How would the Idle air sensor effect the high speed operation? My truck idles fine, actually it runs fine until it warms up. Going to spend my xmas checking the cats and o2 sensors.

 

It sounds a lot like some problems others have had. Really rough running, cutting out, etc. It was providing bad info to the PCM. They replaced it and fixed the issue. It may not be exactly the same as what you're dealing with but you've seemingly replaced everything else. My cat has rattled for years and I've never had these issues.

 

It has to be some simple thing, I replaced my pcm witha known good unit, same results. going to try the ias next

 

That was it. Unhooked the IAC and she runs fine. Drove around for 40 min without a problem.

 

It was the Idle Air Sensor on the back of the throttle body? Weird huh? But cool that you found the source of the issue.

 

Yep, that was it. Unplugged it and it ran fine. I miss the old days when problems were easy to find.

 

Glad to hear that you found your problem, 72pp29. I pulled the IAC connector today (12/27) and the engine still went into it's fit. I put dilectric grease on the connectors of the IAC, TPS, and MAP while I was under the hood as well. After I did that, I started it back up and itworked through it's fit and ran fine so I'll have to wait for the engine to cool a little to do some more diagnosing. If it cools some, (half hour or so) I can start it back up and it will enter it's fit again fairly soon.

 

Kid, you may want to check the iac before buying a new one. pulled mine today and it had carbon build up on the plunger. It was working, just couldn't seat. I can see why you were getting a good scan. I replaced mine anyway, but a good cleaning of the plunger and seat, probably would have worked.

 

The iac wasn't the problem after all. problem is back and it's worse. Let me down on my way to work, unplugged thw iac, didn't help. After work it started and ran alittle rough, as soon as it warmed up, started bucking and missing again.

 

damn, sucks to be you, tkid. i was thinking, youve been checking to see if your injectors were clean... did you check to see if they were leaking? unburned fuel can cause problems with cats and o2 sensors. a leaking injector would still fire like its supposed to but still pour fuel inbetween

also i had read someones thread about the timing chain having nylon in it that can strectch and maybe throw the timing off. i think it might have been one of the indy guys (rm indy or indy ram man)