Engine/Transmission (1998.5 - 2002) Not able to fully calibrate APPS??

[steved]

Trying to track down some bottom end sluggishness in my dad's 99... we recalibrated the APPS today.



The voltage at the PCM was 0. 290VDC, the APPS was marked at 0. 560VDC, but even at full advance of the APPS we were only able to obtain 0. 440VDC at the PCM.



We then recalibrated the pedal to the APPS (disconnecting batteries, running pedal) afterwards... but we never checked the voltage after doing that. Would that have affected the voltage??



Is this any indication of impending doom??

 

[Bob4x4]

Trying to track down some bottom end sluggishness in my dad's 99... we recalibrated the APPS today.



The voltage at the PCM was 0. 290VDC, the APPS was marked at 0. 560VDC, but even at full advance of the APPS we were only able to obtain 0. 440VDC at the PCM.



We then recalibrated the pedal to the APPS (disconnecting batteries, running pedal) afterwards... but we never checked the voltage after doing that. Would that have affected the voltage??



Is this any indication of impending doom??

If it is very sluggish til about 2k rpm. . suspect the boost sensor first. Assuming the fuel psi is good.



Bob

 

[PC12Driver]

Two things to keep in mind with the APPS on our trucks: the only thing the APPS commands on our engines is the desired RPM, and the ECM self adjusts for the minimum and maximum voltages from the APPS. So, if after your recalibration you can get a normal idle (850 rpm) and can get to redline in neutral, then your problem won't be with the APPS.



Don't worry about what the tag says if you're tracking down engine performance problems. It's only means something to the PCM (shifting and TC lock points on auto trucks), which doesn't self-calibrate. And no, the voltage outputs won't change after recalibrating the way you described.



I'm with Bob - I'd look somewhere else, possibly with the boost sensor. When you say bottom end sluggishness - is that with our without smoke?

 

[steved]

Two things to keep in mind with the APPS on our trucks: the only thing the APPS commands on our engines is the desired RPM, and the ECM self adjusts for the minimum and maximum voltages from the APPS. So, if after your recalibration you can get a normal idle (850 rpm) and can get to redline in neutral, then your problem won't be with the APPS.



Don't worry about what the tag says if you're tracking down engine performance problems. It's only means something to the PCM (shifting and TC lock points on auto trucks), which doesn't self-calibrate. And no, the voltage outputs won't change after recalibrating the way you described.



I'm with Bob - I'd look somewhere else, possibly with the boost sensor. When you say bottom end sluggishness - is that with our without smoke?

Without smoke...



Recalibrating the APPS made it more responsive and also did help with the bottom end sluggishness. Top end is great, it would probably run along my 04. 5. Although we didn't try a nuetral WOT, the idle is still correct and the truck will pull to redline in a WOT run (in gear, its a manual)...



I pulled the IAT, it was dirty. We replaced both the MAP and the IAT (anyway)... the IAT (cleaned) was reading correct ohms.