1995 buick park ave - 3800 engine. engine runs very rough at low idle and stalls. Runs ok once it is moving. Already replaced TPS, Low idle control servo and EGR valve
Is this the supercharged engine or the standard 3800?
Are you using or loosing coolant?
It is not loosing coolant
Any trouble codes setting?
I only have an OB2 tester which does not go back to 95.
Is there anyway to manually receive codes with ignition switch or another way?
95 was a strange year. It was a hybrid obd2 type.
You should check for things that would cause poor idle. Vacuum leaks, cracked hoses etc...
I've seen it where the Mass Airflow Sensor is dirty and this will cause a rough idle and stall condition. you could remove the MAF by removing the screws from the throttle body and sliding it out. Clean it using a Qtip and some carb cleaner but be gentle. Don't break the sensor element wire.
Other than that, pull a couple of spark plugs and make sure the gap is right on the plugs. I've seen rough idle caused by the wrong plugs or wrong gaps. Also, make sure the fuel pressure regulator isn't leaking fuel into the vacuum hose.
Hope this helps.
Any other ideas, non of the above is causing the problem
Does it just stall and run rough in gear or does it do it in park and neutral as well?
What rpm does it start to run smoothly?
Does it just run rough and stall as you come to a stop?
What rpm does it start to run smoothly? 1500
Does it just run rough and stall as you come to a stop? All the time
Lower RPM misfiring and rough running should be related to a vacuum leak. or lean conditon.
Since you're sure about the MAF sensor and the plugs, you're left with a leak somewhere. If you can get a scan tool that will talk to that year, you should look at the desired idle as well as actual idle, along with the fuel trim readings.
We've seen a lot of upper manifolds melted on the lower manifold's EGR stove pipe. This can cause all kinds of weird issues.
I'm sorry I don't have any more things to check, but without a scanner, I'd just be guessing. I can only give you advice based on things I've seen or what the manual tells us to check.