Questions and Answers
Grand Am Idles Rough
Q. Dear Sir, I got two situations I'm hoping you can help me with. I've already spent about 2 hours or so checking out related info on FAQ section but still can't find the specific answers to my questions.
I have a 1992 Pontiac Grand Am 3.3 liter V-6, fuel injected 3 speed automatic transmission with A/C, C/C, P/S, ABS, and rack and pinion with 100,000 miles on it. The first thing is that the car has a rough idle when hot or cold and park or drive, only when the car has been driven the whole day will the idle somewhat stabilize.
However I've replaced the following: spark wires/plugs, faulty ignition coil, idle air control valve, PCV valve, O2 sensor, air/fuel filter, and cleaned the throttle body, there are also no codes stored in the computer. I've noticed that when the car has reached operating temperature during driving the rpm needle is closest to the .5 mark then the 1 mark, is that normal? Or is it too low because the needle fluxes a little toward up, almost like it wants to be a little bit higher. Any idea why my car idles rough despite all I've replaced?Also can having bad or worn out engine supports/mounts cause the car to idle rough, that's my next situation? I was told that my flange gasket that connects the exhaust manifold to the exhaust pipe (where the spring are to shift gears) was leaking and that it won't help to just replace the gasket because the engine supports are gone, however they didn't check the engine supports they wanted to charge me extra so now I'm wondering is there an effective way for myself to check if engine supports are in good condition? I have a feeling that they wanted to pull a fast one on me, or maybe they were telling the truth?
Do you have an idea why that gasket goes bad? I know the gasket is bad because every time I put the car in gear and accelerate I hear the noise you hear when you have a slight hole in the exhaust, however I'm not so sure about the engine supports. I really appreciate the time out you have taken to try to answer my questions.Thank you for your help.
JoseA. If you ever suspect that a shop is trying to get over on you, you should leave and go to another shop. They can't screw you if you don't let them.
As for the rough idle, you need to get the E-EGR system checked. That has been a cause of many rough idle problems for that engine. I would recommend a dealer for this.
Bad motor mounts can make you feel a rough idle more than create it. If they are bad or broken they will not dampen the vibrations the rough idle causes. The best way to see if a motor mount is bad is to physically inspect them. That will reveal whether they are good or bad. A visual inspection will not always reveal a cracked or separated mount. If the mounts are bad, it will cause added stress to the exhaust flange and cause the gasket to wear out faster. So in that regard he is correct. However, the main reason that gasket goes bad is age.
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