OK, so I have a 383 L31 TPI T56 in an '88 T/A. It previously ran great on the stock ECM with a chip, though it had it's share of driveability problems which led to the swap in the first place. Now after replacing the harness and having the 0411 tuned, it will not run. I get fuel pump prime, even fuel smell and injector pulse while cranking, but no spark. I have:
-verified circuit integrity. All check out ok on the ign circuit.
-verified pinouts according to 02 Express 5.7L schematics. All ok.
-had PCM tuned. When PCM was suspected, replaced PCM again with another tuned PCM. Still no spark
-replaced CMP sensor. No change.
-verified CKP sensor is tight against the reluctor. No excessive gaps. The crank reluctor just barely kissed the tone ring, then was shimmed away .015"
-verified with the tuner both PCM's were VATS disabled
-verified injector pulse while cranking
Problem is I still have no output to the ICM from the PCM. I have CMP and CKP input, but no output. When I used a stock PCM from a 4.3L truck, to verify the circuits before sending in the second PCM, I fired the engine on the stock PCM. It ran (horribly) but it was enough to verify it worked.
Any ideas? I'm hoping to find a way to test the ckp sensor to make sure it's sending a clean and strong signal to the PCM, but with fuel injector pulse, I doubt that's the problem...