suspicions and quelled my doubts. I now am sure I did the right thing when I ordered the wires earlier today.

first sts
11-20-04, 12:38 PM
Replace plug wires,plugs and get a coil pack from the junk yard see if this helps. My plug wires went bad and the voltage would go to other areas of the engine block causing all sorts of codes even some codes for suspention of all places,once the wires were replaced ALL my problems went away. See if you can get 8mm wires.
My coil pack went bad 6 months after replacing the wires.......
Now all I need are rear lights mine have cracked

Ranger
11-20-04, 05:01 PM
My wife just called me (at work) to tell me the wires were delivered today, somewhere between 1200-1500. WOW! Rock Auto is fast. I ordered them Thursday evening about 1700. I wasn't expecting them til next week. I will be installing them tomorrow (Sunday) morning and I'll report back when I get to work.

Ranger
11-21-04, 04:56 PM
Replaced the wires this morning. That was the problem. She is once again purring like a kitten and running like a Thoroughbred. Thanks to all for the input and support.

I was not aware that Delco wires come with a lifetime warranty to the original purchaser for as long as you own the car. Also getting all the conduit and clips back on in the right place was a bit of a pain but all's well that ends well.

highonchai
01-12-06, 10:57 PM
My '96 SLS is having the same exact problem. She only has 69K on her, just had the recall done like everyone else, just put a new EGR valve on. The TB does stick, it's just been too cold to clean it. But it looks like ill be buying a new set of wires from Rock Auto, especially since i just got a 5% off code in my e-mail... here it is, they say i can give it to my friends and family, so: 357479335543. My only question is: should i buy new plugs as well? i looked them over and they seem ok. Thanks a million for all the detective work Ranger!!! a lifesaver! Im so relieved to hear that its not trans or anything too serious, I just dont understand, at under 70K? Its obviously a flaw in the recall procedure that GM not only doesnt know about, but is also banking on with all the people going back to the dealerships with this problem and paying to have it fixed. But we can do the work ourselves without the general looking over our shoulder while sticking his hand in our pockets. oh well, Thanks again!!

Ranger
01-12-06, 11:18 PM
The reason it happened is that when doing the fuel rail recall, the plug wires must be moved out of the way. I guess after many many heat cycles, disturbing them does something detrimental to them internally. What, I am not sure. All I know is that it is a very very common phenomenon.

When I pulled my plugs, about half where missing the platinum tips. Many people have gone twice your mileage on them. You'll have to be the judge.

highonchai
01-13-06, 03:31 PM
Well i decided to order plugs as well, then i wont have to worry about the plugs or the wires for as long as I own this car. Again, Thanks!

dkozloski
01-13-06, 05:01 PM
The center conductor of stock ignition wires is a distributed resistance in the form of glass fibers and carbon dust. This is to reduce radio noise. Over time the glass fibers fracture. Now the spark has to jump a gap inside the insulation. As the spark jumps it gauses burning of the carbon dust and insulation. Vibration redistributes the dust and the problem becomes intermittant. New original equipment wires are the answer to most intermittant problems. Ignition wires with solid center conductors can cause unacceptable radio noise. Disect old ignition wires and you will marvel that they work at all.

samm
01-13-06, 07:06 PM
yes, this problem is exactly what i am trying to figure out on my 99 SLS. i tried the arching test but i only looked for a little bit, probably not enough to notice any arching. but with a squirt of water from a spray bottle it becomes much more obvious, right?
also, is my 99 SLS included in that fuel rail recall? it would be kinda cool to have an SS rail. i think mine is nylon...

Ranger
01-13-06, 07:19 PM
Yes, you have the right idea with the spray bottle. Do it in as dark of a place as possible.

