Engine/Transmission (1998.5 - 2002) Extremely slow throttle response

[JHayes]

I`m trying to help a friend with his step-son`s truck. It`s a 2002 2500 6 speed . Extremely slow throttle response when accelerating and decelerating. It sets p0122 and p0236 codes. p0122 will not erase. p0236 will erase 'and then come back when truck is cranked. Installed new map sensor. We`ve tried three pedal position sensors(two were new NAPA parts. Voltages are correct on map and APP sensors. APP has been reset a number of times. When accelerator is depressed quickly, no response until almost fully depressed. Very slow depression , acceleration is much better. After engine comes up to speed, RPMS don`t start to drop until accelerator is almost fully released. Does anyone have any suggestions?

 

[dknoch]

I don't have a good suggestion, but I am currently fighting the exact same issue. Good Luck! I will let you know what I find out if you promise to let me know if you come up with something. I am actually thinking a bad wire maybe.



Dan Knoch

 

[GOTSOOT]

slow throttle-0236!

go look up the 0236 code and see if it does not say something about your injection pump not comunicating with the ECM.

 

[Mishkaya]

P0236 (M) Map Sensor Too High Too Long Problem detected in turbocharger wastegate.

P0122 of course is the APPS.

It really sounds like an APPS problem, but if you have tried that, maybe that's not the case. I would highly suggest an APPS from Timbo though (geno's sells them I believe).

Another thought would be to check your grounds thoroughly. I always sounds corny, but you might be surprised to find out just how many issues are caused by bad grounds. I would suggest this thread as a good starting point:

https://www.turbodieselregister.com.../89040-electrical-grounding-finer-points.html

Good luck.

 

[dknoch]

Finally got my truck working right, needed an ECM. Any luck with your problems?

 

[JHayes]

I'm still working on this truck as time permits. With my regular work schedule,Christmas, and babysitting grandchildren, I haven't had much time to devote to the truck. Every time I work on it, I find more symptoms. When I get up to road speed and engage the cruise control , the truck drives normally. I have checked voltages from the APPS to the ECM and everything seens tobe normal. I've checked voltages from the ECM to the injection pump and there is no rhyme or reason to the values that I get. I strongly suspect the ECM, but I'm not sure. I hate to put an ECM on it , and that not be the problem. The young man who owns the truck has new baby and very limited funds. If anyone has any more hints as to what I can try , please let me know. Thanks

 

[dodgediesel91]

where is a good place to get an ECM and if I mat not sound to crazy what is a APPS... all new to the diesel thing guys.

 

[JHayes]

APPS- accelerator pedal position sensor sensor that the accelerator cable hooks to The sensor sends signals to the ECM for acceleration and deceleration. Aiso known as throttle by wire. I haven't gotten far enough into this project to find a good source for an ECM.

 

[Bob Cochran]

Here is one source Auto Computer Exchange - Auto Computer Superstore - Cheaper than dealers and mechanics. Some have had problems with the exchange and others have not. I have had no reason as yet to use them but it is a source besides dealer.

 

[timbo]

Here's how you check it. Using a digital volt meter, look on the back of the 6 pin electrical connector of the APPS plug, it is numbered. With a paperclip, straighten it out and insert it into the back of the connector PIN # 3, (light blue wire w/black tracer). This will get hooked to the positive lead of the voltmeter. The ground lead can be hooked to the ground terminal of the battery. Turn your voltmeter to the low voltage DC scale. Your looking for about . 5 volts at idle and smooth rise to 3. 8-4volts at WOT.



If the voltage is correct and the engine rpm is,

going up and down by itself while the APPS voltage is steady,

rising abnormally slow when flooring it,



THIS IS THE SCARY ONE!

touch the throttle and it goes to 3400rpm.



This indicates an ECM problem. Some guys have been successful by getting the dealer to reload the software into the ECM. This is most times a minimal charge, it is just difficult to find a dealer that is sharp with the diesels and will even try reloading software. Most will just try to sell you an ECM.





If you are getting a 121(APPS RANGE ISSUE) or 122 code (APPS low voltage) and the ACTUALL voltage range on a voltmeter is correct. This is an indication there is a software issue within the ECM.



PAINFULLY THIS IS AFTER SOME GUYS HAVE INSTALLED AN APPS AND POSSIBLY AN INJECTOR PUMP!