L69 and LG4 ECM Compatability?
 

I've had an ignition problem on my 83 L69 5 speed for a while now. Every once in a while, it will randomly cut out like the key is being turned off and on rapidly. The cutting out continuously changes in frequency like morse code. The only visual indication I see is the tach drops suddenly towards zero RPM in sync with the ignition cutouts.

I've changed out the module and the pickup coil, (reluctor?). I connected a test light to the distributor power connection and ran it into the interior to see if it was a power problem. I've even disconnected the tach lead to eliminate the possibility that it was grounding out somehow. I didn't change out the coil as I have yet to solve any ignition problem in the past by doing this. I'm afraid that the computer might be at fault. I don't know what else to do.

Anyway, I might be able to get an ECM from an 84 LG4 5 speed from a T/A. Besides the difference in the chip, would this work as a troubleshooting aid or even a permanent fix if this solves the problem?

If it's not my chip causing the problem, can it be swapped to the new ECM so I can keep the same L69 fuel and timing profiles?

Thanks for any help someone could provide!

Larry

Re: L69 and LG4 ECM Compatability?
 

Don't see how the computer could be causing an ignition problem. You can disconnect the computer from the dist and it will still run. The computer only controls timing advance and the ICM contains a rudimentary timing advancement that will allow it to run in limp home mode if the ECM fails. Try it. Disconnect the four wire connector, just like when you set the timing.

On the swap, your 83 L69 should have a KS. The 84 LG4 won't. I'd assume from this that they are incompatible. Anyway, look towards ignition problems.

Re: L69 and LG4 ECM Compatability?
 

I guess the only thing left to change would be the coil. If I can get a complete distributor, I'd like to try that too. At least it might help isolate the problem.

Could you explain your last statement about the term KS?

Re: L69 and LG4 ECM Compatability?
 

Knock Sensor.