The fuel rail recall is for '95 - '97 only ...... so far.

cdmcm
03-04-06, 12:24 PM
Ranger, I just got thru reading your post and all of the replies on your stuttering problem in June 2004. What did you finally determine the cause of it? Please reply because I am having the same problem on my 94 concours.

cdmcm
03-04-06, 02:44 PM
Ranger, sorry I thought I had read all of the replies, but I had not. I see where new ignition wires did the job for you. Didn't help on mine. I replaced with ac/delco wires. Only have 20,000 miles on the platium plugs. My mechanic checked out the coils by replacing one with a new one and on down the line and they checked out ok. I had a P071h code(intermittent MAP signal), so I had the mechanic replace the MAP and reground all the grounds. The car runs fine at idle speeds, only have a problem when I push down on the acelarator and the car is under a load. It seems to be worse when it gets warmed up. I am really at a loss on what to do now. Do any of you guys think it could be the Idle Control Value? Any comments will be greatly appreciated.

Ranger
03-04-06, 05:15 PM
No, ISC valve should have no effect on your problem. Sounds like either a coil, plug or wire is breaking down under load. Check the resistance of each wire. Maybe one went bad. Like wise with the coils & plugs. I would have him put it on a scope and check them under a load. Also check fuel pressure, though it sounds like ignition. Check the EGR as well, though I would not think that would cause the problem you are experiencing, but can't hurt to clean it.

cdmcm
03-08-06, 03:02 PM
Ranger, I took my car to another automotive garage and they put it on a scope and detected 4 bad plugs. They had the carbon crack in the porcelin part of the plug. Runs gread now. I was really upset with my original mechanic that he couldn' or didn't detect bad spart plugs. In his defense the plugs only had a little over 20,000 miles on them, but I would have thought he would have checked them out when I had the new ignition wires installed.
Won't be taking my cars back to him. I have been a customer of his for about 15 years. Thanks for your help.

eldorado1
03-08-06, 03:27 PM
Not all garages are equal when it comes to the tools they have at their disposal...

btw, what kind of plugs were they? Bosch +4's? :rolleyes:

Ranger
03-08-06, 05:27 PM
Glad you got it straightened out. Plugs should have lasted a lot longer than 20K but once carbon tracked, they are toast.

cdmcm
03-09-06, 02:38 PM
The plugs were A/C Delco.

dad
03-09-06, 03:38 PM
I have a 94 Seville 80,000 miles with the same problem outlined in all the post..except I have had plugs and wires changed and problem still exist. My mechanic says he used quality replacement parts and is puzzled by the problem. There are no error codes being produced. He has thrown in the towel. I just read all the posting on this issue and joined this forum to get some advice before I start throwing more money at this problem with no solutions. I have only had this car a year and not really sure on other repairs of Maint.

here is the problem.....at 42 Miles per hour (rpm about 1300) just after engine shifts from 3th to 4th it will studder. If you increase engine rpm or speed up to 48 it will go away. If you tap brake during occurrance, trans will shift out of lockup and rpm will increase momentarily and studder goes away until it shifts back to 4th. Engine runs perfectly below 180 degrees.

So ...question of the day, what does computer change at 180?

dad

Ranger
03-09-06, 04:18 PM
Define "quality replacement parts". A/C Delco, OEM plugs and wires?

eldorado1
03-09-06, 04:37 PM
here is the problem.....at 42 Miles per hour (rpm about 1300) just after engine shifts from 3th to 4th it will studder. If you increase engine rpm or speed up to 48 it will go away. If you tap brake during occurrance, trans will shift out of lockup and rpm will increase momentarily and studder goes away until it shifts back to 4th. Engine runs perfectly below 180 degrees.

So ...question of the day, what does computer change at 180?

dad

Hi Dad! :histeric:

I'm thinking you have a transmission or TCC shudder. Are you due for a tranny fluid change? Are you sure it's the shift from 3rd to 4th that has the shudder, and not the "shift" from 4th to TCC lockup? I know it can feel like an extra gear.......

dad
03-09-06, 07:53 PM
I think it is the shift to trans lock up or what might be overdrive...?? If you hit brakes
it disengages, and rpm rises..

