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i have a 94 camaro with a 3.4 L , no injector fire on 2,3,4. swapped with a good known pcm and same thing.
car has no codes. injector pw is 10.1, fuel trim 128, map volts2.3. baro. volts at 5.0. any help would be great!

wfo44 wrote:i have a 94 camaro with a 3.4 L , no injector fire on 2,3,4. swapped with a good known pcm and same thing.
car has no codes. injector pw is 10.1, fuel trim 128, map volts2.3. baro. volts at 5.0. any help would be great!

My first check would be to see if there is power to the pink/blk wire on the affected injectors. I doubt this is the issue. Fuse 10 feeds 2, 4 and 6 while fuse 9 feeds 1, 3 and 5. If I had power to the affested injectors, my second step would be to check the harness between the injectors and the pcm. 1,2 and 3 are right next to each other at the connector.

checked the wires for the injectors at pcm and no ground from pcm , was wondering if crank sensor st the balancer runs injection pulse?

wfo44 wrote:checked the wires for the injectors at pcm and no ground from pcm , was wondering if crank sensor st the balancer runs injection pulse?

Yes, the crank sensor does control injector pulse. it also controls ignition indirectly. Are you missing spark on the same cylinders? perhaps a damaged sensor or shutter?

You could scope that sensor to see if it was bad. I have a waveform of what it should look like.

whats puzzling me is there are 2 crank sensors i know the one in the block operates ignition and rpm . so i am thinking the other operates injection pulse

wfo44 wrote:whats puzzling me is there are 2 crank sensors i know the one in the block operates ignition and rpm . so i am thinking the other operates injection pulse

Sort of.....the 3x signal goes to the ignition module, so it's running the ignition cycle but it also feeds that signal to the pcm as well. The 24x signal is there to fine tune things...better resolution. Then there's the cam sensor which sends the sync pulse to start the injectors in the proper order and time. Put a scope on them all to be sure. I have a sample pattern.

Could it be a shorted injector? I've had GM's with shorted injectors and it caused it so none would work. Been awhile since I've seen that though and not sure if it would only cause the one's you listed. Just throwing something out there.

real quick here. check injector impulse as well as spark. if you have both check for plugged injectors. this car could be in limp. it's rare but I've seen them not have a check engine light on. look at live data and see if the values are roaming. a quick note, i had one that was kicking my butt and found that the relief valve on the oil pump was frozen and the pressure was pumping the lifters up and floating the valves. any history on this vehicle would be helpful.........................................

fixed #6 injector shorted

wfo44 wrote:fixed #6 injector shorted

I'll PM you the address you can send my check to.

WHOA, what's this? a fix posted without being prompted? congratulations for the fix and thanks for the posting of the repair. it's unusual