Engine Performance problem
1998 Chevy S-10 6 cyl Four Wheel Drive Automatic 171000 miles
Everything I've read about code P0171 talks about how the engine is running lean, but I have this code, and my engine is running rich. I have the pungent exhaust fumes similar to a bad cat (which mine is not, as this was just replaced a year ago.)
The symptoms I have are at idle, in-gear, at operating temp, the truck runs very rough - almost dying. Once I start moving, however, it runs just fine. And as I mentioned above, it has a very pungent -rich- exhaust odor. (First noticed the problem while in rush-hour stop-and-go traffic. When I would stop, it would idle rough with the pungent exhaust, but would driver fine once I accellerated again.)
I've cleaned the MAF and IAT sensors with MAF sensor cleaner, but it didn't do anything. I disconnected the MAF sensor to see how the truck would run, and it runs better with it disconnected.
I should also mention that I had these same symptoms about a month ago, and the code that came up at that time was for the O2 sensor. I replaced it, and that did the trick - until now.
Other places have mentioned testing the vacuum, but how would I go about doing that myself? I've heard reference to spraying starter fluid into the intake to see if it has any affect on the RPMs, but I'm not clear on why. Is that if there is a reaction, then there's no leak? Or vice versa.
My next thought is the MAF sensor is bad, but I don't want to spend all that money until I'm farily sure.
What are your thoughts and/or suggestions?
Tuesday, July 29th, 2008 AT 10:58 PM