I have not gone down the transmission trail yet.. although 2 trans guys did say they thought it was the engine...??

as for quality replacement parts?? good question. I will find out

dad

eldorado1
03-09-06, 09:12 PM
The thing about TCC lock up is it will magnify any problems you have with the engine. It will turn a slight miss into a car shaking ordeal.

Ranger
03-09-06, 10:07 PM
The thing about TCC lock up is it will magnify any problems you have with the engine. It will turn a slight miss into a car shaking ordeal.
Yup, that's what made mine more noticeable at light throttle above 41 MPH.

dad
03-10-06, 08:09 AM
so if it is the transmission lock up.. what do I do about it?

Ranger
03-10-06, 04:41 PM
What he is saying is that the TCC will magnify the misfire once engaged. The solution it to fix the misfire if indeed that is the problem.

dad
03-13-06, 08:10 AM
Ranger,

the replacement wires were Delco equal, according to my mechanic. He also said something about a PROM but not being shure he did not want to head in that direction? What is that?

What is significance of the fact it runs fine below 180 degrees and when warmed up it then starts its dance?

eldorado1
03-13-06, 12:16 PM
TCC lockup may not be enabled below 180? I don't know

Ranger
03-13-06, 02:09 PM
Ranger,

the replacement wires were Delco equal, according to my mechanic. He also said something about a PROM but not being shure he did not want to head in that direction? What is that?

What is significance of the fact it runs fine below 180 degrees and when warmed up it then starts its dance?
PROM is the PCM I think (Programmed Read Only Memory or something like that).
Not sure about the significance of the temperature. :confused:

dad
03-13-06, 08:52 PM
Ranger,,

I did the inspection in the dark routine, and misted the wires on my NEW wires. I did get a mini light show at low rpm. It was intermittent and decreased with rpm.. was it supposed to be zero dark.. or are a few streaks ok??

dad

Ranger
03-13-06, 09:58 PM
I do not believe you should get any "streaks". That would indicate wires "leaking". I forget the term but a glow of sorts is ok. What your seem to be describing seems to be bad wires. If the replacement wires were Delco, they are warrantied for life if you have the receipt.

eldorado1
03-13-06, 10:18 PM
I forget the term but a glow of sorts is ok.

Corona.

:thumbsup:

dad
03-14-06, 02:01 PM
Ranger,

while I was doing the dark test and checking wires last night I noticed that I could not maintain a steady idle with pressure on the gas pedal. If I tried to hold a 1000 RPM, the engine raced to 1500 or so and bounced up and down and the petal moved by itself. Could this be a TPS problem that is showing up and causing my studder at 40? Any way to check a TPS?

As for the dark test... there really was no arcing between wires, but what I noticed was the light following the wire from coil to plug. thus the streak.. do you think the wires are bad? This occured at low engine idle and about every other wire...it incresed in intensity when I misted them?

dad

Ranger
03-15-06, 05:08 PM
I am not sure but I would not associate RPM fluctuation with bad wires. Maybe TPS, ISC valve, vacuum leak, dirty TB.

If you are seeing an arc rather than a corona (thanks eldorado1) then I would suspect the wires. How old are yours?

eldorado1
03-15-06, 06:19 PM
You won't see an arc between wires... You'd see an arc between the wire and a ground, like the heads, valve cover, intake, brackets, whatever.

