Serge or miss

[nitrousjunkie347]

OK, my truck is back in TX and my dad is driving it while I'm stationed in HI. He is telling me that while driving at a constant speed, it starts to jump and serge. Almost like it is a tps issue. I replaced the tps about a year ago. The odd part is,he says that if you use the cruse control it stops. I know he recently replaced the cps as well as the alternator. I'm stumped as to what it could be now. I know this is a vague description, but let me know what you would like to know and I'll try to get more info. Oh, I know the alternator is a pos autozoner and I think the cps is from ford. Thanks

 

[golfer]

If it is how you are describing it..and it isn't a misfire...then it sounds like it could be related to the HPOil system...

if the truck has a tuner or chip on it, remove it (or lower the setting to something mild)...see if that solves the issue.

A lot/all tuner & chips increase ICP pressure..and at steady pedal...you are most likely to have the on/off on/off surging as the computer/tuning overshoots and undershoots the desired ICP pressure.

you/he could verify this if he has a way of monitoring ICP pressure...either with a scan tool or a mechanical gauge.

if it is NOT tuning/chip related...then without a whole lot of diagnostics...I would first CHECK to see if the IPR nut has fallen off of, or is loose on the IPR valve in the back of the HPOP...

if IPR valve is intact/tight...then replace the IPR.

here's a link that will describe how to check ICP pressure...but disregard the WOT runs...and just watch the ICP pressure during steady state driving for pressure fluctuations.

http://www.swampsdiesel.com/site/how_to_pdf/pdf/hpop.pdf

if the IPR doesn't fix it..and you still have the pressure fluctuations..it can take much more indepth diagnostics to determine which other component(s) are causing the pressure spikes and the surge. As an injector (poppet valve), sticking, low pressure oil problem, HPOPump problem can (all) cause similar spikes in psi...even low oil level in the pan can cause these/similar issues

 

[nitrousjunkie347]

Thanks for the info Golfer, I'll pass it along.

Is there anyone in the Corpus Christi/Odem area with AE, that wouldn't mind helping out getting this figured out??

 

[Illinois7.3]

I've been having the same symptoms for a year or more now. I switched the tps with the Dorman replacement and it "solved" the problem. 6-8 months later and same symptoms. Decided maybe the replacement was bad and went with another Dorman. now 6-8 months later the problem is back. I don't know if the Dorman units are that bad, or if the sensor is somehow masking the real culprit. As far as I know Ford wont sell the sensor itself, just the entire pedal assembly. If you get anything figured out post it up!

 

[TARM]

Maybe get a Ford one off a salvage yard truck. I know Dorman UVCH are suppose to be crappy as well compared to the Fords. Even though the Ford ones are still sub'd out and made in China they seem to have better QC. Its likely the same deal with this part as well.