: Huge Problem, No Shop Can Fix!!!! Help!!!



HelpMyCadillacPlz
11-08-06, 09:56 PM
I recently purchased a 1998 Cadillac DeVille with about 60k on the Northstar engine. The last few months i've been having a strange, and very terrible problem. I will be stopped at a red light, and the engine will be ideling at 600rpm, then all of a sudden, the engine will shut off. It has always turned right back on when i pop it into neurtral and turn the key, but it is a serious problem. Sometimes after i get it started, if i'm still sitting at the same red light, it will happen again! I have taken it to three different shops (one of which was a cadillac dealer), and they all came back with the same response: "we drove it around for hours, and couldn't recreate the problem, so we can't help you". It doesn't happen all the time, but whenever i'm driving it further then 5 miles, it happens. When i purchased the car, there was an old cd changer installed, with an external remote wired in, but it doesn't work. I'm thinking it could be wiring causing the problem, but i really have no clue at all. It's a shame, this problem has made me not want to drive my new car anywhere. It sits in my driveway gathering dust because i'm afraid of breaking down at every red light i come to. If anyone, has any idea about what it could be, or if it has happened to them, i'd really appriciate any kind of response. Please. Please. Please. Help. I'm desperate.
Thanks.

Ranger
11-08-06, 10:29 PM
Have you checked the codes? I would think that the Caddy dealer would have though. What you are discribing is a classic crankshaft position sensor failure symptom. '99's are not known for this, but that does not mean that they are immuned. When one fails it will usually set a DTC but not always. It might be worth replacing both "A" & "B" sensors if you wnat to try throwing parts at it. Intermitent failures are a bitch to diagnose. They are located above the oil filter adapter, which needs to be removed to gain access to them.
You can get them for a good price (and fast shipping) here . http://www.rockauto.com

1badcaddy
11-08-06, 10:40 PM
Yep classic CPS going out. They are intermittent at first then it just won't start at all. Should be a str8 4ward removal and install. Good luck man!

CadillacSTS42005
11-08-06, 10:54 PM
Third vote on the CPS's

codewize
11-08-06, 11:17 PM
CPS's for the 4th time.

Who the heck are you taking the car to that doesn't know that.

GreenMachine
11-09-06, 12:00 AM
Not all shops are experts on Northstars, I would bet on the CPS's but when my 98 was suffering from later stumbles but at first an intermittent stall after it had been running and I come to a stop light plugs that were in really ugly shape was the culprit.

If you check your codes you'll most likely find the one for "Engine Stall or Near Stall detected"....or code P1599..doesn't always tell ya much but in the FSM there is a flowchart for it.

There WILL NOT be a check engine light on when this DTC sets. But when it is in history it will record all the data on the stall and will most likely point you in the right direction.

Here's a quick summary of that table:

1.
A. The tech working on the car should hook up a scan tool locate the stall data, it is not located in the Failure Records.
B. Map Sensor Display Taken at the time the stall occured should be checked, if its value is higher than 95kPa the problem is Fuel System, Idle Speed Control, Emissions System, Wiring and Connections, if true perform the Fuel System Check.

If not one of those, the tranny system and sensors (CPS included in that) should be checked. Ignition System grounds should be checked, anything that could send a bad signal to the PCM and cause it to "crash".

This code, although vague, points you in the right direction.

dp102288
11-09-06, 09:15 AM
CPS. I have read lots on how that kills the engine.

Love your username...

HelpMyCadillacPlz
11-09-06, 04:36 PM
Thank you! Since i have zero experience fixing cadillacs, i'm getting ready to take it to it's fourth mechanic, now armed with all of your expert diagnosis. As shocking as it is i'm pretty sure that all 3 places i took it, including the cadillac dealership did not check the codes. It's especially odd seeing as how insistant i was about finding and fixing any and all problems it may have had. I was basically standing at the counter, tapping my credit card against it, praying they would find a problem, which i have NEVER done before. Now armed with your expert diagnosis i am going to take it to it's fourth appointment. Do you think i should go back to the cadillac dealership? Or is the fact that they were so clueless about it the first time around, ample evidence that i should never bring it back there? Thanks again, i'll let you know how it goes.

EcSTSatic
11-09-06, 04:44 PM
Sounds like you should have brought it here first :thumbsup:

Ranger
11-09-06, 06:32 PM
In their defense, they can't fix a problem that they can't duplicate and I'd have to say that they are being honest by not throwing parts at it without proper diagnosis at your expense. Now if they did not run the diagnostics Which I would find hard to imagine), that is another story. Run them yourself and see if there are any DTC's stored.

