97 7.3 rough idle when warm

[paulr4]

My 97 7.3l powerstroke van has started to idle rough but only when warm. At cold start is sounds/feels normal. At any RPM other than idle it also sounds and feels normal. When idling warm it is very rough, periodic vibration that feels like it is stalling. It has not actually stalled, there is no smoke at warm idle. Some smoke at acceleration from idle but none accelerating at higher rpms.

From other posts the cam position sensor might be worth replacing. It also smokes alot on cold start until warmed to normal. More smoke than there used to be on start up before the rough idle. It has 305k on it already so some smoke should be ok. Any ideas?
Thank you

 

[towcat]

how's the wiring harness under the valve covers?
My company '97 F450 has the same problem too but it's intermittent.
I'm not turning it in for service until the damn thing drops tho.
It's backup is a '04 F550 6.0......this truck has left me walking more than any other truck I've driven.

 

[Mike]

Those symptoms sound alot like IPR valve orings.

 

[Andylad13]

isnt ford recalling all 7.3 powerstrokes for the cam sensor?

 

[tonkadoctor]

isnt ford recalling all 7.3 powerstrokes for the cam sensor?

Yes they are

 

[tonkadoctor]

Those symptoms sound alot like IPR valve orings.

Or possibly injectors going south.

 

[Mike]

isnt ford recalling all 7.3 powerstrokes for the cam sensor?

CPS works or its doesent, there isnt an in between fail stage where it makes the engine run poorly.

 

[Double-S-Diesel]

CPS works or its doesent, there isnt an in between fail stage where it makes the engine run poorly.

I have to disagree with that, had my old 96, check engine light came on, started pouring white smoke out, then wouldnt rev above 1000 rpm, hobbled it to the shop, then shut it off, and retsrted and was fine, CPS was the problem.

 

[trackspeeder]

CPS works or its doesent, there isnt an in between fail stage where it makes the engine run poorly.

Some do and some don't.

I had two CPS's take the slow death route. Frst time went to the dealer. Second I drove home.

 

[trackspeeder]

Dose sound like an IPR issue.

 

[Mike]

The CPS is a Hall Effect Sensor and there is a basic description in that link how they work. Basically its a magnet and a pickup, when the magnet passes the pickup it sends a signal. On/off/on/off/on/off........ better known as a digital. When the on/off cycle is interrupted the IDM shuts down the injectors.

Now, as with most electronics, weird things can and do happen and I think the killer of the Ford CPS probably lies in its operating environment of excessive heat and vibration. That may cause some of the on/off cycles to become skewed, or so the PCM/IDM believe so.

Over at SDD there is a pretty good thread concerning the CPS. See it HERE.