5.0 and 5.7 Discussion, Engine ping/knock/miss at all RPM ranges. in Cadillac Engine Technical Discussion; 88 Cadillac Brougham. The engine runs perfect when you first start up the car; once you hit the gas and ...
88 Cadillac Brougham. The engine runs perfect when you first start up the car; once you hit the gas and kick it down, and it gets hot, it begins to shake. Usually when you come to idle it idles real rough. The longer and hotter it gets, the shakier it seems to get.
It'll set codes 21/22/23/42 all at once at WOT. It also has an intermittent engine light setting that I haven't pulled yet.
*Spark plugs(AC delco Rapidfires), wires, distributor cap within the last 9 months. All the plugs look old, one had let some oil into the cylinder.
*Carb rebuilt, TPS/MCS replaced. Idle Load compensator is broke and adjusted so the engine maintains around 900RPM. Everything was timed to default.
*Emissions system rebuilt; new hoses everywhere. Everything but the EFE valve is working fine.
*Oil is fine, although the engine has a few oil leaks.
*No exhaust leaks, replaced the catalytic converter 2 days ago. Gives a nice deep throaty sound.
*One loose belt, don't know if that'd cause it :/.
*New air filter, AIR filter, PCV Filter. Charcoal canister filter and lines could use some work but they're functional.
*New battery; got one of those gel ones.
*Cold air intake is working fine; just put it in a few weeks ago.
I assume this is a 307?
So it runs fine with the choke and therefore running on a rich mix (choke flap almost closed), then craters when the flap opens and the mix goes too lean. Sounds like there is a vacuum leak or something that is causing a lean mix, which can cause the symptoms you are describing.
Did you set the timing with the A&B terminals on the diagnostic linked jumpered together? The timing could be way overadvanced.
Did you check the idle mix by using a dwell meter on the green connector in front of the carb?
Did you check the voltage at the TPS sensor?
Have you checked the EGR valve and the passages that feed it from below the carb?
There's info on how to do this within this forum, so I won't get into that, but these are all things that have to set to spec or else it just won't run right.
I would also look at the float level as well as the mix solenoid/lean idle settings. Don't know who rebuilt the carb, but a good rebuild includes resetting all the internals back to factory specs, lots of mechanics stick a kit on it and call it good.
Guy who did the carb has done hundreds, he set everything to factory then tweaked it up just a tinge to get it to work right since factory it usually runs like shit, epoxy'd the lead stoppers, and installed a new gasket kit. He felt the carb on the car was crap and whoever was in it before ****ed it up good. He also timed it to factory spec and when I got the car it had twice the power and acceleration and didn't miss at all. I think after the ECM adjusted some is when it began to lean out and miss.
I'm having a feeling it's in the ignition. The o2 sensor was just replaced and it didn't set codes for rich mix (45 which is intermittent) until it was replaced. The old o2 sensor corroded as hell. The car sat for 5 years; the ignition wiring/advance is probably fubar and needs work and that's the one spot I haven't checked. It'll NEVER set a code at idle when in park, but once you start accelerating it'll start doing it so it's an issue that gets worse as RPM/load increases.
All emissions systems are working perfectly including PCV.
I am an old member who has lost my history and crap on this site. Anyhow, briefly read about your problem and have some thoughts. As everyone thinks- this could be a timing issue- which can be tested by loosening your distributor retention bolt and rotating it slightly clockwise or counterclockwise to determine if ignition timing is the culprit. As we all know Ecm cars are supposed to be set on 0 and the computer advances and retards spark. During a cold start, the ECM retards the spark and gradually advances. Back to Basics- If the Distrib is off- this could cause the symptoms you describe. Now, more likely an excessive carbon buildup on the valves which becomes superheated after the engine gets warm and causes pre-ignition, or the rebuilt carb ran soo lean an exhaust valve burnt a little causing a leak like a chip on the edge of it also causing cylinder pre-ignition. If the knock/ miss happened suddenly after the carb was done you may have an easy fix- timing. Most likely- It sounds like you went out and ran your car real hard and either burnt or bent a valve. This can be diagnosed with a simple compression check. Good Lock!
This car sat in a guys garage for 5 years before I got it. So the gaskets have been going out 1 by 1 and all the rubber has been degrading. It also had rats in the engine compartment and a bunch of wires and emissions lines were chewed through which is why I suspect the timing.
Basically, when I first rebuilt the emissions system and changed spark plug wires in Febuary, it ran perfect; no missing at all. As time went on, it began missing more and more. I replaced more stuff, missed less. Now, it's missing again. Carb got rebuilt, didn't miss at all and again the missing slowly came back. I've seafoamed the oil and fuel a few times which has shown a major improvement in power.
I'm not sure as to what's going on but it seems like I'm fixing shit and it breaks again. The Wiring is something I'm going to look at replacing soon. For the time being, the car runs and runs well and I'm just going to enjoy driving it for another week or so before I crawl ontop of the engine commando style and inspect the wiring on the distributor.