HelpMyCadillacPlz
11-09-06, 09:50 PM
The only piece of equipment i own, came in the trunk, and is under the spare tire. My tire iron. Anyway, if it's not something i can run down to auto zone and buy for under a hundred bucks, i have to outsource it to even check the codes. Which i've decided is the next step. Be back with an estimate, hopefully.

chazglenn3
11-09-06, 10:15 PM
You don't need ANY tools whatsoever to run the diagnostics on the Cadillac. See the tech tips section of this website on how to check them yourself by pressing a few buttons. The procedure is at the top of the section in the "stickies". :thumbsup:

Tricky
11-11-06, 11:02 AM
A CPS is the last thing Id look at , sorry! Not my vote .
If the engine starts back up straight away and runs ok.
Reading your thread it looks as if the engine is idling too low and cuts out.??
Is your engine idle speed too low???

Dadillac
11-11-06, 12:06 PM
A CPS is the last thing Id look at , sorry! Not my vote .
If the engine starts back up straight away and runs ok.
Reading your thread it looks as if the engine is idling too low and cuts out.??
Is your engine idle speed too low???

Well when my crank sensors went bad, that is exactly how it acted. I would be driving and it would just quit. I would turn the key, and it would fire right back up. The crank sensors don't seem to fail permanently. They seem to have intermittent failure. I also vote on CPS. This is from experience.

Don

AlBundy
11-11-06, 01:11 PM
The only piece of equipment i own, came in the trunk, and is under the spare tire. My tire iron. Anyway, if it's not something i can run down to auto zone and buy for under a hundred bucks, i have to outsource it to even check the codes. Which i've decided is the next step. Be back with an estimate, hopefully.

You don't hafta go to auto zone to check your codes but a good thing is auto zone will do it for free so there's no purchase necessary.:thumbsup: I also vote CPS.

codewize
11-11-06, 02:35 PM
Don is correct here. That's exactly how they act. They start failing under higher temp then as soon as they're not in use they become stable again for a period of time.


Well when my crank sensors went bad, that is exactly how it acted. I would be driving and it would just quit. I would turn the key, and it would fire right back up. The crank sensors don't seem to fail permanently. They seem to have intermittent failure. I also vote on CPS. This is from experience.

Don

thydarkprevails
11-13-06, 05:57 PM
i'm going to agree on cps...i had that same problem in my old thunderbird supercoupe, granted it's not a cadillac, but the symptoms were exactly the same, the dealership couldn't figure it out, and neither could one shop i went to. i would even stall for as long as 20 minutes sometimes...as soon as i replaced the cps, i never lost power for the duration of the cars life

infin1ty
11-13-06, 10:03 PM
Do not rule out the fuel pump. Place a fuel pressure guage on the fuel rail and test for ~40psi of constant pressure. If you see it falter as the car stalls - your problem is identified.

jss
11-14-06, 12:17 AM
HelpMyCadillacPlz,

I don't know what's wrong with yours (probably CPS like everyone says), but I'll relay the story of what happened with my 94 Northstar.

It exhibited the exact same symptom as yours for a week and a half; so I started throwing parts at it. Because it was a classic sign of CPSs, and because they were only $35 each at O'Reilly's, I replaced both and saw no change in the problem. I then replaced the fuel filter and fuel pump and saw no improvement. About a week later she began running very rough and was subject to die anytime the engine dropped below 1000rpms. Two days later as I started to leave for work, the Seville decided that she wasn't going to go with me. I tried everything but bad language and couldn't get her to start.

I towed her to the dealer who told me that the CPSs and ignition module were bad and that for $1100 they would fix me up. It turned out that if they see no fire, they do no tests and simply replace the ignition system; hey, it's not their money! I towed her back home and replaced the ignition module; still no change. After running a plethora of tests, I replaced the PCM and she's run perfectly ever since.

Good luck.

codewize
11-14-06, 02:16 PM
Wow, I would think a bad PCM would cause more of different style problems. Interesting.


HelpMyCadillacPlz,

I don't know what's wrong with yours (probably CPS like everyone says), but I'll relay the story of what happened with my 94 Northstar.

It exhibited the exact same symptom as yours for a week and a half; so I started throwing parts at it. Because it was a classic sign of CPSs, and because they were only $35 each at O'Reilly's, I replaced both and saw no change in the problem. I then replaced the fuel filter and fuel pump and saw no improvement. About a week later she began running very rough and was subject to die anytime the engine dropped below 1000rpms. Two days later as I started to leave for work, the Seville decided that she wasn't going to go with me. I tried everything but bad language and couldn't get her to start.