I believe autozone can test TPS sensors.

dad
03-15-06, 07:54 PM
eldorado.... the wires are new.. the question is how good are they? the garage that put them in,, says they were from auto zone? When I told the mechanic about the fluctuation in the rpm.. he said maybe try the TPS. I pulled wire on TPS, ran car up 60 with no shutter, probably becase it never shifted into overdrive...with TPS inop I could get RPM to stay stable while pressing on pedal. I reconnected it and could not get it stable,, plus pedal was being pulled down as rpm ran to 1800 or so

For 30 bucks I plan on installing the TPS and see what happens

dad

blunted
03-16-06, 03:50 PM
If they got them at Auto Zone, I can guarantee they are not Ac-Delco wires. Go put in the Delcos and see what happens, I've read alot of posts where people use Bosch or other aftermarket wires and get all kinds of weird issues.

eldorado1
03-16-06, 04:39 PM
I've got the $40 autozone special wires on mine, and have sprayed them with water on one occasion and saw no corona or discharge (or change in idle quality). They're going on 2 years now, so I'd say I got my money's worth out of them. ;)

dad
03-16-06, 07:46 PM
well I changed the TPS and no joy. When the temp reaches 180 the dance starts. I am still reluctant to change wires but unless I hear more suggestions .. that will be my next step... 120 bucks for ac and cross my fingers

dad

Ranger
03-16-06, 08:01 PM
FWIW, I would not expect wires to be temperature sensitive. Mine weren't. What have you changed so far?

dad
03-16-06, 08:37 PM
I have changed plugs and wires and today the TPS. I keep bringing up the temp because the car runs fine until temp hits 180. Its like an on off switch. When cold it shifts fine and passes from 4th to od without the studder. Once hot, at 42 mph thru 46 it studders. What does the computer tell the engine to do at 180? coils all check out. The other odd thing is that the mechanic says he gets a -24 reading on the spark advance. Whatever that means. I was with him and he had meter attached to system.

If its wires how come they do not malfunction below 180?

Dad

eldorado1
03-16-06, 09:33 PM
So how long does it stutter? Forever if you're between 42 and 46mph? It it just for a second or two?

Ranger
03-16-06, 09:49 PM
Based on what you are now saying, I seriously doubt it is wires. It has to be something with that magic 180 degree factor. Maybe ewill3rd will chime in. I am lost but a FSM would be a help at this point. It's times like this that you really miss the old guru.

dad
03-17-06, 06:58 AM
here is problem again..

with temp above 180, you proceed with a normal acceleration speed, it goes thru the gears, at 42 it shifts to 4th and studder starts. RPM is about 1300. It will continure as long as you stay in that 42-45 with that RPM. If you tap brake pedal, trans lock up kicks out the overdrive and the rpm rises and it momentarliy goes away, if you hold stready speed, lock up kicks in and it returns. IF you go thru the shudder, keep accelerating RPm gets to 1500 you cannot feel it and the speed is now 50 or so.

thanks for the help

eldorado1
03-17-06, 09:09 AM
Okay, so basically you have a low rpm miss. Have you checked for codes? You said you replaced plugs and wires, correct?

It really sounds like an EGR issue. There should be an enable temp, but I kind of doubt it's as high as 180. If you want to give it a shot, it will cost you about $5 worth of carb cleaner, an old toothbrush, and about an hour's worth of your time...

What you have to do is remove the 4 recessed bolts on the center of your intake, and move the intake to the side. Under the intake are 2 phenolic spacers. You need to clean those with something like simple green and that toothbrush. Be careful not to damage the seals, because they are reuseable if they're not damaged. Don't use the carb cleaner here, because it might damage the phenolic resin.

Next you need to clean out the EGR passages on your heads. For this you'll need that carb cleaner and you'll probably want to stuff rags in each cylinder port to prevent crap from falling in. You also might want something a bit stronger than a toothbrush to begin, like a flat blade screwdriver. You've probably got 1/4" of carbon buildup in there now. After you get that all scraped out, you need to work on the "mouse holes". These are little slots that go from the large passages to each individual port. They're no more than 1/8" wide. Just use that screwdriver to free the carbon.

