1992 Bonneville issues

So I bought a 1992 Pontiac Bonneville SE for $800. Straight body, good interior but it runs like crap. Here is my conundrum; It runs great UNTIL the thermostat opens... then it stalls on idle. I have replaced the PCV valve, the Fuel Pressure Rugulator and cleaned the Idle Air Control valve and MAF. It still runs great when cold, then stalls at operating temps. It seems to be a vacuum leak at the manifold, so I have ordered and will replace EVERY seal, O-ring and gasket throughout the ENTIRE fuel/air system. Just wondering if any ATSers have dealt with this issue on early 90s GM cars... any input would be helpful and appreciated

(Great troubleshooting starts with great research... )

You may want to try replacing the control module under the coil pack. Sometime when they get hot they get weaker.

Does it just stall at idle but is ok off idle? Or does it die once warmed up then not start till cool?

Non-GM dude here. But I had a 1992 Lincoln Town car. If you look under the hood, going in and about the throttle-body, you will see numerous vacuum hoses. If it runs like hell, I suggest going through all of those little hoses and replacing them. One little vacuum leak can really screw up performance and reliability.

Never hurts to do the oil, to check for water contamination, look under the valve covers to see how well the previous owners maintained it. If it's full of clingy black gunk, then they didn't service it regularly, and good luck tracking down all of the damage.

Clean air filters, plugs, cables, and any corrosion that you may encounter. Also, buy some di-electric grease and go through all of those electrical fittings and relays. Connectivity can be a big deal depending on the area the vehicle came from.

Good luck.. I remember the 92 Bonnies. They had quite a lot of bells and whistles, and were pretty fun to drive.

Boba

originally posted by: caterpillage
Does it just stall at idle but is ok off idle? Or does it die once warmed up then not start till cool?

It runs GREAT off idle... plenty of power as the GM 3800 is capable of... on idle at operating temps it sputters and dies

originally posted by: buster2010
You may want to try replacing the control module under the coil pack. Sometime when they get hot they get weaker.

Already looked... not a common offender, but did OHMS check each coil pack and all are within specs

originally posted by: Bobaganoosh
Non-GM dude here. But I had a 1992 Lincoln Town car. If you look under the hood, going in and about the throttle-body, you will see numerous vacuum hoses. If it runs like hell, I suggest going through all of those little hoses and replacing them. One little vacuum leak can really screw up performance and reliability.

Never hurts to do the oil, to check for water contamination, look under the valve covers to see how well the previous owners maintained it. If it's full of clingy black gunk, then they didn't service it regularly, and good luck tracking down all of the damage.

Clean air filters, plugs, cables, and any corrosion that you may encounter. Also, buy some di-electric grease and go through all of those electrical fittings and relays. Connectivity can be a big deal depending on the area the vehicle came from.

Good luck.. I remember the 92 Bonnies. They had quite a lot of bells and whistles, and were pretty fun to drive.

Boba

Guessing it came down from Alaska... as it does have a block warmer The ride is amazing for a 22 year old car and it handles like a dream.... until it sputters and stalls...

originally posted by: Bobaganoosh
Non-GM dude here. But I had a 1992 Lincoln Town car. If you look under the hood, going in and about the throttle-body, you will see numerous vacuum hoses. If it runs like hell, I suggest going through all of those little hoses and replacing them. One little vacuum leak can really screw up performance and reliability.

Never hurts to do the oil, to check for water contamination, look under the valve covers to see how well the previous owners maintained it. If it's full of clingy black gunk, then they didn't service it regularly, and good luck tracking down all of the damage.

Clean air filters, plugs, cables, and any corrosion that you may encounter. Also, buy some di-electric grease and go through all of those electrical fittings and relays. Connectivity can be a big deal depending on the area the vehicle came from.

Good luck.. I remember the 92 Bonnies. They had quite a lot of bells and whistles, and were pretty fun to drive.

Boba

And, yes, doing a full tear-down this week. EVERY seal, gasket, o-ring and electrical connector on this motor will be inspected and replaced as necessary. I hate that this car is parked... fun to drive when she runs

originally posted by: madmac5150

originally posted by: caterpillage
Does it just stall at idle but is ok off idle? Or does it die once warmed up then not start till cool?