I towed her to the dealer who told me that the CPSs and ignition module were bad and that for $1100 they would fix me up. It turned out that if they see no fire, they do no tests and simply replace the ignition system; hey, it's not their money! I towed her back home and replaced the ignition module; still no change. After running a plethora of tests, I replaced the PCM and she's run perfectly ever since.

Good luck.

HelpMyCadillacPlz
11-14-06, 02:20 PM
Ok so today i checked the codes, but didn't come up with any. "No Codes" repeated over and over again until 'PCM?' popped up. Does that rule anything out, or bring any new possibilities to the table? Could it still be the CPS, or would that problem have been listed in the codes? Could i need a new PCM? I'm taking her into a shop tomorrow, and i need to decide on what i'm gonna tell the mechanics, because most likely they're not going to be able to recreate the problem. If i suggest CPS, do you think they would investigate before replacing, or just go ahead on my word? Seriously, i need some advice. This is the biggest, and most irritating car problem i've ever had, and i've had some terrible cars.

dkozloski
11-14-06, 02:28 PM
FWIW, A good place to start with solid state electronics is to unplug and replug the PCM and all related engine stuff several times. This will verify that it isn't a bad connector or some corrosion. This costs nothing but time and may save you a bundle. I've seen PCM's replaced and the trouble goes away. The original PCM is put back to verify the diagnosis and the trouble is still cleared.

Ranger
11-14-06, 05:25 PM
"PDM?" is simply asking if you want to enter the PCM mode. CKPs don't always set a DTC from what I have heard, though mine did. I am sure that if they cannot duplicate it and you ok throwing a set of CKP sensors at it they will do so. It's your money.

dp102288
11-15-06, 08:57 AM
I would be surprised if the PCM fixed your problem, but if it did, congrats!

codewize
11-15-06, 05:07 PM
A quick thought is, IMHO the CPS' Will cost you $70 and an hr of your time. They're destine to fail anyway so if you eliminate that problem now you're gaining 2 fold.

One is you fixed the current problem AND you've eliminated the chance of breaking down do to the failed CPS.

If the CPS's don't fix the current problem then you bought a $70 insurance policy for the future.

MUGSANDLUKE
11-15-06, 08:40 PM
I'm not sure if I have a similar problem, but anyone's input would be helpful. Twice in the last few weeks, the engine just shut off while I was making a turn on an entrance ramp. Very Strange, and dangerous as well! Had to shiftinto neutral while rolling and start it again. Of course the power steering and brakes shut down at the same time. Not a pleasant experience and quite a surprise when it happens. Is it possible that the cause is the CPS's that are being discussed here or is it possibly another cause that I'm missing? If anyone has any ideas I'll listen. Thanks

Ranger
11-15-06, 10:16 PM
Sounds suspiciosly like CKP sensors Mugs. Any DTCs? What year is it? GM had a bad supplier 2000 til early '03.

codewize
11-15-06, 11:39 PM
Ranger, whats a CKP?

Ranger
11-16-06, 01:38 AM
Crankshaft Position sensor. We (including myself) have been calling them CPS, but someone pointed out that the FSM actually calls them CKP sensors. I remembered that after it was pointed out. Figured I should use the proper acronym.

MUGSANDLUKE
11-16-06, 06:47 PM
Hi again - I have a 2000 Deville DHS. The problem is not constant and hasn't happened again for quite some time but it's always in the back of my mind that it could. It makes me a little uneasy and that's the real problem. I was just wondereing what, if anything, could be checked and/or replaced to eliminate the chance of re-occurance. Any ideas or opinions??????

Ranger
11-16-06, 07:34 PM
I'd replace the CKP sensors. If they have not been replaced yet, they eventualy will. May as well do it now.

codewize
11-16-06, 10:39 PM
Ummm OK Thanks.


Crankshaft Position sensor. We (including myself) have been calling them CPS, but someone pointed out that the FSM actually calls them CKP sensors. I remembered that after it was pointed out. Figured I should use the proper acronym.

pimpincaddystyle
11-22-06, 11:15 PM
hey this has happened to mee to...went on for a year and a half before i replaced the fuel pump all better now

codewize
11-23-06, 09:29 PM
Crankshaft Position Sensor = CKP Right? :hmm: :helpless:

Ranger
11-23-06, 09:49 PM
Yes.

codewize
11-25-06, 10:28 AM
Oh you didn't have to confirm that Ranger. LOL sorry I was just making fun of the acronym. I was re-reading the thread and had to laugh so I figured I'd post my thoughts. You have to love America.

