Misfire from 4 to 6k

[Thomas L. Parker]

It would seem that our 93 M6 is running rough between 4000 and 6000 RPM. We replaced the opti-spark 1999 and have put about 50k miles in the car since then.

This problem has just started. There was no prior indication that anything was going wrong.

Has anyone else had a similar experience. If so, what did you find was the problem?

Thanks,

Tom

[Joe 1320]

I don't know if this will help, but a few years ago I was chasing a similar problem. I was getting a WOT misfire/knock retard with a brand new opti, coil and module. I wasn't getting any codes either. It turns out that the flat connector going to the driver module was making intermittant contact with the pins. It seemed to run great otherwise. I messaged the pins a little to make good contact and it fixed the problem. Hey, it's a shot.

[Flash 97 WS/6]

Also take a look at...

I would also be checking fuel pressure... since it is happening at the upper RPM range. Put a gauge on it and make sure you are not dropping fuel pressure in that range. Could be a fuel filter or pump going bad??