[cmexlr8]

This is a 88 TC to a 92 stang swap. It runs and cranks. It breaks up when the rpms rise either driving or in nuetral. I set the timing with the spout connector unplugged. When I put the plug back in, the car still cranks and runs, but the timing stays where it was set with the connector our - for example 13 degrees. I can rev the engine with the timing light on and the mark never moves.

I have ohmed the wire with the connector plugged in and did continuity test from the distributor to the spout pin on the ecm and there are no open circuits.

Any ideas?

[Dr_EluSivE]

Have the Ignition Module Tested, Or swap a different one on.. I seem to remember hearing that a bad module could cause that

Dr.

[cmexlr8]

I had the TFI Module tested and it passed. He tested it three times in a row to make sure it was good and warm during the test.

I did notice that the second prong on where the wire connector plugs in had what appeared to be soot on it. I am going to check the plug to see if the socket is engaging the module all the way or is it loose.

[Dr_EluSivE]

You say its a TC swap, I would double check your wiring on your ignition harness, If i remember right that was the one that required the most repinning. Maybe you missed a wire? II will have to go back in my notes and see if there is anything that might have caused that.

Dr.

[cmexlr8]

Found the problem - dead or dying ECM. Before I got involved in the project, the air meter was hooked up with 12 volts on the signal return or one of the wires, not sure, but our theory is that the 12 volts killed the ecm. What puzzles me is how the car still ran?

We put a known good LA3 ecm in this morning and the car immediately acted different. The fuel pump actually primed and then shutoff - it had been just staying on. It fired on the first hit and ran at fast idle and then eventually bumped down. It now boosts fine without breaking up and the timing is advancing when its supposed too.

[Dr_EluSivE]

Originally Posted by cmexlr8

Found the problem - dead or dying ECM. Before I got involved in the project, the air meter was hooked up with 12 volts on the signal return or one of the wires, not sure, but our theory is that the 12 volts killed the ecm. What puzzles me is how the car still ran?

We put a known good LA3 ecm in this morning and the car immediately acted different. The fuel pump actually primed and then shutoff - it had been just staying on. It fired on the first hit and ran at fast idle and then eventually bumped down. It now boosts fine without breaking up and the timing is advancing when its supposed too.

Sweet, I had a similar experience where the ECM allowed the signal return path to float and I had a code for practically every sensor. The CEL was always on but the car ran fine. I could unplug almost all the sensors and it made no difference to the car. That was a pain to fix. Glad to see you got it all sorted out.

Dr.