You pulled #1 injector wire off, and it didn't make any difference..... didn't drop the idle. You got two injector circuit codes when you scanned it - which ones?

If you swapped out the injector with the junkyard injector, and it didn't help, seems to be pointing to the wiring???? Possible the wire to the PCM is shorted to ground? That would cause #1 to be "on" all the time and dump fuel into the cylinder.

Did you try swapping #1 injector with a differnt cylinder, and seeing if the problem moved with the injector, or stayed with the wire?

What were the codes for the O2 sensor? Did you check the fuse that supplies +12V to the sensors? Seems like maybe the MAF and O2 sensors may be missing +12V power. Blown fuse? Coincidence? Shorted wiring harness?

 

Don't they fire by "allowing" gorund to each injector?

How could I test the wires with a volt/ohm meter? I was gonna test their resistance yesterday but I realized I didnt know which connector or pin on the PCM it would be.

Now last night the engine locked up in our '92 Z71 I was driving (on borrowed time) and crap is getting piled up!

 

Yes.... the PCM "grounds" the circuit to fire the injector. If the wire to the PCM is shorted out to ground, the injector will always be "on". The injector would probably get pretty warm.

With the ignition on, pull the injector harness connector off. One wire (from one of the fuses... think its pink, but I don't have my wiring diagrams handy) should be +12V referenced to a chassis ground. The other wire (from PCM) should be 0V, and when you check the resistance to a chassis ground, the resistance should be infinite. If the resistance is low, the wire is already grounded. This is just a guess at a possible source of the problem.... no guarantee that is what it is.

 

Its raining cats and dos so I cant do a whole lot of troubleshooting right now.

I took my voltmeter an set it on 20. With the key on it read 11.75 at the #1 injector harness with the harness unplugged and after the fuel pump was done priming.

I suppose I need to trace that wire back to the PCM and see if its burn/broken?

Anyone know which connector and pin on the PCM the #1 injector ground is?

Thanks
Graham

 

#1 and #3 and #5 check the same voltage and resistance. 3 and 5 are functioning cylinders. Im thinking about going ahead and getting a PCM to try!

 

Bad PCM!

....fyi.....