Hey everyone,
Here's my problem:
My ignition is cutting off around 3000 RPM. It USUALLY does this, but not always. When it does cut off, it cuts back on within 2 seconds or less. When it cuts off, the tach drops down (or flutters) and the check engine light comes on. The only trouble code present is a code 12, which is loss of ignition signal, the same as when there are no codes saved up. I thought the pickup coil was failing to send the reference signal to the modual. I changed it, but it did not fix the problem.
What do you all think could be wrong??
I don't think it's the ignition modual because they either work or don't work. The coil is an accel coil and is 5 months old. The engine is a 305 TBI (see sig).
Please help, this problem has been going on for a while now.
Thanks!

 

Truckman,

If the Accel coil is a low-resistance primary (as many of them are) you may have an incompatibility between the HEI module and require coil primary current. This extra load could be shunting the signal from the PU coil to the point where the ECM cannot detect it. An aftermarket HEI module is often necessary with a high-current ignition coil.

It is also possible that the reluctor has a crack that is being opened by centrifugal force. A missing reference pulse(s) could result.

 

Ok, can anyone recomend a good aftermarket ignition modual? How is the Flame Thrower? Or how about that MSD one?
Thanks Vader. I didn't see any cracks in the reluctor, so I don't THINK that's it, but we shall see.

 

Well, I tried putting my stock GM coil back on, but it still does the same thing!!! I changed my ignition module with another stock GM module (because my old one just fried), but of course that didn't help either.
This is really beginning to annoy me, does ANYONE have any new suggestions????? I'm begining to wonder if there is something wrong with the reluctor, like Vader suggested. Anyone ever have that happen?
Thanks

Edit: I have noticed that this only happens under heavy throttle. If I slowly run the motor up to 5K, this does not happen. But, under heavy throttle it happens just over 3k. This is crazy, please help!

 

It sounds as if your HEI is not getting enough current to fire at high RPM - is the heavy RED power lead and connector in good condition? Is there a solid 12 Volts with IGN on?

You should be able to run a high-current load like a headlight bulb or blower motor etc from the red power lead when the ignition is turned on if you want to check it.

Ensure that the engine block is properly grounded to the battery (-) terminal just in case something funny is going on there. It's not likely but worth looking at.

 

Truckman,
Is this happening while you are driving or just sitting there at any time , like in nuetral or park? I know it sounds really simple, but I had the same problem under acceleration at relatively higher RPMs, my car would shut out. After much confusion I found out it was something as simeple as the wires were too tight that plugged into distributor. Under heavy accel., the engine would torque enough so that it slightly pulled the wires loose. Sounds elementary, I know, but it worked for me.

Maybe it IS something more complicating, I dont know, just thought I'd throw that out there just so you knew.

 

Thanks for the replies. It does this when not in gear too, when I'm idling, but again only under heavy throttle. I changed the wires going from the coil to the ignition module, but I havn't checked the one powering the HEI. I'll check that out next.
Also, all the wires are long enough so that they won't be stressed when the engine torques.
Out of curiosity, could any other senors cause this, such as the MAP or TPS? Like I said, I'm assuming it's ignition, but I don't have solid proof.

 

My dad had the exact same problem on his full sized van. He had a mechanic look at it and he was getting a code that said it was the TPS. This guy knows his stuff, and said that therefor it was more than likely the TPS doing this, because that is one of the symptoms of a bad TPS. He replaced it, and needless to say, it wasnt it. Turned out it was a bare wire that was grounding out.
But yes, to answer your question, as far as I know, it could very possibly be the TPS.

 

I fixed it!!!!!

My ground strap at the back of my engine was broke. I fixed that and the problem went away compelety!!!!!!!
Thanks for the help everyone