Drove home Wed with no problems, parked, on Thurs morning Cranks, no spark after coil. Switched coil from working 91-no diff. Ground tested fine on coil to body. 42psi at fuel rail while cranking. Recent new battery charged 100%.
I bought 92 Purple Camaro from 2 thirdgen members from Houston (Scott_92RS and 1bad91Z) about two years ago. 406 Stealth Ram +700R4 and 7730ECM put together about 10+ yrs ago.


Getting 12 volts before coil (pink). Tach diagnostic (white) connected and disconnected-no diff. Other 2 wires from coil to distributor removed and both had continuity to distributor. Has new Pertronix HEI distributor within last few 1000 miles when changed cam. Switched Ignition module from previous Dist-no diff. Low Ohm test on pickup coil wires.
Other 4 wires from Distributor A,B,C,D:
A-blk/red-continuity to 7730 ECM
B-Set timing connector-connect or disconnect- no diff
C-ppl/wht-continuity to ECM
D-white-appears ECM control signal of ignition module above 400 rpm didn't test since should not effect start up.


Did I miss something or assume something wrong? ECM bad? Way to test ECM with Multimeter?


I believe not related to this problem, but changed oil pressure sender/switch on block above oil filter (Tues) because puked 2 qts oil on exhaust on Mon.


Any help or point in a direction what to test next would be appreciated.
Thanks
Mark

 

Are you getting fuel injector pulse? I'd suspect the distributor pick up.

 

I didn't actually test injectors yet. Can these be tested with multimeter or is special tool required?
What is the best way to test pickup coil?
Thanks!

 

A device called a noid light is used test the injector harness. They're typically rentable at parts stores.

 

Okay, I tested the pickup coil more specifically and with both leads connected, ohm reading 978 ohms which is in spec between 500 and 1500 ohms. Also, tested each lead to ground and neither had short.
Everything seems to point to ECM problem.

 

Okay, I'm at a loss what to check next. The ECM seems to check out, jumper A & B terminals only show code 12 over and over. Does this actually confirm that the ECM is good and working correctly?
Also, since I have fuel pressure the ECM has to be triggering the fuel pump.


Wiring Diagram seems to show that the reference pulse comes directly from the ECM to Coil to Distributor to spark plug.
Is there a sensor that I'm overlooking that would prevent the trigger pulse side of the coil from the ECM?

 

Did you check the rotor and cap?

 

yes, the whole distributor was purchased a little over a year ago with new cam change. The rotor does turn with engine cranks. I don't have any spark out of coil with 12 volts into coil from ignition but no pulses to the other side of coil. I switched coil and ignition module with known working ones. I tested pickup coil with multimeter and no shorts and tested within ohm range. I have continuity on pulse wires from ECM to distributor. The ECM seems to check out with no codes stored. I don't have a spare 7730 ECM to swap to check but may have to find one. Local picknpull yards only seem to have few cars that might match.
Thanks for responding.

 

I just went through the same thing. I just replaced the ignition control module and it runs again. Only had about an hour of run time on the one i replaced. Hope it isn't a continuous problem. By the way did you by the car up in tomball. If so i almost bought it. Car sounds nasty.

 

Wow I am literally having the same exact problem to a t in my 91z. Replaced both the rotor coil and cap and I'm getting 9volts to the coil but nothing out. My car ran fine last week. Maybe a wire got knocked loose or I heard it could be the ignition control modual. Good luck and lemme know on any updates please

 

Apparently if the ICM goes bad there is no spark generated by the coil. I guess it tells the coil that the engine is running.

 

I swapped out both distributor and ECM from local picknpull this weekend but still no spark. I believe at least one of the ICM are good out of 3 but may have to get tested at parts store to confirm. I checked all fuses again with key on and off and all good and have power when should. I probed most wires into ECM and two orange wires from battery have power and ignition wire has power with key on. Grounds check out.
Does ECM have anything to do with initial startup? Or only after above 400 rpms?

Yes, I did buy car from Thirdgen members around Tomball, TX.

 

I don't recall if the ecm has anything to do with spark other than adjust timing. I guess in theory it could fail and stop spark. Check with Tunedperformance or RBob to get an answer if it has anything to do with initial spark or not. Bad PROM maybe?