Engine/Transmission (1998.5 - 2002) Erratic Idle after using cruise control

[RDMueller]

I've been experiencing an unusual problem with my truck and wonder if anyone else has seen this or has any ideas. After driving for a while (at least 15-20 miles) with the cruise control engaged, if you then pull off the highway and come to a stop the engine will experience a very erratic idle, jumping around between 850-1200 rpm. It will continue to do this until you shut down and restart, after which it will operate normally.

A few additional points:
- this only happens after driving with the cruise control on
- the cruise control itself works perfectly
- there are no codes
- there are no other problems with the truck
- it seems to be more pronounced in warmer weather
- the engine does not run rough, just an erratic idle
- if you depress the accelerator, you can get it to run at a steady higher rpm

The truck is a 2001. 5 with a 5 speed and is stock except for a Raptor 100 lift pump. It has 230K miles on it.

 

[JLandry]

How old is the VP44?



Just curious... are you monitoring the fuel pressure?



John L.

 

[RDMueller]

Yes, fuel pressure is fine. I don't know the age of the VP44 as I'm the second owner of the truck. It is not original however as I've noticed a sticker on it, "Proudly rebuilt... " I don't think it very likely is related to the VP44 though since the problem only appears after using the cruise control. I'm am familiar with the various symptoms of a failing VP and haven't experienced any. I was doing a bunch of reading last night on this forum and do see some evidence that the APPS may be the culprit.

 

[JLandry]

If the engine is otherwise running normally (not a rough idle when this occurs) and it's only the rpm jumping around, then yes, the APPS could definitely be the culprit. Worst case if it doesn't fix the problem you'll have a spare one... they eventually go bad.



Please let us know how things work out.



John L.

 

[JDriscoll]

My 02 does something similar, after driving with the cruise control on the truck will idle at about 1100rpms. The idle is steady, just high. I've also been having some trouble with the APPS so I'm pretty sure the two problems are related. After the cruise control has been on for a long period of time, usually at least an hour, when I tap the brake pedal the accelerator pedal goes dead. The truck idles fine, the pedal just doesn't work. 9 times out of 10 it happens at a stop sign at the end of an off ramp. I usually just idle off to the side of the road and shut the truck off for a few seconds and everything works normally when I start it up again. It is starting to happen more frequently and I'm looking at replacing the APPS with the one from the Geno's catalog.

 

[bromano676]

I had the exact same problem. High idle after cruise was on. Finally after while I got a dead pedal and set some codes. I put the APPS from TIMBO in and have not had an issue since. Almost 3 years now. I think.

 

[HBarlow]

Most likely caused by a failing APPS.

 

[RDMueller]

Thank you everyone for the help. I have ordered an APPS and will report back with the results.

 

[RDMueller]

Follow up - I replaced the APPS and it solved the problem. Quick, easy fix!