Crankshaft Position Sensor Harness

[Double D]

Greetings All

I have a 2000 Tahoe Z-71 with a 5.7 vortec with 250,000 miles and Ive been chasing down a backfiring issue under acceleration and coasting at 45-70 mph that wont set a code other than a misfire code. so far Ive replaced the plugs, the coil which was bad , the cap (wore out), rotor, cam position sensor on the distributor, map sensor ( plugged up ) , the temp switch, throttle position sensor and today I replaced the crankshaft position sensor with the 100.00 Delco pro unit.

There is a 2 pin plug that's at the end of the crankshaft position sensor harness that dropped down and was covered in engine / road grime. I have no idea where it plugs into but it appears that it has not been plugged into anything in years. The plug body is red plastic. Does anyone in the group know where this 2 pin plug is supposed to be plugged in at ? or is it just not used on my particular truck ?.

There's no slop in the distributor gear and the plug wires are good so I'm hoping that the replacement crankshaft position sensor solves my problem. All the connections to the ECM are good.

The engine starts up fine but the backfiring under mild acceleration and while coasting happens in both open loop and closed loop modes and I would have thought that the ECM would have set some kind of code for the clogged MAP sensor or the TPS sensor which had a deteriorated casing but Scan XL pro just shows me misfiring codes. Ive been replacing one sensor per week trying to nail this thing down because normally I can track down the problem within an hour but this thing really has me doing some serious head scratching

Thoughts ?

Thanks
Double D

 

[Schurkey]

2000 Tahoe Z-71 with a 5.7 vortec

Ive been chasing down a backfiring issue under acceleration and coasting at 45-70 mph that wont set a code other than a misfire code.

"Backfiring" into the intake manifold, or into the exhaust?

Ive replaced the plugs, the coil which was bad , the cap (wore out), rotor, cam position sensor on the distributor, map sensor ( plugged up ) , the temp switch, throttle position sensor and today I replaced the crankshaft position sensor with the 100.00 Delco pro unit.

Plug wires? What "temp switch"? Do you mean the temp sending unit for the instrument cluster guage, or the temp sensor for the computer?

Cranking compression test? Leakdown test to verify valve sealing?

There is a 2 pin plug that's at the end of the crankshaft position sensor harness...

No idea. Sorry.

the plug wires are good

How did you test them?

backfiring under mild acceleration and while coasting happens in both open loop and closed loop modes

What are the short- and long-term fuel trims WHEN IT'S BACKFIRING?

Ive been replacing one sensor per week trying to nail this thing down

Replacing sensors without appropriate diagnosis is nuts.

 

[xXxPARAGONxXx]

A random red connector hanging down...yeah, that sounds like the EVO connector. No worries; it's not harming anything just hanging there. Your power steering EVO system probably doesn't work just like most everyone else's.