I hate to beat a dead horse but have you checked the fuel pressure light to make sure it is good, some members might no agree with me on this but unplug the lift pump and start the truck if the light comes on then you know its working because you have no pressure, once you find out immediatly shut the truck off so you dont harm your IP...I just want to make sure that light is good

 

We were contemplated this when we first installed the light...but, the way the light (an LED) is hooked up, it is on whenever the truck is not running. Basically, because this LED draws nearly nothing, we have it hooked up from positive on the battery, through the LED, and the ground is through the pressure switch...the light goes off when you flip the key (wait to start, lift pump primes system), comes back on sometimes (depending on the wait to start length of time), and goes out as soon as the truck is started.

This makes for a self-check every time the truck is started, and makes an excellent anti-theft light (although I'm not sure who would want to steal this thing).

 

 

And I really do appreciate all the input, hope I don't come off being cocky...

I just spoke with Cummins...they list six sensors for this engine...coolant temp, cam position, crank position, oil pressure, pressure sensor-intake manifold, and an air temp sensor...I told him to order the last two, but he said one (the MAP) may have two different numbers depending on the intake. He's going to call me back...

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Well, the numbers for one combined, and the number for the other updated...I'll post both when I get the parts.

The MAP is $52 and the IAT is $43 for those curious...

 

sweet, hopefully itll help fix your problems. part of me wonders the condition of your turbo as well, them damn stockers do wear out and leak pressure over time. I dont think this would be your problem but just something else to think about.

 

Well, finally got things swapped and did the calibration of the APPS...the IAT was extremely dirty. The MAP seemed to be working fine...the IAT was also found to be within specs after cleaning...it was almost "wet" with dirt (and the intake hose is dry).

While trying to calibrate the APPS, the starting voltage was only 0.290VDC...the required voltage at the APPS was 0.560VDC, but the maximum voltage we could achieve was 0.440VDC (fully advanced). What does this indicate?? Should this be a concern??

While probing the APPS wire, I noticed the ground from the firewall to the PCM was corroded at both points. We cleaned both of those points and soldered the wire to the ring terminal. Not sure if it made any difference, but it was amazing the corrosion on the PCM...sanded quite a groove into the case before I actually got metal.

We also recalibrated the pedal (disconnected batteries and did the pedal thing)...

The bottom end power was noticeably improved, as was throttle response. I'm still concerned about not being able to obtain the corrected APPS voltage after recalibration.

 

If you can't reach the required voltage on your old APPS, I'm afraid it's time for a new one.

 

A lot of people do this adjustment and screw up the idle validation switches... You can't just be twisting the APPS back and forth. Just as bad as playing with the set screws....



So as you twist it one way or another you mess with the 2 idle validation switiches too. This effect a couple of things like Exhaust brake operation, etc...

 

You point out the issues doing so, but I don't see you offering a corrected method of recalibrating the APPS?

I followed the directions without any issues other than not being able to obtain the desired voltage.

 

https://www.dieselbombers.com/24-val...ting-apps.html