I posted this initially under the technical forum but I realize that doesn't get a lot of traffic so hear goes...

Symptoms: Car has a long standing CEL. Ran the codes as random missfires for each cylinder and fuel too rich. Warmed up and sitting in neutral, everyone tells me the car sounds like its missing. If the car is up to temp and at a stop light, it runs slightly rough. When the fan kicks on, the idle goes bonkers and the CEL blinks. When the fan turns off or you take off from the light, the CEL goes back solid. Also, under various conditions if you blip the throttle in neutral the car will stumble and die.

Things I've checked: Today with the car running i pulled each injector plug starting from the firewall forward. As I pulled each one, the car stumbled accordingly until I got to the last one. I pulled it and the motor did not stumble at all but the CEL inside did start to blink (I'm pretty sure it had nothing to do with the symptom I described above, I verified this multiple times). Next, with the car in neutral I put a load on the motor up to about 4k with the injector plugged in and with it unplugged and there was a discernible difference. Motor was not eager to rev with the injector unplugged and sounded like it was straining.

From that test, it looks like that cylinder for whatever reason is not firing in a low rpm/idle condition. I had the same symptoms a few months ago and had the injector replaced with a known working injector so I can pretty much rule out the injector itself. That only leaves the spark plugs and the coil pack, both of which I'm going to attempt to check this afternoon after work. I'm also going to pull the the o2 and see how bad they are.

Any ideas of what else to check? I have a few hours before I head in there and I'd like to explore every possible option.

 

have you done a compression test yet?

 

nope. Guess that's next on the list

 

I'm guessing coil pack.

I had the same symptoms on my truck. While driving along, CEL goes off, truck loses power (hesitation) and almost stalls while in traffic

 

Isle2k, thanks for the story.

I pulled the spark plug, a tad bit on the rich side but other than that its fine. That only leaves the coil pack.

I also attempted to pull my o2s but could only get the secondary out. Pitch ****ing black. I'm assumping the primary is fubar'd as well so I'll be buying new ones of those as soon as I figure out what's causing the goddamn car to run so rich in the first place.

 

ecu sounds suspect.

 

any updates?

 

Not yet, I haven't had a chance to get under the hood again. Hopefully this weekend.

I've narrowed this down also to heat. When the temp is "hot" outside (anytime between 9am-7pm here in Tampa) this is when the idle starts acting up.

 

Believe it or not, might wanna check your battery out, when they start going bad, they put tremendous "load" on your electrical system and it makes it difficult to keep the car at idle when the battery is consuming so much juice from the alternator.

 

I just installed a new Pioneer Premier 880PRS...it has a built in voltage monitor. At idle the car makes a solid 14.1v. Readings stay consistent when you turn on accessories such as lights, AC, etc etc. so I don't think its that.