Hi everyone! I have a 2007 Chevy Impala with 111k miles, and it's starting to act up. It was shaking a bit at idle, so I replaced the spark plugs and wires, and it ran a lot better for a while. But, after I tried to use to AC for the first time, it has been randomly jerking (almost feels like a misfire) at idle (this even causes the headlights to dim.) It's pretty infrequent, but concerning.
This occurs whether the AC is on or off. But, when the AC is on, it feels like the engine is fighting against something on the serpentine belt. The AC is not as cold as it used to be, and it feels like the airflow varies far more than it used to.
Because of this, I've just been driving with the AC off. This has stopped the lack of power I was feeling, but hasn't completely stopped the strange jerking at idle (and one time at 45mph.) The transmission also feels a bit sloppy on this car, so it's a real gem haha.
Do you think a bad compressor could be causing all of this (I hear a faint whining noise from the alternator/compressor area when the engine is idling), or did I do something stupid? The engine runs great otherwise. Thanks!
(Alternator outputs 13.9 volts at idle, long term fuel trim is -3.1.) Thanks again!
Well you obviously have problems with the car even with the AC off. Turning the AC on merely accentuates the problem. I would start by testing the battery and alternator. Maybe one of those is weak. But if not, that since the transmission's going to, I would say you have probably three different problems, a running problem, a transmission problem, and a weak AC that's straining the engine. Those are pretty crappy cars and I don't think I'd put much money into that thing. You'll never get it back in the long run
