Help! Misfire Code 300

[Ryan96WS6]

My 96 M6 has been sitting for a couple of days. I only drove it today to take to a friends where we were to install a new waterpump. The service engine light came on and it was running terrible for a bit. Most obvious low RPM under load (like skip shift to 4th it could not handle). After about 5 min it started running better. Could now handle skip shift. Still felt like it could be running a little better tough to tell. (not enough time with the car) Got the diagnosis at Auto Zone. Code 300 multiple random misfire.
The question:
If it is the opti-spark would that have its own code?
Could it still be something else; plugs, wires, sensors?
Why has my 2 week old dream car turned into a Nightmare!
Thanks
Ryan

[Joe 1320]

When mine went, there was no code. Start troubleshooting the ignition system. Plugs, wires, opti, coil and driver module. Make sure all connections are good.

[Injuneer]

You mention replacing the water pump. Has it been leaking? On the Opti? Water leaking from the weep holes can be enough to drench the Opti and cause temporary or long term problems.

There are no codes for the Opti if it is a problem in the high voltage sesction - cap & rotor. Just a resultant "misfire" code. If there is a problem with the rear section of the Opti... the optical sensor, there will be codes set for problems with the high resolution and low resolution pulses that the Opti provides. If you didn't have any "Opti" codes, you didn't have a problem with the optical section.

If your pump was leaking, is it possible there was water on the coil or plug wires, on the terminals for these wires on the Opti, or on any other sensors in the front of the engine?

[Ryan96WS6]

Thank you guys,
I will start with just replacing the waterpump as planned. I am not 100% sure the coolant leak is from there, but it is in the area and others with the same problem (leaks on the belt and is projected on the underside of the hood) said it was the waterpump.The SES light is still on, as I said though the car is not missing like it was for the first few miles this morning. Maybe the fact that it sat for 3 days allowed moisture to reach some wires (I can only hope not the opti). I will still go ahead and put the waterpump in tonight (I think) and hopefully not have to pull it in a couple days to fix the opti.

How do I clear the SES light or will it turn off when it no longer senses a problem?

Ryan

[Joe 1320]

A scanner can clear the code, so will pulling the fuse to the PCM as will disconnecting the battery- just make sure your radio's theft loc isn't activated or the radio will be shut down until the code is punched in, or you'll have to pay the dealer to unlock it. No problems with just pulling the PCM fuse, only when disconnecting the battery.

[Ryan96WS6]

Thanks again,
That brings up another question though. My car didn't have an owners manual when I bought it, and I don't know the theftlock code. Is the only way to get the code by paying a dealership?
Ryan

[RangerBob]

Yes about $75