I recently rebuilt my 1990 k1500 350 tbi and upgraded to vortec heads. I can time the engine to 0 degrees with the ecm wire disconnected and it runs good at idle, however, when i turn the truck off, unplug the battery and connect the ecm wire, the timing just stays at 0 degrees and doesnt advance it like it should. I've replaced the ECM, have had two chips burned for it, replaced the distributor, and it still doesnt advance the timing when i plug in the ecm wire.
Im not sure why the ecm and distributor are not communicating like they should. any advice would help!

 

I recently rebuilt my 1990 k1500 350 tbi and upgraded to vortec heads. I can time the engine to 0 degrees with the ecm wire disconnected and it runs good at idle, however, when i turn the truck off, unplug the battery and connect the ecm wire, the timing just stays at 0 degrees and doesnt advance it like it should. I've replaced the ECM, have had two chips burned for it, replaced the distributor, and it still doesnt advance the timing when i plug in the ecm wire.
Im not sure why the ecm and distributor are not communicating like they should. any advice would help!


1990 k1500
350 tbi vortec conversion
chip by motorvations
4x4

 

There are two ground wires on the engine. One attaches to the thermostat stud. The other attaches to a bracket bolt to the left (drivers side) of it. Those two ground wires absolutely HAVE to be separate from each other or weird things happen to the ECM.

 

The two grounds are in separate locations at the front of the intake... still same issue. Nothing changes at all when I plug the ecm wire in...

 

Does the check engine light come on, showing the computer is connected? Did you try just turning key to the on position for five minutes before starting, giving time for computer to register all sensors. If not unplug battery for one minute, connect battery and try this. If this doesn't work, does the engine check light come on? What are the error codes?