High Idle, running super rich... any help appreciated

[Kujo II]

Hey guys, so I'm posting to get some feedback mainly to validate my theory more than anything, so here goes...

'90 N/A 5-speed

Idles High (1200-1400RPM)I checked everything in the world on this one, cleaned aac, adjusted, etc. Does not idle down even with adjustment screw all the way in and aac unplugged.

Misses on driver's side second cylinder when cold

Runs really really rich, can stink you out of the garage in 30 seconds flat. After I drove it on the highway for a while it seemed better, I figure it finally managed to clear the cylinder

No DTC's

Gets about 12 mpg highway

and now for the kicker-

its got gas in the oil.

I'm thinking its got a bad injector in the cylinder it misses on, but if I'm gonna tear the whole thing apart, I figured it's a good time to get them all.

Thoughts? alternate theories?

[chriscordier]

i have exactly the same problem, minus the gas in oil. it smells heavily of exhaust and it gets 12mpg. i have changed all 6 Injectors and they all work fine they were done by a Z shop, so all i can say is thats not our problem. that aside, can anyone please help i am also baffled

[nightops]

did you check the resistance on the coolant sensor on the front of the engine? it could be stuck in warmup mode if it doesnt throw codes. however, bad injectors dont always throw codes- you say they were done by a z shop but if the o rings werent installed correctly it could be leaking fuel from that. you could also have a vacuum leak somewhere and that would cause a high or inconsistent idle. if you cant adjust the idle at all with the aac that could be the problem. gl with that you need to check the really obvious stuff first and be systematic about it. in the end you will find the problem and hopefully it doesnt require a rebuild

[worldisgrand]

I agree. I was having the same problem about a week ago and was getting frustrated. A friend told me to swap out the coolant sensor. I did that and changed the oil and now it idles perfect. With a TT also check all vac lines, intercooler connections, EVERY LAST ONE OF THEM.