Thats lookin' like a bad crank sensor.....

 

I ordered the part. Should be a week or so. I hope it is only a bad crank sensor, that would be nice. I find it odd that the problem existed before the rebuild and after. For sure there is something related to the crank sensor. More to come when I get the part.

 

Did you replace the sensor when you did the rebuild? It may have been bad before, and if that was a new one, may have bent/destroyed it when installing the engine. Wouldn't hurt to pull it, and have a look.

 

I replaced the old sensor but, I am pretty sure I bent/destroyed the new one installing the engine.

 

Diagnosis in next post

 

The truck is running now. It was not an easy fix.
Thanks to everyone and their input. The MT2500 Snap On scanner is the key to fixing these Gen 2s. Without the scanner, doubtful I would have been able to fix this truck and it would have been a lawn ornament for years.
The problems and what I learned.
1. I cleaned the throttle body as recommended. I kept getting a trouble code 25 - IAC circuit short. I had a few IAC laying around so I swapped them out. Code 25 kept appearing. I found a function on the scanner that allows you run the motor in and out. So I did that with the IAC not installed on the throttle body. Strange, the CEL went out and the code went away (the car is not running). I installed a used-known-good IAC back into the throttle body. I reset the truck computer and turned the truck back on. Code 25. I turned on the scanner and started the motor test. The IAC was not moving. I loosened the bolts up a little and started wiggling the part on the throttle body, it started to move. I snugged up the bolts and made sure the piston was still functioning. I went back and ran for codes, the Code 25 disappeared. The problem was the piston was not freely moving in and out of the throttle body. Lesson learned.
2. As seen in the pictures above. See the original issue. When I would reset the computer and scan for codes the crank sensor was yes. I would start the truck and sometimes I would have an issue other; times it took 20-30 seconds to show up. After the IAC was fixed I thought ok, one problem down. Yes, the truck was idling now but as soon as I took it out of park it would die. I would watch the scanner and see the crank sensor go from yes to no. When I shifted out of park it would die. I reset the computer. Crank sensor yes. Start, yes and then shift out of park, die. I pulled the crank sensor, almost impossible with the EGR tube LOL. You can see the picture above. I measured the aftermarket crank sensor and it was slightly longer than the quality one I had to replace it. Lesson learned - do not install the engine, with the tranny in and with the crank sensor pre-installed. Do it after.
3. I may have bent the bracket but surely, I damaged the wires and the case. I do not think this was the issue. The sensor itself was just long enough that it was rubbing on the metal thing that makes the timing pulses. I do know from rebuilding the tranny that there is tolerance for the shaft that hooks into the engine. That tolerance was enough of a shift to cause the sensor to hit that metal plate and stop the pulses. I stuck a scope down into the hole and rotated by hand 360 to make sure that plate was not damaged. it was ok. I made a gasket to raise the crank sensor slightly when I reinstalled it. I put the new sensor in.
4. I reset the computer. Turned on the truck. No IAC code and crank sensor yes. I was scared of success. I put the air filter thing back on and connected that vent hose to it. I started the truck and it ran fine. The big test, shifted it out of park, Reverse - ok Drive-ok. I am scared to go start it again tomorrow. It might be broke again LOL
Summary. Code 25 may be the shaft on the IAC is not moving but, the part is good. Crank position sensor may be rubbing that metal plate. You might need to shim the IAC and also the Crank position sensor.
And, if you are having electrical problems, find someone with a MT2500.

Thread Closed!

 

Good to hear you had success. If the code 25 returns keep in mind it is "25 A shorted or open condition detected in one or more of the idle air control motor circuits" so it can also be a (intermittent) wiring problem.