It could still be the coil packs. When at idle the alternator isnt working at its full potential, so it produces a bit weaker spark. On the Eclipse I put a motor in, it idles really low, so much that the headlights dim. Once moving, they brighten back up since the output voltage is stronger. Maybe something is deteriorating inside the coil packs , but isnt at the point where they are a total loss yet. I have no experience with the idle control valve or motor so I cant really help there

 

So the latest is I replaced the coil packs on my car and the P0300 code has gone away. Before I replaced them, I also had a P0171 code come up, but I erased it and then finally after a while, like a week, it has come up again and now stays on and comes back after erasing it pretty quickly, within say 20 minutes?
So, running lean is the code info-

I read about MAP sensors needing cleaning and also about maybe a bad Oxygen sensor. I was going to replace the fuel filter but my haynes service manual says that on 2001 and later, the filter is part of the fuel pump assembly and is not recommended changing periodically like regular fuel filters every @ 65000 miles.

So, I am asking here as maybe somebody knows in particular on my car a probable solution?
It stills has a very rough idle that goes down very low in the 500rpm and lower range, and then sometimes will surge between 1000 and 2000rpm-

Thanx, Lance

 

Hmm just read about a guy that had same code and the wires to the 02 sensor pre CAT were messed up/chunked up insulation and fixing those wires helped. Going out to look at that now-

 

Ok the wires on mine look quite fine, but ya know, even though I do have a cold air intake, right in the area of the throttle body, it sounds like a little of air hiss to me so while at the gas station, I decided to spray some carb cleaner on the throttle body where it meats the place where it mounts that has a gasket in between. Well, right when I spray there, the rpm's immediatley go up so Im thinking I will replace the gasket that goes there where the throttle body mounts.
Maybe this gasket is messed up or something causing the air to come in there too much causing too much air making the car run lean...
Been up all night so I will see about getting a replacement gasket when I wake up...

 

Throttle body gaskets are cheap and pretty easy to install. If you need a Throttle positioning sensor or MAP sensor, I have one.

If you think you need an O2 sensor, check out eBay. I bought one for $38 brand new as opposed to $102 from the auto parts store

 

Ok thanx will try the throttle body gasket and go from there

 

lol my p0300 misfire code is back. I have a feeling it was the vacuum leak causing the misfire codes and the lean fuel mixture codes all along. Im gonna try to hunt down the throttle body gasket and the idle control valve o ring tomorrow at napa carquest or if dealer is open , them.

It seems that it would have a vacum leak if I spray carb cleaner on the throttle body casing and around that little are and the rpms's go up right away-

Hopefully I will find out tomorrow and hhopefully solve the mystery lol

 

Well solved... Turns out it was a vacuum leak because a part on the throttle body, a wierd little plug that has a shaft with a think spring coil mechanism around it goes in the bottom frond side of the TB.
It was loose and hanging out. Tightening it with a new screw and a lock washer and regular washer so it wont loosen again(original screw was missing)solved the vacuum leak and now it idles very nice and no codes are showing now. yaaaay