Ranger
11-25-06, 10:34 AM
Roger that. I agree, CPS makes so much more sense.

infin1ty
11-27-06, 08:58 PM
As a conclusion, please list the resolution to your problem, once it is identified.

Gearheaad43
12-04-06, 12:04 PM
Please let me jump in here with a possible solution to identifing when a PCM might be going south... Hasving owned 10 GM cars in the past , I've had to change a few ECM/PCM's... This sits true for OBD1 ECM's, it should work for the OBD2 PCM's..

Alot of times when the Brain goes out, it can not diagnose itself. Therefore a code will not register. But the problem is almost ALWAYS related to a loose connection somewhere inside the ECM/PCM box.

This can be verified by what's called the "SLAP" test.

With the car running.. Expose the ECM/PCM and with the palm of your hand , give it a good SLAP. 3 or 4 times about a few seconds apart.
If you notice a change in RPM, or the engine stalls and quits ... It's a good sign the ECM/PCM is headed south.

codewize
12-04-06, 02:32 PM
This is only the second time I've heard of this archaic method of automotive diagnostics. I also firmly believe it pertains to late 80's early 90's vehicles.

However I did tell my mechanic that he was nuts for slapping a computer. Especially when the new $350 PCM didn't fix the problem that the car was in the shop for. Funny thing though, it was an idling problem.

I don't think hitting a computer is a good idea at any time. If it's not the problem you may make it the problem by doing so.

Gearheaad43
12-04-06, 03:07 PM
Slappng it firmly but not with alot of brute force will not harm a good unit. GM is notorous for using suppliers who utilize cheap soldering. The solder welds over time will corrode / loosen causing intermittant problems. I've seen warning lights on IPC's come on by themselves because of poor soldering to the circuit boards. You can only imagine what's going to happen with a loose solder connection inside an ECM/PCM. :rant2: :rant2: :rant2: :rant2:

codewize
12-04-06, 03:18 PM
I guess you're right and I have heard many stories about inferior soldering. I would think there's a better way though. Like I said. A mechanic of mine, or should I say an Ex-Mechanic of mine replaced the PCM in my 89 STS swearing that he performed this 'slap' test and was sure that the unit was the cause of the erratic idle.

$350 later I still have the problem which he then told me that it was being caused by a worn throttle body, also not the case. Everyone was calling my car a POS and a lemon because of one small problem that cost me thousands of dollars in repairs because of one person who didn't have a clue.

I guess my point is I'm comparing the quality of person who uses this test to the quality and reliability of the test itself.

dp102288
12-05-06, 09:11 AM
^^ Drive it to Ranger...he can fix your car! :D

So slapping the box wouldn't mess up a good one. I don't slap anything with the word "control" or "computer" in it.

codewize
12-05-06, 08:59 PM
:bigD: :coffee: :thumbsup:



So slapping the box wouldn't mess up a good one. I don't slap anything with the word "control" or "computer" in it.

Gearheaad43
12-05-06, 09:30 PM
I don't slap anything with the word "control" or "computer" in it.

You Chicken!!!:stirpot: :stirpot: :stirpot: :duck:

dp102288
12-06-06, 09:31 AM
Hey, my computer is the way I keep my sad life sane, and the controlling girl is the only one that is sane! :p

kcclark
12-10-06, 09:51 PM
HelpMyCadillacPlz,

Any updates?

Rag64top
12-16-06, 03:30 PM
About slapping computers..
I have been in the computer field since 1975, and over the years, I cannot count the number of times that I brought out an intermittent problem by banging, slapping, tapping, or whatever else it took to find the problem.
Now, I realize that this should not be substituted for actual troubleshooting procedure to find the problem, but it sure helps when all else has failed.
I used to work on mainframe systems that had a huge wired backplane assembly, probably about 3'X2' with thousands of interconnecting wires, and a couple of hundred single height computer modules inserted in front.
When all else failed to find the intermittent, I would take a credit card, and "fan" the pins on the backplane, and this would bring out the intermittent connections. I also used the technique of using a screwdriver handle to tap on indivdual modules, (when they are up and running) to find intermittent boards or pin connections.
I had a 89 chevy van that would die all the time, the motor would just shut off. When I found that the comuter box was under the drivers seat, I started to KICK the computer trying to see if it was cutting out. If I went over bumps, the car would sometimes die. Kicking the computer caused the truck to shut off, exactly as it had been doing to a few weeks. I could even get it to shut off, and then kick it again, and it would come right back on!
I went to the junkyard, and got a new computer for $50, problem fixed!
Bottom line, bitch slapping a computer module won't generally harm it, of course you wouldn't want to take a hammer to the thing, but I would suggest tapping any suspected component with the plastic handle of a screwdriver, it has allowed me to isolate MANY problems over the years.
And you should see the customers face, when you start banging on their 2 million dollar mainframe! I would usually find a way to get rid of them before I do these types of things. But IT WORKS. Most electronic problems are generally just a bad connection somewhere, whether its in a harness or a pin connection, or withing a module itself. Lots of poor solder conection can be found with the "tapping technique"
WARNING, do not attempt to use this method on a hard drive, NO tapping on hard drives!