It's a lot of work, but it's cheap. I'd have to say it's likely it's causing or contributing to your problem too. Especially if it is over 100k and the egr hasn't been serviced yet.

dad
03-17-06, 08:18 PM
I did the erg clean about a week ago and no change... it was not that dirty,,, i cleaned off the little crud that was there,, rinsed with wd 40, dried all and put back togethre. I scraped the out let and clened the ports with a knive and screwdriver.

I have 85000 on this beast..what next?

dad

eldorado1
03-17-06, 09:43 PM
You may have mentioned this already, but do you have any codes?

Next I would mist the ignition module and coilpacks to see if there's any arcing there, or see if it changes idle quality.

dad
03-18-06, 08:55 AM
eldorado

In reply, I am getting no codes. My mechanic has done all the electronic checking with his equipt

and he can not get any either.

I have not done the clean the throtte body but willing to do.

I have done the check wires in the dark routine, and at that time misted the wires and coil pack. I did not see any arcs but did experience streaking, where i saw the bolt of energy follow the wires from coils to plugs. I am not sure is this is normal. They did not seem to be grouding out anywere and its hard to tell if its actually missing. I did this test at 1000 and 2000 RPM.

I know I have been chasing this electronic bug for a while,,but do you think its possible that a cv joint or motor mount could be giving me the shutter at that exact load and rmp configuration.?? I say this because about the time this problem started I also picked up a front end noise and its not going away either.

Dad

eldorado1
03-18-06, 10:29 AM
cv joint - no

motor mount - possibly

It could exaggerate any miss that you have. What you could do is with the hood open, and engine running, have someone put it into reverse while you watch the engine. Ideally it won't shift around much, but if you see it flop 2", then you have a mount problem.

I'm kind of surprised there are no codes, not even history codes. I think you need to run through the code checking procedure to see what you can dig up.

gorky
03-19-06, 09:24 AM
My '96 SLS is having the same exact problem. She only has 69K on her, just had the recall done like everyone else, just put a new EGR valve on. The TB does stick, it's just been too cold to clean it. But it looks like ill be buying a new set of wires from Rock Auto, especially since i just got a 5% off code in my e-mail... here it is, they say i can give it to my friends and family, so: 357479335543. My only question is: should i buy new plugs as well? i looked them over and they seem ok. Thanks a million for all the detective work Ranger!!! a lifesaver! Im so relieved to hear that its not trans or anything too serious, I just dont understand, at under 70K? Its obviously a flaw in the recall procedure that GM not only doesnt know about, but is also banking on with all the people going back to the dealerships with this problem and paying to have it fixed. But we can do the work ourselves without the general looking over our shoulder while sticking his hand in our pockets. oh well, Thanks again!!

hey guys,
did anyone else buy from Rock Auto more recently? this discount code is no longer valid, probably because its been too long ago. their prices do seem very reasonable though even without a discount.

93greeneldo
03-25-06, 01:45 PM
After reading this thread it helped my find out what was wrong with my 1995 aurora. Ever since I bought it 3 months ago around 40-45 mph it would shake and shudder so bad I thought the car would shake to pieces. I was looking into a torque converter or transmission until I read this thread and looked at my ignition. I was taking it for a test drive when I took a corner and all of a sudden the slight miss turned into a big miss and I couldn't maintain 30mph. Got it home and it turns out I lost not one, but Two coils in my car. Spent 46 dollars on new coils and the car runs better than I could even imagine. Now it revs smoothly and quickly. Isn't as fast as my 1998 eldorado but definitly fast enough to make me happy for a winter car. Thanks to everyone who commented and added to this thread, the help here is priceless. Jeremy

eldorado1
03-25-06, 02:01 PM
Got it home and it turns out I lost not one, but Two coils in my car.

Wow! That's very unusual!

gorky
04-10-06, 08:38 PM
well I spent the $170 at Rock Auto for the AC Delco plugs and wires and its still stumbling like crazy.

good thing is they gave me a discount code that anyone can use before June 6th to get 5% off: 405013377335

bad thing is the parts didnt fix my problem.

what's the next most likely culprit, coils, or the little assembly that the coils plug into?

or should i hunt down the wiring between the controller and that coil assembly?

