Evertight

When at highway speed 110k/70mph, set cruse on flat highway, no wind & a
slight serging happens? Tach moves just slightly up & down & if you just lightly lay your foot/toe on the pedal, it moves slightly up and down also?
You can also hear the turbo just start to wined up then become quiet.
Is this the start of a failing APPS??

1-5-3-6-2-4

I dunno why, but my HRVP surges BAD in cruise, same as you describe only far worse. but with the cruise off, throttle response is rock steady. 'cept at idle but that another story all together.

crobtex

Could be. Try the APPS reset and recal and see if they help.

Reset: https://www.dieseltruckresource.com/...n&onlynewfaq=1

Recal: https://www.dieseltruckresource.com/...n&onlynewfaq=1

RowJ

Welcome the the DTR!
The surging you describe is usually associated with some fueling mods....a chip, box or larger injectors ... which causes the cruise control to over correct. Possible?... Is truck new to you?
Fill in your signature so we know what year/tranny/mods, etc. you have.

RJ

Truckman

Please fill out your Sig..
Does your cruise NOT stay at the set speed? ( set it at 70 MPH and slowly creep up to 75 or so?) Or does it surge to 75 then back to 70 and so on?
If it creeps up past the set speed there is a TSB on it,,I will look for the number,,Depending on the year of your truck..

TSB #18-08-99


Symptom/Condition:
Some customers may complain that their vehicle speed control system may be too busy or drift more than 2 mph below or above the initial vehicle set speed. Vehicle load and road / terrain conditions may impact this issue.

The new PCM software improves the speed control system sensitivity so that the vehicle speed remains closer to its set speed with fewer engine rpm oscillations.


Hope it helps. Good Luck,, I did it to mine and it worked great..

Evertight

Thanks for the welcome, still new at this.
The truck speed stays the same, just the motor surges for about 1.5 sec.

Maybe it is the Predator? I phoned the tech rep at predator and he said he has never heard ofthis before, and it must be something wrong with the truck.

I will check out the TSB recall. Had the truck since new.
Thanks for the help.

Truckman

I see automatic ,, Is it coming out of OD and going back into OD (lock up)

Evertight

No the trans stays in OD & the TC stays locked up. Its not a major thing just a pain in the but. If there is a simple fix I'd like to find it. Also just had
new sensors replaced in trans while in for trans service, but it was doing the slight serge before the trans service.