Crowhater

I will change the coil but it is brand new also.



On some of my high HP stuff our distributer caps are vented so you do not get cross fire from electrons. Have any of you guys delt with this issue on the C4? To me the stock HEI should be more then happy until 6000 rpm or better.


I want to go to the track this Friday, I have also found a new set of 275/40/17 MT ET street for 400 dollars, but I do not want to buy the tires until I know what the deal is with the car.

engle1147

Did you change to a "new" HEI coil before or after you had the super heating problem with your distributor cap?

If you look under the body of the distributor (down by the pick-up coil area) you'll see that the distibutor is "vented" down there.

I'd check the spark plug wires for "shorts" and pull all the plugs (to inspect/gauge them) again before you swap in a "new" coil.

Crowhater

The coil was new before last weekend when the dist got hot and we lost spark. When it all cooled down it started back up. I had the Module tested and it was good but I changed it anyway. Also when it started missing Friday night I ran a wire from the - on the battery to one of the screws that holds the coil down to make darn sure it had a good ground and it still sputter down the track.


For the record it does not matter if the car is hot or cold it will do this just the same. It also comes and goes for no reason. Right after that last video was taken I said screw it and drove home . ( 30 ) miles. About a block from the house I staged the car then launched it and it ran perfect. GRIMLINS

Oklahoma_mike

Crowhater

GUYS I AGREE! I dont know what it is!!! I have changed everything and it still comes and goes. This is keeping me awake at night, I don't care about turning the wrenches to fix it but I am out of ideas.

Oklahoma_mike

I am guessing you cooked the HEI. Might try checking the bearings on the HEI make sure the drive shaft for it turns free and true. I would tear it apart and inspect eveything or replace it if you have the coin. just my 2cts

Midnight 85

I think I would pull the HEI and go over it with a fine tooth comb. Check for up & down excessive play, etc. I'm about 99% sure that is an electrical gremlin. After you check the HEI then go looking for loose connectors that are moving under hard acceleration.

Crowhater

I have had the dist out and it looked good, I have also looked at the wear line on the points in the dist cap and they look good. Saturday I took everything apart again and made sure the connectors for the module where tight and that I had good grease under the new module. I took the cover off the ECM for the chip and put some foam under the lid to make sure the chip was not moving. Then I took it down the street stone cold and launched it. The car did the same as the video. Right now my friend has the car and he is swapping stuff from his car to mine to check it that way. He swapped out the TPS and the problem went away, then he put mine back on and the problem is still gone. Nothing shows up on code scans and there is not spike or drop in fuel pressure.

Midnight 85

I'm sure you checked this but is the little spring in place that keeps the pressure on the center of the rotor? I'm going to venture to say that it is something very simple that has been overlooked.

Crowhater

My friend has been data logging the problem and when the miss happens the engine goes rich according to the O2 sensor, so it has to be ignition. He is going to try to change out the factory coil for a performance coil and see what that does.

BevoVette

Do you have a revimiter on the HEI and is it set right? It sounds like a rev limiter actuating.

Good Luck :>)

Crowhater

It is the factory HEI dist

pr0zac

what plugs are you running? what are they gapped at? have you checked them lately?

Crowhater

Spark plugs are brand new they are for this motor

pr0zac

is your timing set right?

Crowhater

It is set at 4*

ddahlgren

Define goes rich how rich? The stock O2 sensor is pretty useless for values other than 14.7 / 1 AF It was never designed or intended to read anything else. It might give some clues rich or lean but generally how much rich or lean is a crapshoot. An ignition failure will most often read lean not rich as the excess air from the dead cylinder will make it look lean. An O2 sensor only reads combustion by products not raw unburned fuel. I have found most intermittent problems are electrical mechanical things do not heal themselves very often. I doubt if GM designed the electrical systems in these cars to last over 20 years more like 7 to 10 maybe they are not made to be the last car you buy that will run for the rest of your life if that makes any sense. If I had to make educated guesses on places to look at it would start with all the ignition secondary wiring and parts. None of them will throw a code as they are outside of the ECM. The other thing that makes me think ignition is it only the worst under a high load. A bad tps or other sensor really does not know much about load. what does the tach do when this happens? The tach if stock is on the ignition secondary so something as simple as a tach filter can cause a skip if shorted. Either not mentioned or I missed is if this is a custom tune or a stock chip. The most useful thing would be a datalog of a good launch overlaid on a bad launch if it is in any way a sensor it should show up there.
Dave

pr0zac

i thought it was suppose to be at 6?

Crowhater

I changed the coil again and the problem is the same. I am at a loss, I guess I will spend the night reading the service manual again.

Midnight 85

I'm not sure if this would be a factor but what about the grounds on the DRIVER'S side of the engine? That side lifts under acceleration, maybe a loose or partially frayed ground??