I was really hoping . . . . . . . .

but it was probably time to change them out anyway

Ranger
04-10-06, 08:49 PM
Wow! This thread is sure getting some mileage. Sorry to hear the plugs and wires didn't help. Get a stethoscope and listen to each coil. If you hear any arching, replace it. The other alternative that I used to rule them out is to switch them out one at a time with a known good one. I swapped one out of my wife's Bonneville. The miss was still present with each one I swapped, so I knew the coils where good. Also use the stethoscope to listen to each injector to be sure you hear it operating. If one is silent, there is a problem with the injector or the wiring.

93greeneldo
04-11-06, 08:54 AM
Whe I had to test my coils, me mechanic to me to pull all the plug wires off the coils and then have someone crank the car while you stand back and look at the coils. My mechanic warned me to keep my entire body away from the coils when you did this because if one of those arcs hits you it can put you in the hospital so be careful. Their should be an arc between each individual coil pack. If not, there are two bolts, one at the top and one at the bottom that hold the coild on to the ignition control module. I swaped out the bad coil on the car with a known good one on it so I could make sure that it was not the ignition control module. Coils are pretty cheap, about 50 bucks each, the ignition control module on the other hand is between 200-300 dollars. Hiope this helps, jeremy

gorky
04-11-06, 07:01 PM
Thanks for all the advice guys.

At least these items are relatively inexpensive.

with 140K miles it was probably time to change them anyway.

i'd rather put the money into parts than pay for labor anyway.

i've bought one new coil and will try your pull out all the wires test.

if that doesnt work than its onto the module

Thanks again,
gorky

eldorado1
04-11-06, 08:17 PM
Thanks for all the advice guys.

At least these items are relatively inexpensive.

with 140K miles it was probably time to change them anyway.

i'd rather put the money into parts than pay for labor anyway.

i've bought one new coil and will try your pull out all the wires test.

if that doesnt work than its onto the module

Thanks again,
gorky

The spark will not jump between the coil towers. The maximum you'd see it jump is about 1". I doubt you'd see more than a 1/2" spark on a good day. Forcing it to jump larger distances will make it try to find other ways to ground, usually by trying to break down internal insulation. If you must do this, wrap a paperclip around one of the terminals and have it pointing 1/4-1/2" away from the other terminal.

93greeneldo
04-12-06, 11:27 AM
No, the spark WILL jump between the coil towers. The coils are rated for over 40,000 volts and that is more than enough to jump between the two coil towers. I know this because I have done it and seen it on my car. If it doesn't jump between the coil towers the coil is bad and needs to be replaced. If you make it easier for the coil to jump across even if it is weak it might jump across. If you ake all the wires off and have someone crank the car you will have basically mini bolts of lightning between the coil packs. They will be strong and loud. Do not put anything on the coil towers like a paper clip, if the coil is good it could make is so hot it could melt it to the coil and ruin it or you could make the spark jump somewhere else damaging something else.

gorky
05-04-06, 07:34 AM
you guys will never believe it.

i checked all the coils by swapping a new coil through all four positions, with no change in performance.

anyone want to buy an almost new coil?

but during this whole time, i had been noticing that my exhaust note seemed to be getting louder and louder. at first i didnt notice it because the northstar exhaust is rather throaty just normally. then even as it got loader over time, it was not unpleasant, it just made the car sound more aggressive. so i let it go all of this time. i finally got it looked at this past weekend. it turned out to be a small split in the seam of the catalytic converter. At 140K miles, I figured it was time to be replaced anyway, so i had the shop replace it.