It runs GREAT off idle... plenty of power as the GM 3800 is capable of... on idle at operating temps it sputters and dies

Allright then I'm thinking an iac problem, possibly minimum air. Clean throttle body with carb cleaner, tooth brush works good,

A scan tool would be great here, iac counts should be around 20 if everything is sweet, if it's closing to zero you have a vacuum leak, if it going high like 60 you have a minimum air issue.

Could also be an egr problem, these motors have electronic ergs and if the egr opens at all at idle it will kill the motor yet run fine off idle. Egr could be a serious suspect here.

A easy way to detect a vacuum leak is with a little propane bottle. Just start the engine, crack open the propane a little, then run it over the hoses. If/when the engine revs up you have found the leaking hose. I know it sounds sketchy, but it works.

originally posted by: caterpillage

originally posted by: madmac5150

originally posted by: caterpillage
Does it just stall at idle but is ok off idle? Or does it die once warmed up then not start till cool?

It runs GREAT off idle... plenty of power as the GM 3800 is capable of... on idle at operating temps it sputters and dies

Allright then I'm thinking an iac problem, possibly minimum air. Clean throttle body with carb cleaner, tooth brush works good,

A scan tool would be great here, iac counts should be around 20 if everything is sweet, if it's closing to zero you have a vacuum leak, if it going high like 60 you have a minimum air issue.

Could also be an egr problem, these motors have electronic ergs and if the egr opens at all at idle it will kill the motor yet run fine off idle. Egr could be a serious suspect here.

True story: I thought the EGR valve could be a problem... the EGR opens on operating temps, and it is a likely cause... SO... I bought a replacement EGR just to find out that the 1992 GM 3800 is the ONLY damned Pontiac that does NOT have an EGR valve.....

a reply to: madmac5150I assume its got the 3.8 V6, Im a GM w-body guy and those are one frame size down from your bonnie. Have you checked your spark plugs and wires? You can test the resistance of the wires and I`d like to remember the magic number for 7mm wires is 15ohms. I could be mistaken. You might want to check out the forums at www.forums.h-body.org.... They specialize in the 3.8 90 degree family and can point you towards all sorts of tips, parts, modification etc. If you do not get much help there you can PM me and I`ll link you in to the w-body site and I know those guys can help, even if its to drop in the supercharged version of that engine.

Is your ck engine light on? If so a scan tool would be The first place to start. Also The intake manifolds on gm v-6 motors with plastic manifolds are notorious for corroding on high mileage vehicles. Normally with this you will notice coolant in The engine oil. Even with No ck engine light The scan tool will help. Possibly a coolant temp sensor reading out of whack. Should be ambient temp When first started after sitting overnight, and should rise to 220 When The fan comes on. The resistance on resistor spark plug wires Is 1000 ohms per foot, a 2 foot wire should be 2000 ohms and so forth. Also some 3.8 motors have a housing that The pcv valve goes into, you twist The plastic housing to remove it, there should be a large o-ring where The valve goes into The intake. The o-ring gets lost lots of times and causes a vacuum leak. Lots of other possible causes, But scan tool data should start to point ya in The right sirection

a reply to: rustydog


No check engine light... pulled the intake manifold gaskets and they were BLOWN TO HELL... obvious signs of leaks. Got them installed, now waiting on the 24 hour cure time for the RTV...

a reply to: madmac5150

There ya go, does it have The plastic upper intake?? I've seen many of these plastic intakes corrode badly around The coolant passages. If No corrosion replacing The gaskets should Do The trick. If ya still have problems just let me know, always happy to help When I can!!

COMUTER RELEARN PROCEDURES (ALL MODELS)

When the battery is disconnected computer data is lost; default data is used until new data from each key start is stored. After the computer restores its memory drivability is restored.
Symptoms are: Rough Idle, hesitation or stumbe, rich or lean running, bad fuel mileage.

To accellerate the computer relearn process vehicle should be road tested as follows:
1. Start car and get to normal operating temperature (cooling fans running).
2. Accelerate slowly to 20-50% throttle. Cruise at light to medium throttle position, decelerate to a stop.
3. Repeat 3-4 times.
-------------------------------------

wouldnt hurt

originally posted by: madmac5150

the 1992 GM 3800 is the ONLY damned Pontiac that does NOT have an EGR valve.....

i would love to see some close up pics of your engine.....
youre positive about that?

does yours look like this?