Hi all... I tried searching for my answer a few different ways but came up with similar but not same results so here is the problem I am having with my Buick.
It all started just out of the blue by the engine loping a bit when I would slow down or come to a stop sign and sit in gear at idle. Just a slight lope, roughly 500 rpms or so.
The next week it got worse. Engine light came on. 1000-1500 rmp lope and the voltage would drop and then increase as the rpms climbed back up. Back and forth it would lope somtimes constantly, sometimes constantly and then the engine would die, sometimes it would lope and then level out.... but always it was loping either in gear at idle or in park or neutral.
Went to O'Reilley's auto and told them what was going on and the guy put a tester on my battery. The battery was fine but he said my alternator was shot. The alternator was drawing 30 amps when it should have been drawing 140. Said thats the problem, replace that and you will be good to go. So I spent $120 on a new alternator. Woah! Everything was a lot stronger now... Popped right off when I turned the key now, the fan had a bit more uhhh.. blow? to it... and even the lights seemed a bit brighter (probably my imagination) but... it didn't fix the problem. Engine still loped, but now.. only when I put it in park or neutral. grrr.. ok. Did some research on the net and saw a lot of different problems that it could be.
So far I have done these things:
-- Alternator - replaced
-- Battery terminals - wires cleaned and posts replaced
-- Ran my gas down to empty and filled with premium and poured some injector cleaner in there
-- Checked vaccuum hoses for leaks
-- PVC valve - replaced
-- Mass flow air sensor was gummed up - cleaned it
-- Idle Air Control Motor - replaced
Other things that I looked at as far as possibilities:
No fluid leaks or low fluids, I mean as far as coolant or oil or tran fluid.
Not sure what is next. ??? It is starting to get cold out here and I'm almost at the point where I am going to have to take it in if i don't figure this out soon. I did have it tested on a machine for the codes.. First one was oxygen sensor but I was told that it was a false reading due to the alternator failing. Next one was was mass flow air sensor but I cleaned that and that code went away.
Right now it is idling / loping erratically again, off and on, at stops in gear, in park, neutral. Even a drop in accelration will drop my rpms and my voltage drops. Wants to die but catches itself and then lopes again.... argh... help!
This is a picture of my engine for a sort of visual