STUTTERING FIXXED!

i'm sure the new spark plug and wires helped, but sealing my exhaust leak by replacing my catalytic converter did the final trick.

boy, the northstars must be really sensitive to back pressure.

packrat427
05-04-06, 08:51 PM
Ranger , you are expaining the same symptoms I chased for over a year ,I done everything ignition related ,even replaced the EGR valve ,and that covered it up for a week or so .
Try this, next time you get the chuggle , that is the same explanation I used ,
pull the shifter out of OD. and as the RPM's come up see if the problem goes away ,or you can accel a little more to get the TC. to unlock ,This problem only occured to me when the converter was locked and I was on a slight grade while travelling under 50 mph ,It all is related to plugged EGR passage in the heads ,and it is trying to pull egr vac all off 1 or 2 cylinders ,causing this.
And as for the torqing the engine in drive while holding the brake ,it will make the engine jump just as you explained ,and feel like a dead miss.
I wish you luck , I really do suspect that this you problem .:)

packrat427
05-04-06, 09:04 PM
I am sorry I did not read all the other post in between ,been up too long today ? 14 hours of work on 3 1/2 hours sleep .
Dad this one is for you too ^^ the seafoam will not touch it ,the EGR passages are too small and become so packed that they can only be effectivley cleaned by removing the intake and cleaning the passages in the head ,I think this becoming more of one of those problems ,that it creates so many other issues that is overlooked and mis-identified .
Once I did that ,the car was so much more enjoyable to drive, all the chuggle ,shudder,misfire,and other quirks were GONE !!!

Ranger
05-04-06, 09:11 PM
You must be very sleepy. Note that this thread was started 11/04. In my case it was in fact the wires that were the problem. That is buried back in one of the posts.

packrat427
05-05-06, 11:03 PM
I am really sorry about that ,I did not pay any attention ,this forum is much different from the one I Moderate ,This site is like a Cadillac compared most (LOL)and I was just not familure with it yet ,this site has so many different features and I was not paying attention to the thread #'s in that post , most newbies usually catch alot of flack for doing that in my forums,Thanks
And yes I was very very sleepy ...Doug

dad
06-09-06, 10:36 PM
Hey guys for what its worth.. this is how the saga of my studder played out...

I replaced the TPS after replacing wires and plugs to no avail. At first the new TSP did nothing. THen I remembered reading somewhere that to replace the TPS you should disconnect the battery first because it has a connection to the control module and remembers?? so a week later I disconnected the battery and the studder went away and mileage increased to 24 gpm highway and I am a happy camper.

now all I have to solve is the oil blue smoking issue

dad

digitalcaddie
09-04-07, 03:22 PM
OK...I'll jump in here and revive this post again. I've got a '97 SLS that has a P0300 code and is running rough due to that misfiring cylinder. I replaced all coil packs, but that didn't fix the problem so I returned the new coils and reinstalled what was in there. Next, I changed all plugs, but the problem is still there. I did the mist test last night on the wires and didn't see any lights, glows or coronas. Also the boots in my existing wires look good. I measured the resistance of them and they were 4k ohms on the short wires to 9k ohms on the longer ones. According to another post in here if the wire measures over 15k ohms, that's when you really need to replace it. So I just bought a $60 set of Duralast wires from Autozone. Yes, I've read that I should only get Delco, but the stealership (aka Cadillac of Naperville for you IL folks...don't take your car to these morons, I've heard Napleton is a more honest place) wanted $202 for a set of Delcos and I don't have time to wait on a set from Brasington (good people to deal with) or Rock Auto. The Duralasts have a lifetime warranty on them and if I can only get 20k miles out of them, GREAT. That'll be another year on a car that already has 150k miles on it that I only paid $3700 for in the first place (although I'd run the thing to 300k miles if it'll hold up). My question is, I measured the resistance on the new wires and they were about the same as what I have on there... ~9k on the longer wires to 4-5k ohms on the shorter ones, so what have you guys measured on new Delco wires? Ranger posted that the resistances on all his bad wires were sub 5k ohms, so mine appear to be in REALLY bad shape, but the new ones aren't much better. Let me know what you think. Now I realize that DC resistance which is what my DVM is measuring is not a dynamic measurement and these things are not going to be delivering DC current so maybe...well I dunno. I guess I'll install them and see what happens.

