starting prob., overheating, low idle--all at random times

[adwriter73]

My '94 XLT with 72K miles has been been on a suicide mission lately. It started last week on day the temp. gauge showed the engine going hot, then suddenly back down to normal, then hot again. The next day, the problem never came back. And since then hasn't. The next problem is my check engine light comes on and off while driving. I had the codes read and none of them match my Haynes manual...222 and 416. The "tech" at autozone said, "your IAC is at maximum learning capacity." So what does that mean? Another issue is at idle, the engine runs just below 500 rpms. So, it constantly is on the verge of stalling. Then, yesterday, I experienced a new problem. It wouldn't start. The engine rotated and rotated, but after 3 attempts, nothing. I tried one last time and with a little throttle, the engine stumbled to a start. I drove it home and parked it.

Where do I begin?

 

[adwriter73]

One other thing to note. After doing a few searches I saw that many suggested cleaning the IAC valve for idle issues. I did that. The overheating and now not starting issue is of more concern. I'm wondering if all of it is related to one or two things.

 

[MrShorty]

CM 222 indicates "IDM open or high or right coil pack failure" (from www.dalidesign.com/hbook/3digit.html). FYI, IDM is module that monitors and (in part) controls the ignition system. Bad information from the IDM will prevent the EEC-IV computer from knowing when to fire the spark plugs, or the spark will be weak, or other issues. Weak spark, no spark, spark at the wrong time can explain a lot of your driveability issues/starting issues. When it won't start, do you have spark? Check the wiring between the IDM and the PCM. I'm not sure, but in some cases places like Autozone can test IDM's and ICM's.
Like I said before, I don't believe the 416 is a valid EEC-IV code. Giving the benefit of the doubt, was it a KOEO code or a continuous memory (CM) code (I've assumed the 222 is a CM code, because I don't see it listed otherwise)? If it was a CM code, and it passed the KOEO test, then let's run the KOER test before dealing with this code.

 

[adwriter73]

Thanks, this very helpful. It was a KOEO code--i assume that means Key On Engine Off code. I will have them perform a KOER test. The spark plugs and spark plug wires are only a few months old, but code a bad gapping in one of the plugs cause this too? And could any of this affect the overheating issue, or was that maybe just a moment when the thermostat was stuck, as there was plenty of coolant in the radiator?

 

[adwriter73]

Problems fixes but check engine light still coming on. And it's not giving any hard codes. Replaced the IAC and the EGR valve as well as cleaned the throttle body. Runs like new. But why does the check engine light keep coming on and off. I took it in to a repair shop and after 8 hours, they are cluless as to why it is still coming on. Any thoughts?

 

[TPLYNCH]

Was the computer reset after the repairs were made (battery disconnected for a while or cleared using scanner)? Is it the same code(s) as before? Problem may not be fixed, or a new one may be rearing it's ugly head.....

 

[adwriter73]

Yes, the computer was reset. The repair shop tells me it is not giving off any codes. They think there is a short somewhere but can't locate it.

 

[liqhx2]

no continous memory codes??

 

[adwriter73]

None that they told me about. They said they would like another day or two with it to do further diagnostic checks.

I noticed this morning that it was surging a bit during acceleration. That's new. But at the same time, the engine was still cold.

 

[liqhx2]

when the CEL comes on even if it goes out later while driving the ECM will store a trouble code if it is not storing those codes then you most likely have a short or the ECM is bad good luck