I have searched through the archives and am even more confused than when I started. Here are the symptoms my car is giving me. My car will start up and run fine. Then at what seems to be a random occurence, it will start bucking and stumbling(that is physically what the car does, the tach will starts to jump all over the place in about 1500rpm increments, the car seems to pulse and then miss about 4 cylinders. The SES light flashes with each pulse and then the car dies. The car won't start after that. If I let it sit for about an hour and come back, the damn thing will crank right up and then do the same thing about twenty minutes later. Only the first time seems to be random. Here is what I have done. I checked all of the plug wires for burns, the harness connections for secureness and all of the vacuum hoses for leaks. Everything looks good. I removed the smog equipment from my car and I had to remove the DFI and go back to the stock ECM until I get an MSD distributor. I noticed before hand a ticking sound coming from under the dash. It increased with RPM's and is only there when the engine is under load. I can't hear it when I am under the hood, so it isn't an engine noise. I don't know what to look/listen for now. Any suggestions? Thanks for your help.

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1989 GTA TRANS AM
Was a TPI 305 & t-5 car.
Is now 383 stroker w/ the same T-5
World products Sportsman II heads(64cc fast burns). Lunati pistons@10.5:1 and 452/462/112* camshaft. Eagle crank and 6 inch rods. Ported/polished/port matched stock TPI intake. T-5 on a suicide mission.

 

Pickup coil would be my first guess, module second.

The light flashing with the miss, indicates the ECM is not seeing an ignition pulse.

The misfiring of the iginition has probably acred the heck out of your cap as well, may as well pick up a new cap and rotor too (not that this will cure it.

 

Mike has a good probability. I'll toss in a possible cracked reluctor as a third option, and a failing ignition coil after that.

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Later,
Vader
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"Fear is how I fall, Confusing what is real..."
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The coil is brand new. I don't know how it would have failed this early on. How would I test and or look for these things? I am going to replace the distributor since I was getting a new MSD for the DFI anyway. Any other ideas? If the O2 sensor was shot it would run bad from startup right? I have only been running rich for the past two days with the stock ECM. Would that be enough time to kill the O2?

Thanks for the advice. I am learning a lot with the engine swap and trying to work out all of the bugs. Bite off more than you can chew and then rely on those with more knowledge to show you the way through your ambition. I am sure someone smarter and older than I has said that before, I just don't know who.

Robert

 

A dead oxygen sensor wouldn't affect the operation until after the engine warmed a bit and the ECM expected an input from the sensor.

The pickup coil can be tested with an ohmmeter. You should be able to read about 500-1500 ohms across the coil, and nothing to ground with the coil leads disconnected from the vehicle wiring.

The HEI module is very difficult to diagnose without a test bench or specialized equipment to emulate operating conditions. You can remove teh module and have it tested at many auto parts stores for no charge.

Your replacement distributor should eliminate both of those possibilities as well as the cracked reluctor theory, as remote a possibility that might be.

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Later,
Vader
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"Fear is how I fall, Confusing what is real..."
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