rustyroger

I fired up my '87 Olds today after not using it for a few months.

It started just fine (with the aid of jumper cables) and I left it idling while I washed it. It ran well, the fan cut in at normal temperature and all seemed fine.
Then it started stumbling and then stalled. It fired up again no problem but would not idle.
I cleaned the MAF sensor and thought I had fixed it but after a few minutes it stumbled and died again.
I took it for a drive, under any kind of load the engine is its normal silky smooth self, but it would stall if I came to a stop.

When I first got the car it ran like a bag of nails, new plugs and wires completely cured the problem. The plugs and wires are around 9k miles/2 years old.

It is a multi point injection 3 coil engine.

Any help or suggestions gratefully recieved.

Roger.

Aceshigh

3.8L's are notorious for bad intake gaskets leaking coolant into the engine.

If you find this to be the issue, I'll bet money it is.......
You should look for the best option in gasket to resolve the problem permanently.
Don't use the cheapest option......again.

Allan R

Dunno about that. I agree the intakes suck. Mine crapped out too, but didn't cause the engine to quit or run rough. Lucky I guess. But the stumbling problem sounds more like what happened to my 3.8
1. Check all your vacuum lines for cracking/disconnect or leaks
2. Test your IAC to see if it's working (dry steer the car to see if rpms kick up - that would indicate the IAC motor is working)
3. My problem was with the coolant sensor - the connector had broken wires. Once I replaced that pigtail it was fine.

Just to be on the safe side about the coolant issue, check your oil to see if it's turning a light chocolate brown or whitish color. If it is you have a serious gasket problem. If it's fine, take off the IAC, clean the pintle and then spray a shop rag and clean the pintle seat in the throttle body. Put it back together and test.

BTW - you reset the IAC after cleaning by doing this:
Turn all accessories and lights off
Turn key to 'run' but don't start - for 20 seconds
Turn key to 'off' and wait 10 seconds. Then start. If it's an IAC problem this should resolve it.

rustyroger

Thanks Aces & Allan;

I always check the fluids before startup if the car has sat for a while, It never loses coolant, maybe burns a pint of oil over 5k miles - I dont top it up, it gets an oil change then.
All was fine this time too.

I will check out the IAC this weekend and post what I find.

Thanks once more;

Roger.

jerseyjoe

IAC and mass air flow. The mass air flow sensors were noted for going bad back then. We use to replace them as well as power antenna's and door window guides constantly.

Allan R

IAC's are around 35-40 bucks. MAF's can be cleaned but if you need a new one it's also not pricey at around 60 bucks. For less than 100 you could probably be back in business. Not likely that both are bad; just one. I'd start with the IAC

BTW, curious about something. This thread is about an 87 Olds but you put the title as 3.8 Buick problem. ???Sup with that???

rustyroger

It will cost me a lot more than the prices quoted for new parts over here.
#1 problem is getting hold of them in the first place, I've learned a lot about repairing parts rather than simply replacing them since I got into the American car hobby.

My Olds has a 3.8 Buick V6, that's why I posted in Non Olds Powered.

Roger.

rustyroger

Got under the hood today, the car started just fine and ran at fast idle until it warmed up, then dropped to 740 rpm (according to my timing light) and ran just fine, like there had never been a problem.

It drove perfectly as well, no stumbling or stalling at all.

Since I had done nothing under the hood I had another look and tried disconnecting the TPS which made the idle speed increase significantly, I did the same with the IAC which made no difference at all.
When I got back in the car I saw the "service engine soon" light was on. I turned off the engine and restarted which made the light go out and stay out. I think that was because I had disconnected the TPS and IAC.

I guess I'll have to see if it happens again, thank you to all who offered help.

Roger.

jerseyjoe

It is possible you got water into something when you were washing it?
Another possibility may have been a chunk of carbon was hanging up the egr valve and finally blew out...Glad it is running normal again.

Allan R

Washing isn't supposed to affect (hah! key word isn't supposed) the engine because GM had gone to weather pack connectors then.

However, X2 on the glad it's running again. Whatever you did before the idle problem? DONT DO IT AGAIN 740 in warm idle sounds just about perfect!

rustyroger

What I did before the problem occurred was not use it. Last winter I took it out at least once every couple of weeks, seems the more I use it the more reliable it is.

Since I fixed the running problems present when I bought it the only trouble I had was a blown muffler (embarrassing, I was at a car show), other than that it has been 100% reliable.

I'll mark this post fixed now, if the trouble recurs I'll open another thread.
Thanks once again to all who offered help and advice.

Roger.