Right now I'm saving for another car; a nice 4 banger, and I'm going to figure out whether or not I want to trebuche' this one into the Atlantic or finish the job I started.
2 months ago when I changed out the starter we accidentally unplugged the distributor/ignition. She cranked even without a hitch.
Oil in the cylinder from oil leaking onto a spark plug can cause missing? That's probably half the problem right there; I've got 2 leaky head gaskets, one of which has worked it's way through the spark plug threads. I'll definitely have to look into that as well as a compression check.
Reading plugs always gives great info. You can tell a lot from them. Get a magnifying glass or a low power microscope and examine it closely.
Oil can if it is that bad. Probably see some smoking too if it is that bad. JC Whitney has some plugs that are supposed to fire in oil, not sure if they really will, but might be worth one if a bad cyl. I have used those spark plug thingies that pull the plug back to keep it out of the oil with satisfactory results. Still that engine needed help (455 Pontiac with a zillion hours idle time) and needed head work done. Got me by. To know how much oil? 22 quarts to go 800 miles. I stopped every 50 miles to "top off".... And hardly any smoke.... And the engine only had 54K miles on it! It was a hearse engine...... But the power in a 455 Poncho!
This weekend I'm going to be pulling the valve covers and replacing the gaskets, washing the engine, inspecting and torquing the lifters to the proper spec torque, and potentially doing a compression test, then filling the tank with 10 gallons of 87 and a can of sea foam as well as an oil change more than likely. We'll see then what's wrong with the caddy.
You know, it sounds like the carb is not delivering fuel to one side of the engine. Check the plugs, look for irregularities in the plug color from cyls 1, 7, 4, and 6 and then 2, 3, 5 and 8. IIRC those are the joined cyls in the intake manifold (aka, 180 degree intake or dual plane intake). So if one side of the carb was blocked for fuel, either from a blocked air bleed or something.
Carbs MUST be kept clean!! Blast down all the air tubes and bleeds, they are cruicial to proper carbie operation. You would be amazed at the change of A/F ratio when an air bleed is even 30% blocked.
A friend of mine had an E4ME running badly and it was the M/C Solenoid STUCK down, so it was forced lean all the time.
When I pulled plugs a few weeks ago all of them were grayed out, I think maybe one had a little orange on it, but overall none of them were that bad. The two from the oil fouled cylinders had some carbon buildup on them, and one was gapped (although that may have been from the sludge AROUND the plug as I pulled it...in any case, yah..bad). Pretty even overall from what I saw, and those were in for just under a year.
I've got cork valve cover gaskets and engine degreaser, a factory service manual, and a clean garage to work in after we get my buddies truck to go from "streaks" the truck to hopefully "dribbles" the truck, down from puddles. It's a GMC K1500 Pickup with a 305, and he complains "I've got to put 2 quarts of oil in it a day!".
Water pump, pump gaskets, thermostat, oil pan, oil pan gaskets, oil pump, tried to convince him to do the timing chain and cover but he doesn't want to; the engine has to have about 160k miles on it. When that starts leaking I will tell him "I told you so" as I always do.
The Alternator died on Wendsday night; a bearing went, causing it to make a lot of noise and heat, melting and ultimately frying the bearings. The Gel racing battery I had in there did it's job; got home on Thursday and didn't even know until Friday morning when the engine wouldn't turn that the alternator was dead. Went out and replaced it with a buddy. Turns out the new alternator, which I knew was bad the moment I opened the box, did the job to get the car home from the parking lot but fried in the same exact way. The drive home was very very nice; I couldn't believe the car wasn't shaking anywhere nearly as bad as it was before and she started up without a hitch in the morning unlike the day prior. I was wondering if it wasn't shaking or if it was psychosomatic that I didn't feel anything.
Yesterday we pulled the bad alternator, got a replacement, then completely pulled the emissions system and did the valve cover gaskets. Take it as a lesson, to get at the head cover gaskets you need to remove the AC pump, AIR pump, the Alternator, EGR, all the vacuum lines and half the emissions equipment, a few brackets, and pull the heater box partway off and then you can get at the head cover gaskets. Might as well change out the timing chain while you're at it and partway pull the engine and do the oil pan gasket as well.
AS a note, if you find any 1970's varnish remover in your garage, it works great for cleaning the valve cover . The only problem is it gets more potent over time and damn near burned a hole in my hand .
In any case, I got everything back together today and it worked fine, save for the new cork valve cover gaskets leaking like a faucet. I have streaks of oil running down both sides; the bolts are properly torqued so I think my buddy screwed up on the installation.
He knows more about gaskets than I do so I'm going to get him to take a look at it tomorrow and see what he did wrong since he was the one who put them on in the first place. If we've got to do it over again I'm getting thicker gaskets and RTVing the fsck out of them or something because I never want to have to do this job again for as long as I have this engine in this car.
I might also replace the AIR pump and a few other odds n' ends in the engine compartment such as the positive battery lead (already replaced the negative with a longer one).