My z6 sucks! (crazy issues, misfiring, etc..)
 

Alright, it's a 99 EX Coupe with OBD2B wiring harness, running an OBD1 z6 motor (p28 ecu and conversion harness).

My situation for the last couple months has been that the motor misses during acceleration around the 3500rpm mark. It also misses a tad at idle.

No CEL.

It does run fairly smooth up to 3500rpms. In order for it to run like that, I have to have the dizzy almost all the way retarded, which usualy means the cam timing is off...however...

..The motor is mechanically timed. I set the motor to TDC and took the crank pulley, timing cover, etc off.The mark on the Crank Gear was inline with the arrow on the oil pump, and the line on the cam gear was in line with the plastic pointer (7oclock position).

So, I thought it was a bad remanufactured dizzy...

Got a new dizzy from Distributor King, tossed it on, fired it up, and it popped and misfired like crazy. No matter where the dizzy sat, it misfired and ran like ****. So I tossed the remanufactured dizzy back on thinking it would go back to the way it was, but it didn't. Still misfiring and running like crap.


I'm at a complete loss. I need to have this thing running ASAP. If anyone has any ideas, post up, all help is appreciated.

Thanks,

Tony

RE: My z6 sucks! (crazy issues, misfiring, etc..)
 

My first thought would be that the pulses from the distributor are getting corrupted on the way to the ECU, maybe a bad ground or something in the conversion harness. I think they're supposed to be shielded cable throughout. If the shields on the cable are grounded or touching each other where they shouldn't that's a "ground loop" and an opportunity to pick up noise.

RE: My z6 sucks! (crazy issues, misfiring, etc..)
 

BUMP anyone?

RE: My z6 sucks! (crazy issues, misfiring, etc..)
 

For wierd problems like that, you are probably going to need a scope. I would check the waveforms for signal wire to the coil. I would also check the waveform for the crank sensor. Also check wiring like mk378 said.

RE: My z6 sucks! (crazy issues, misfiring, etc..)
 

Okay, I'm a complete idiot and I ****ed up the firing order..

New dizzy is on now, and the car rips up to redline without misfire. Still misses a tad at idle and when i initially get into a gear at low RPM's, but I suspect thats due to the following reasons..

-Possible fouled plug or two from all the misfiring lately
-Timing not set perfectly because I don't have a light and did it by ear
-Something else (any ideas?)