Engine/Transmission (1998.5 - 2002) Throttle lost in a trance

[Red Rocket]

I have had this problem for a while, but now it is getting worse. I saw some other threads like this, but their problems didn't seem to match mine. Here is what happens:



1 Cruising light throttle, (usually) about 55 in lockup.



2 Warm days, with A/C on( not sure if it matters)



3 Push pedal to speed up, like if the 55 zone changes to a 65, the pedal will act like nothing happened, and will stay at that power setting. I can move the pedal up and down, without any reaction, but if i floor it or let it idle for a sec, it goes away and she takes off like a bat out of you know where. Here's the problem, I have a quickcheck on this, and the map and iat sensors read normal, as well as the tps reading. I had a passenger look at the qc the first couple times it did it, and she said the numbers in throttle % changed, but the mighty cummins just motored along with a mind of it's own.



4 No codes



5 No smoke or rough running, ever.



Thanks for the help.



Nick

 

[Mundgyver]

Me thinking goes with the throttle position sensor or the ECM fed by the throttle position sensor. Just a W. A. G. of course, but could be worth eliminating via some troubleshooting. Good luck

 

[BillGotthelf]

If you can hook up a tap wire from the tps to a volt meter. Run it into your cab and if it happens again see if the voltage signal from the tps changes. If it stays the same but the throttle position changes you need a new tps.

 

[Red Rocket]

Update

I washed the truck yesterday, and this morning it was running like it was firing soft, and when I started driving it, there was the white smoke that didn't ever happen before, and it was about a mile before it snapped out of it. It didn't do that again, but it did go into the slow mode a couple more times. ...



Any thoughts now,



Nick

 

[340Mark]

Hey Red Rocket I'm having the same thing. At light cruise you can almost fell the power go a little slack. If I push in the clutch and wait 5 sec. the power will come back! I even faked out the Idle validation switch on the APPS (it didn't ohm correctly) but it still does it

Thoroughly lost and tracing wires----Mark

 

[Red Rocket]

updated thread

Just to let you know, I have posted an updated thread. Do a search under my id. By the way, cummins diagnosed a new VP44.



Nick