digitalcaddie
09-05-07, 09:49 AM
So new plug wires did not fix my problem. I'm stumped...anyone have any other suggestions?

digitalcaddie
09-05-07, 02:14 PM
Someone posted that a stuck EGR valve was the cause of their P0300. I took that off today and it wasn't stuck open or closed and wasn't that dirty, but I cleaned it anyway. That didn't fix my problem. Anyone have any suggestions??

digitalcaddie
09-06-07, 10:01 AM
So my problem was a clogged fuel injector. I called my mechanic and he said hold a flathead screwdriver against the body of the each fuel injector while sticking your ear against the end of the handle. Plug your other ear and listen for the click, click, click of the fuel injector. It sounds wierd but it was easy to hear the things working. If you find one that isn't clicking, tap it with the screwdriver handle or a small hammer or whatever you can get in past the fuel rail to try to clear the clog. That worked like a charm for me.

fleishman
09-06-07, 04:12 PM
Thank you for keeping us posted! I cant wait to listen to my injectors!

Ranger
09-07-07, 05:59 PM
Listen with a stethoscope if you have one. It is amazing what you can hear.

thewireman*
03-31-10, 10:35 PM
I know this is an old thread, but I finally bought some new AC/Delco spark plug wires and it stopped the shutter. Thanks guys!

Ranger
03-31-10, 11:09 PM
That's why this stuff is archived. Glad it helped you.

ewill3rd
04-01-10, 09:27 PM
Wow an oldie for sure.

I read some of this, only found it because someone said my name.

Something common to this type of problem on a high mileage N* engine is "carbon track".
I used to see it a lot on cars with plug wires.

Under heavy loads (cruise condition with throttle in 4th gear) it can actually become easier for the spark to come out of the top of the wire and then shoot through the boot to the base of the plug to ground rather than jump the high pressure gap in the combustion chamber.
Every time this happens the arc leaves behind carbon deposits, which make it easier and easier for the electricty to flow down the side of the plug.
This can be evidenced by small lightning bolt looking marks down the insulator of the plug when you remove and inspect it.
I have seen anything from a few traces, to half of the plug insulator being black. These marks will not rub off usually and if you see carbon track then you must replace the plug AND the wires affected (a set is adviseable).
If you don't, then the carbon track in the plug boot will cause a new carbon track to grow on the plug and you are back to square one.

Less common but possible is carbon track on the coil tower. It will jump from the tip back to the base of the module rather than go through the wire.

Just wanted to add that to this already good thread.

jones105n
06-21-10, 12:26 PM
well it appears i have hijacked an old thread but thought i would add my experience. 95 concours 4.6 running rough, stumble at takeoff and backfire at intake. wife reported SES on all the time. checked codes:

1) P036 EGR pintle out of range
2) P071 Intermittent MAP sensor

did several WOT's to help with P036. still had miss and stumble. fuel filter replaced (due for it) plugs replaced (also due) air filter (due) to no avail.

No more P036 or P071 for time being. Cleaned EGR and TB (follow directions in this forum) still to no avail. checked voltage at MAP it was correct. checked for vacuum leaks and had none replaced PCV (due) boot was cracked at valve and replaced it. still had miss and stumble. checked FPR it was bad replaced with delco kit. no dice miss still there. fuel pressure back to normal though.

Misted the wires sat. night and no arcing. started pulling wires one by one and found no spark at #4. this indicated bad wire or coil. had a set of wires in garage and used one to replace #4 and still no help so OBVIOUSLY has to be coil. pulled coil from the garage and replaced OE and VOILA back to running the way a N* should run. Hope this helps somebody. I now have no codes and an exceptional automobile again.:thumbsup: to all who post and reply here. rick