Jfrahm

Anything is possible, but the IAC is a rotary valve so unless it is stuck open (causing a high idle) I do not think it would blow open with boost.

Black51

So once you've checked everything mechanical, it might be time to look at the DME. It would be nice if you could swap it out with a known working one to see what happens.

TurboTommy

I wouldn't think it would be a stuck open injector.
More along the lines of one or more injectors not firing properly.
If it's intermitent (changes in engine load, etc.) this not something you would necessarily see on the plugs, or hear under the hood at idle.
Make sure that the connectors are plugged into the injectors properly, put a meter on the wires; or better yet, swap out the injectors and/or the DME (like already mentioned).

Tom M'Guinn

How did you check the plug wires? On my old turbo rx7, I had a hesitation on boost for a while that no one could figure out. It turned out to be the plug wires, which were only 2 years old.

I also had a bad KLR that would cut ignition under heavy boost on my 951. I'm told there is a capacitor inside that can fail and cause ignition cut out when over saturated. I ended up getting a rebuilt unit and it fixed my problem immediately.

Scott H

Get a spray bottle, turn the engine on and then turn all the ambient lighting down. Spray the wires and look for tiny arcing, also works on some coil packs. If it is internal breaking you need a time domain reflectometer or you can try manipulating the wire while connected to a multimeter and look/listen for the continuity to drop out. Electricity is a pain in the ***.

mikey_audiogeek

Has anyone suggested ignition coil?

Easy to damage a coil when running high boost and wide spark plug gaps. A damaged coil would give the symptoms you describe. Plug gaps should drop 1 thou per additional 1-2lb of boost.

The impedance across the plug increases with boost pressure, which increases the voltage across the coil. This can damage the coil due to insulation breakdown or overheating. The coil driver circuit from the ECU can also be damaged.

http://www.aa1car.com/library/ignition_coils.htm

We ran 12 thou gaps on our Nissan race car, 36lb boost.

Subaru fanboys damage coil packs allllllllll the time. Plug gap, b1tches!

Cheers,
Mike

TheDice951

well, being that i replaced my plugs with new ones today with factory gap(wider than i have been running) it seems a lot worse..... i will close the gaps tomorrow and look into a coil...

JFreeman

pretty sure someone suggested the coil a week ago.........

TheDice951

Sorry man, I didn't think it would be the coil either until I put the new plugs in. It now makes much more sense to me... We will see what it does...

JFreeman

Don't stress I'm just giving you a hard time. There were so many suggestions on here that you never could have checked up on all of them. I hope the coil works for ya. Good luck.

Jfrahm

Yes you can't just check for spark, you have to see if the spark can jump a 1cm gap in atmosphere. Even more for a high boost engine. Think of the the compressed air like wrappings of tape around the spark plug terminals. The more air, the more insulation is added.

Bri Bro

Ignition spark tester. Low cost an better then holding a spark plug wire and getting zapped.

http://www.autozone.com/autozone/acc...ntifier=900800

TheDice951

a friend (mike carter) is sending me his spare, overnight, to me so i can replace mine... thanks mike!!

we will see tomorrow if it does the trick..... i will also gap the plugs a bit smaller... i run 18lbs at most so what should i have the gap at?

i am hoping this works... i want to have fun this weekend!!! im going on the PCA anual wine tour with the hurricane region..... it should be fun

TheDice951

THE COIL!!!! replaced it and made the gaps smaller, .030, on my new plugs.... runs nice!!!

m carter

Sweet!!! Glad it runs good now!! Great thread!!