Peace
Rags

dkozloski
12-16-06, 05:25 PM
I was plagued with a bunch of IBM monitors with intermittant brightness problems. I would take off the case, turn out all the lights in the shop, I'd even cover the crack at the bottom of the door, turn on the monitor and lightly tap around the high voltage supply with a wooden stick. The cracks in the circuit board and bad solder joints would show up as the tiniest of arcs. I'd mark the problem areas with a felt tip pen for repair. The culprit was people pounding on keyboards 24 hrs a day in front of them.
The big problem in mainframe backplane came when the bearings in the cooling fans would fail and scatter tiny ball bearings all through the connectors. I never found a quick way to deal with that.

dp102288
12-16-06, 09:04 PM
Slapping mainframes...that would probably scare the hell out of me and my wallet!

AlBundy
12-16-06, 09:21 PM
:histeric: Well you have your choices a tap, slap, hit/punch or kick. You chose.

Rag64top
12-16-06, 09:24 PM
My favorite one was boxing the ears on a blank screen VT52, (that was an old DEC monitor).
The pins on the pwer supply board would oxidize, and you could bring it back to life by slapping both sides of the monitor at once, box its ears....LOL
Voila, screen was fine now for another year or so..
Peace
Rags

dp102288
12-17-06, 09:24 AM
^^ Imagine if that was in the instruction book...

"At least once a year box the ears on your monitor to ensure proper operation."

:D

Submariner409
12-17-06, 12:18 PM
:alchi: Yep, replaced both CKP in my '02 STS at 32,000 miles. Caught the problem under warranty and my dealer said better to replace both. Nary a problem since. BTW, most of this thread sounds just like the "slap & tap" diagnostic procedures used by the ET's (Electronic Technicians) on any number of systems in a nuclear ballistic missile submarine:tisk: . Another was the "Greenwater Float Test" and a third was "Easter Egging", which required replacement of ever more parts until the thing worked. It's simple with tax dollars........and tracking down an intermittent open trace on a modern circuit board is damn near impossible without some pretty sophisticated equipment Have a Merry and a Happy.....

FrankT
12-17-06, 02:40 PM
About slapping computers..
I have been in the computer field since 1975, and over the years, I cannot count the number of times that I brought out an intermittent problem by banging, slapping, tapping, or whatever else it took to find the problem.
Now, I realize that this should not be substituted for actual troubleshooting procedure to find the problem, but it sure helps when all else has failed.
I also used the technique of using a screwdriver handle to tap on indivdual modules, (when they are up and running) to find intermittent boards or pin connections.

Bottom line, bitch slapping a computer module won't generally harm it, of course you wouldn't want to take a hammer to the thing, but I would suggest tapping any suspected component with the plastic handle of a screwdriver, it has allowed me to isolate MANY problems over the years.

Most electronic problems are generally just a bad connection somewhere, whether its in a harness or a pin connection, or withing a module itself. Lots of poor solder conection can be found with the "tapping technique"

Peace
Rags

Rags,
Well said, I use the exact same techniques. I wrenched at a Lincoln/Mercury dealership for 20 years. I was one of drivability techs, my favorite tool used to find intermittent problems was the handle on my pocket screwdriver. Using the handle to give a little tap on the suspect component would bring out the fault quit often. The Ford shop manual called it the tap / wiggle test. I can't tell you how many fuel pump relays, power relays, TP sensors, TFI Modules, EGR position sensors I found just by lightly tapping on them.

I wrenched for over 25 years and I still wrench some on the side. I am glad that I don’t have to wrench for a living now. I still deal cars, not with Fords /Lincolns or Mercury and I don’t need to wrench on them.

Frank

billytheshoe
12-30-06, 03:29 PM
A historgraph will tell.