I have a 2005 Chevy Equinox with 73K miles. When I first start it up morning the car runs rough for about a minute or two and then smooths out. I took it to a mechanic who said there was oil on one of the plugs and to get rid of the car. I tried another mechanic on Craigslist and he replaced the upper plenum gaskets. It ran better for about a day or two and now the problem has resurfaced. I am hoping someone has an idea what the problem is and that it’s not too expensive to fix. I would love to get a couple more years out of this car.
Thanks for all responses.
Fairfax
This is just a guess from what you have described. The mechanic that replaced the plenum gasket caused the computer to reset and this is why the car ran different for a couple days. As the ECU learned the parameters again it went back to its old run state.
If it were me, I would try to get the upper intake system cleaned including the air idle control solenoid. It could be having a hard time getting enough air into the system to run properly until the entire engine goes into closed loop where it monitors the oxygen sensors. You can do this at home with Seafoam and a piece of vacuum line but most people feel more confident getting a shop to do it.
Thanks for the advice. I will give it a try.