Engine/Transmission (1998.5 - 2002) APPS Sensor or VP Pump?

[lancechabot]

Hello,



I am a fairly new owner of a 2002 5. 9L Dodge Cummins 2500 4wd Automatic (4 gear) trans. The truck is fully stock and only has about 130000 mi on it. The lift pump and VP pump were said to have been replaced 50000 mi before I bought the truck and the trans was rebuilt right before I bought it and only has about 2000 miles on it. Lately I have been having problems with the pedal feeling "dead" sometimes when I first start and take off in the truck (like the first five min. of running) and then it all of a sudden kicks in and off I go. I also have the same problem at about 55-65 mph when rpms are low in overdrive. I have to really mash the pedal for it to down shift and accelerate. From what I've researched these sound like symptoms of a bad APPS sensor but the only trouble codes I'm getting from turning the key are not related to the APPS that I can tell. Codes are P1693 and P1694. I will have it read with a ODB II soon to see if any others pop up. I'm concerned it may also be the VP-44 but I have no means of checking fuel pressure. What can I do about all this? Any help would be greatly appreciated. I'm also a subscriber to TDR and this is my first post... hope it pays off.



Thanks,



Lance

 

[WBodine]

First thing you need to do is check your fuel pressure, probably fine but better safe than sorry. A gauge should be available at most parts stores. Next it sounds like to me it is your APPS... Good news you made a wise decision joining TDR. A lot of people put in some hard work on this problem and we now have a solution at about a third of the price or less of original. Do a search on TIMBO he is awsome. Or you can order the same parts from GENOS. I hope this helps.

 

[lancechabot]

Thanks a TON!

 

[PBoland]

I had similar symptoms, but I had code P216 injection timing failure. I ended up replacing the VP44 this past weekend. Before parting with a grand, research all the suggestions with APPS, TPS, fuel pressure, etc…



Gook Luck!

 

[grimesja]

My money is on the VP-44, I have replaced APPS, TPS, etc... The root cause of 100% of engine related issues has been the VP-44.



You MUST install a way to monitor the fuel pressure, especially if you have a standard lift pump. Is the dead pedal interminet or continous?



If you have a good local diesel shop, they may be able to bench test the VP-44.

 

[SHobbs]

A dying APPS at times will not toss a code at first, a dying VP44 will in my experience. If you drive the truck long enough the APPS code will reveal itself. My experience with a dying APPS is just what you say, the truck will stumble at launch and at highway speeds IF you get it there. You can floor it and the truck will take off, let up and it will stumble. When my VP44 died the truck acted the same way except it would die at stop lights, signs or when idling. I have yet to see it die when the APPS gave up.



Unless you get a code telling you differently go simple and change the fuel filter, if it still does the same I would look at the APPS then the VP44.



Think of the APPS like a dimmer switch. Turn the knob and watch the light bulbs reaction. Basically the same principle.