I recently swapped a 1994 LT1 into my '71 Camaro. Now the engine will crank but not start. I have read over the many thread that deal with this topic and tried everything I could find. I do have 42 pounds of fuel pressure at the rail but no spark and no signal at the injectors to fire. The optispark, coil and ICM are new.

The wiring and computer were modified by Jeff Roberts in New York who now I have found out is far from the best and his customer service is terrible.

I did the optispark test that is stickied and I have the proper voltage at the ICM connector. I tried seeing if there were trouble codes present but through the several times I tried it I received, "Vehicle not responding."

Does anyone have any suggestions or ideas? Please, I am really desperate.

Thanks everyone and especially shbox who has been very helpful.

 

what brand of code reader are you using? i had the same error message with an innova and when i called tech support they gave me other vin codes for the same model year that allowed it to read my pcm.

 

It is an AutoXRay EZ-Read 2000.

 

is the cigarette lighter operational? if the circuit is blown the pcm may not be readable.

 

I built a new dash for the '71 and it does not include a cigarette lighter. All the fuses are good though.

 

is the pcm sending signal to the icm/coil?

 

It was getting the proper voltage to the ICM.

I made the decision today to send my harness and computer to Speartech because there was a lot of bad workmanship done by Jeff Roberts to my original harness. I have been chasing the problems using all the fault isolation diagrams on Street & Performance.

Speartech will troubleshoot both the harness and computer then John will get back to me with what he found.

Thanks!

 

ok...hope it all works out

 

did you ever figure out what was wrong?

 

Well, I got my Speartech harness back last weekend and installed it. I tried to fire the LT1 up today and it still cranks but will not fire. There are a few times where is gets really close to sounding and feeling like it will fire but to no avail.

I am getting a trouble code now which is different from before. The code that comes up is 41, Ignition Control (IC) circuit (open circuit). I cannot seem to find anywhere what that really means. Optispark possibly? Does anyone know?

Thanks!!!

 

Make sure the coil is getting +12V from the ignition fuse, and that the connection from the coil to pin "A" on the ICM is providing 12V to the ICM. The IC Module pulls power off that connection. DTC 41 will set if you don't have power to the IC Module. When DTC 41 sets, the PCM disables the injectors.

Make sure yoiu have a good ground to pin "C" (black wire) on the ICM. With a voltmeter on pin "B" (white wire) you should have near "0" voltage with key one/engine off, and between 1 and 4 volts with the engine cranking. Ignition off, put a test light across pins "B" and "C", light should light up. Ignition "on" put the test light across "D" and ground, and across "A" and ground. Light should be on.

The possible causes of the problem are:
-short on the white wire from the PCM
-open on the white wire from the PCM
-faulty PCM
-open circuit between ICM and coil
-open ICM ground
-faulty 12V circuit to the coil
-faulty ICM

I think that's from a 93 diagnostic chart. Not sure if its exactly the same for the 94.

 

With a little bit more testing since my last post I have discovered that I do have spark and and an injector pulse. The thing about getting the code 41 that was odd was it showed up in my history codes section and not my current codes. The only thing is today was the only day I have been ever able to pull off a successful scan, before with the old hack job harness by Jeff Roberts I was never able to pull codes, all I got was "Vehicle Not Responding".

 

Sounds like he didn't have the ALDL harness wired correctly.

 

Most likely, not to mention Roberts put a OBD II connector on a OBD I system.

In contrast Speartech has a very nice harness and he does a nice job of going through it.

Right now I am a little suspicious of the injectors not functioning as if they were clogged. The engine that they were originally from sat for a long time full of water before I bought it and rebuilt it.

 

He's in good company. So did GM in the 95 F-Bodys.