i have an 01 cummins 6 speed.. Gradually over the past two months i have had a throttle/power issue that has gotten worse. It always happens now when first started and driving in these cold temperatures.

It feels like a clogged fuel filter would feel. Power will be normal then it bogs down for 2-4 seconds and then returns to normal..this happens constantly and is the worst when cold, once warm it will do it slightly but not near as bad/ or frequently. This is just city driving, and around 1500 rpms in 2-4th is always the worst. If a push the pedal further it will always accelerate and doesnt bog down. but holding steady at a higher rpm it can still do it.

Once on the freeway and on cruise control it will never do it. I have a constant fuel pressure between 12-15psi from my FASS. So i dont really think its the filter. However i have new filters to go in in the next week.

There are no codes on the odometer. Could this be something with the grid heater circuit? or could it be the aps? also, even tho my fuel pressure seems good, could it be a filter? however then i would think it would still do it at crusing speeds on the freeway.

i am leaning towards just replacing the aps from alot that I have read. I dont really think this is a vp issue. But maybe..

Any advice?

Thanks, Scott

 

How many miles on the truck? The grid heaters shut off at 15mph if I remember right, so if the problem exists over that mph you could probably rule that out. When the APPS fails (in my experience) you have to let off the throttle and then reapply it to regain your throttle control. Does the problem occur at the same spot in the pedal? VP is always a possibilty on these things but a little more troubleshooting needs to be done before changing that out! If you have access to a scan tool, that would really give you some valuable info on the problem.

 

Not trying to be a smart a$$ here, but did you cycle the key, or do you think the codes just appear in the odometer window? Sounds an awful; lot like "DEAD PEDAL" to me.

 

Truck has 167,000 miles. On its original VP44. Fass has been on since 60,000 miles.

yes it does it over 15 mph, so it must not be related to grid heaters. It seems to do it only when i am partially on the throttle. Which is always around 1300-1700 Once i push the pedal further it accelerates like normal.

I never have to let off the throttle or anything like what I have read about on here. It just feels like a reduction in power that intermitently happens.

Yes i cycle the key correctly, it gives me no codes. Do any of the major auto parts stores carry a scanner that can be used on our trucks?

With a vp44 going out wouldnt I experience this condition when on the freeway and running 2+ hrs over mountain passes at up to 20lbs boost? It has never done it out on the freeway. I normally always use cruise control and run around 1700-2000rpms.

It is always the worst when it is first running and cold out. Once fully warmed it barely does it at all.

-Scott

 

When my VP went out it did the exact same thing. Any auto part store should have a scanner you can use.

 

Ok well i will get it scanned and see if anything comes up. if its a vp44 then I will replace it, not really a big deal, i just dont wanna throw parts at it trying to figure it out.

A better way to explain it i think would be to say it is more like a surging feeling. i have to pull a major hill either heading to work, or headed home from work.

So the truck is normally only running for couple minutes when i pull these two hills. When driving up these hills it does the surging the worst. i always try to keep the revs down around 1500 in either 2nd or 3rd gear but that seems to make it the worst.

-Scott

 

At 167,000 you're already doing better than most people! Mine started getting weak and idling rough at around 144,000. I didn't want it to leave me on the side of the road so I stuck a new one on for peace of mind.

 

Got it scanned for codes, and there are none.. I will change my filters next, then maybe get a new APS. Not really sure what else to look at.

-Scott

 

My '01 is starting to do about the same.
At low steady throttle input it seems to get little "fish tugs" like a bad fuel filter but I can look at my guage that is at 20PSI. It doesn't
bog down for a few seconds, much shorter, like little stumbles or fluttering of the RPM
It does it more when it is cold.
I also never seem to have any power surge/restriction when pushing the pedal all the way down, only when trying to holding half throttle.
Almost feels like my Edge programmer is toggling between power settings.
I have 167,000 on my truck and judging from the lift pump in the tank it had a VP-44 installed by Dodge ealier in its life.
I think I will turn my Edge programmer off today and see if it fish tugs in stock mode as well....

 

Yeah that sounds pretty much the same as what I have going on. I have tried the edge on other settings and it still does it, I havent tried it on the stock setting yet tho. Does yours do it when your at cruising speeds, or on cruise control?

-Scott

 

Mine does the same thing, slowly getting progressively worse. No edge comp, but I do have the puck. I was thinking it may be a low voltage electrical issue.

 

Have you guys tried an APPS reset.
Could be a worn Throutle position sensor.
I just put one of Tims TPS and also put on a BD Apps noise isolator capacitor

 

1. Use a scanner. Don't rely on the dash readout.
2. research VP but do a proper diagnosis.
3. report back or research codes yourself.
4. do not install parts until you properly diagnose.

You are pointing at some expensive parts that may be unnecessary and will not fix the problem unless they are necessary. Parts throwing makes a good professional mechanic inexepensive in comparison.

 

Yeah i had my friend run his scanner on it. there were no codes found.

-Scott

 

I drove on the stock setting of my Edge/Juice tune and it still "fish pulled" under low throttle input and RPMs 1800-2000.
If you stepped on it, it runs smooth and with a lot of power.
It always starts right up hot or cold.
I will let my buddy throw it on the scanner at his shop next week and report back if I get any codes.
It is worse when cold first thing in the morn. [30ish F*] but, I can feel it lightly surging when warm as well.