rpms wont go over 2,000

[hoosier35]

i've had my transmission rebuilt a month ago, new apps (timbo), cleaned and make sure i had good connection for my MAP and AIT sensor. No CEL. i've done the key trick and p1693 pops up so i hook up my scanner and i get no codes. i've put on all new HD battery cables and make sure all my grounds are good plus have done W-T's ground mod. i have no tuner. i have a FASS 150 and my fuel filters were changed a couple months ago and it has been the same before and after fuel filter changes. my truck drives fine from idle to about 2,000 rpms. when i stomp on it i've gotten it to maybe 2,200rpms but it feels and sounds like it's redlining or working really hard. now my abs and brake light are on but my speedo and tach are accurate. on the highway i can't really go faster than 70 and it'll be at 1900-2000 rpms and just feels like the engine is at way higher rpms and is working really hard. no matter if i put it in park or neutral and rev it, it still sounds the same with the rpms shown on the tach. i'm lost now trying to chase this problem. 

[Mopar1973Man]

23 minutes ago, hoosier35 said:

my truck drives fine from idle to about 2,000 rpms. when i stomp on it i've gotten it to maybe 2,200rpms but it feels and sounds like it's redlining or working really hard.

 

This is called limited pedal typically caused by excessive AC noise from the alternator caused damage to the ECM. First thing is to do the AC noise test of the alternator. Replace the alternator if needed. Inspect all battery cable repair or replace any battery cables that are damaged or corroded. Now you might want to do @W-T ground wire mod. This will keep the AC noise from jumping into the ECM, PCM and VP44 in the future. After all this done and the problem still exist you need to send your ECM in for repair. 

 

 

 

 

[hoosier35]

i'll have to test for ac noise but i have done the complete ground mod and just replace my alternator a couple weeks ago. i have all new upgraded battery cables for over a month and none of this has changed it all. 

[Mopar1973Man]

Then most likely the ECM has already been damaged. You can try one thing but I'm not sure if it will do much good. You could go to a dealer and have the ECM reflashed and see if that fixes the data tables. 

 

The only other wild idea is to watch live data from the ECM and see what the engine load and MAP sensor are doing. It might give clues. 

[hoosier35]

yeah i was thinking about the whole reflashing ecm thing. yesterday i did plug in my scanner and pull up live data while i drove. what would my MAP numbers be?

[Mopar1973Man]

Typically 28.3 to 37.3 for value normal live tools can't math out real pressure numbers.

[hoosier35]

At idle I’m at 59 inHg 

[Mopar1973Man]

Any error codes? Could be an overboost condition creating this...

[hoosier35]

No codes, just the 1693 when I do the key truck but no codes on scanner. Back when I first got it 3 years ago, it would throw the code about the MAP sensor on and off, I replaced it once and then back before I rebuilt my trans a couple months ago it threw it again and that’s when I cleaned both MAP and AIT sensors, made sure my connection were good then I erased them and they haven’t come back sense. The MAP sensor code is the only one I’ve ever seen come up. 

Edited August 2, 2018 by hoosier35

[Mopar1973Man]

Which one?

P0234, P0236, P0237 or P0238

[hoosier35]

I don’t remember the exact code sorry but I remember is was a low voltage one

[Mopar1973Man]

Here you go some reading material...

 

[hoosier35]

Ok thanks, I’ll see what I can do tomorrow or this weekend and I’ll comment what I find

[Mopar1973Man]

Just remembered that @dripley also having weird sensor issues as well every time he fiddles with the loom he gain back function. Dripley can post up his findings.

[dripley]

3 minutes ago, Mopar1973Man said:

Just remembered that @dripley also having weird sensor issues as well every time he fiddles with the loom he gain back function. Dripley can post up his findings.

Now if I can just find the time. I just lost next week off but will be much closer to home after that.

[hoosier35]

So I figured out my scanner to scan for “enhanced oem codes” or I guess stores codes, it pulled up p0177, p1694, p1693. The p0177 is water in fuel, I have a FASS 150 and took out the WIF sensor and wrapped it up in tape. 

[Mopar1973Man]

Hop over here and read up.

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/51_engine/obdii-error-codes_94/