Engine cuts out at 6000 RPMs

[Tubby]

It's been a great source just by searching. People all seem to be nice and not snippy.

Next step is to replace the ignition switch. We bypassed the kill switch and it still cut out so we don't think that is contributing.

Don't quit...

[Tubby]

Update:
Cutout continued to get worse and we turned our race into a fix it session disconnecting electrical items that might be causing the cut out. Car handled like a dream and the cut out issue was extremely frustrating.

We threw a belt and overheated the motor. Weekend done.

Taking the motor apart we've got a hole through the #1 cylinder in the head created by the overheating. Head is now junk.

Our machinist pointed out that the pistons were hitting the head on at least two cylinders and that might have been causing the issue.

The bottom end is okay but we are reringing the pistons and rebuilding the head. We are also doing our spare motor from the parts car which was in very good shape. We'll through the new motor in and we'll see what's going on now.

Thanks all for the insight.

[Subsqu125]

Hey Tubby, did you ever figure this out and resolve the issue? My teams car is having the same problem and were are looking for some insight. Thanks

[Tubby]

We think it was the pistons hitting the previous head. We also had the fuel pump go out last race.

New rebuild runs with no issues so nothing electrical or sensor related.

[Tubby]

Update: The mystery cutout started to occur with more regularity. It's doing it now with the fresh rebuild. We've swapped out three engine harnesses, 4 DMEs, almost everything electrical. It doesn't happen every time to its a b!tch to troubleshoot. Never does it while idling or sitting revving, only driving.

Got fed up and decided to either ghost it into a lake or take it to a shop that still works on e30s. Now it does it everytime so should be easier to find. Took the shop about two hours to find it.

A loose piece of metal was migrating around inside the idle control valve. It would short that solenoid to ground robbing all power to the DME which then would think the car was shut off hence the cut out. They found it by hooking up their scope and taking the car for a spin. It started doing it everytime as the chunk finally wedged itself in place. Replaced the idle control valve. Fixed!

By the way, that was just about the only thing we didn't replace. Who would think an idle control valve would cause a high RPM cutout.

We've raced the car now for several races with no cutouts on two different motors.