3X Ref High Wire

[Redog]

OK the purple wire on the ICM plug on the driver's side was spliced into for the remote start a while ago. The remote start was turning the car off while driving. This was about 9 years ago.

Now driving the car above 2000 RPM is misfires, pretty bad too. Not all the time though.

I swapped in a brand new ICM, but still have the old coil on there. Car fires right up with practally no cranking at all. I have new coils but I'm getting them on Saturday with the rest of my stuff. When I can find them, they'll go in too.

I do have a SES light showing a random misfire (P0300) but it goes out a lot and comes back on (It's been off now for 2 days, but I'm been keeping it under 2000 RPMs.

Does this sound like the wire that was repaired with a souderless splice is working itself loose?

Plugs about 15,000 miles
wires about 10,000 miles
ICM about 500 miles
Coils about 117,500 miles (will be replaced soon but look like they are in good shape)

[Monza]

The purple wire on the ICM that goes to the crankshaft position sensor? (It does on my car anyway.) That would allow the remote start to cause all kinds of problems with the ignition.

[clutch1]

Another wonderful use for an oscilloscope...

If you can, get one ^^^^ and backprobe the purple and yellow wires and run the car. Look at the wave pattern, should be uniform, 5 regular spikes and a double kick. Rev it up... does it stay good or get messed up? That would be how to check that the right way. However, I have a sneaky hunch that it wouldn't get messed up.

Coils is a good start.. have you checked the coils max output? If the spark they put out isn't strong enough you could get misfire above certain rpms.

Another HUGE player.. do you have fuel pressure and volume?!?!? Get a fuel gauge.. should be 41-47 psi when it primes. Then, run it. Get a fuel gauge that lets you divert fuel, and with the car running, press the button and divert fuel into a graduated container (paint mixing cup is perfect). Let it flow for 15 seconds, and you *should* get 12-15 oz of volume. Any lower than that and you have fuel delivery issues.

How are the injectors? They might provide enough at idle, but not 2000rpm. A telltale would be fuel trim numbers... rev it up and look at the STFT, if it increased fuel delivery quite a bit, and you have pressure and volume from the pump, the injectors may be dirty.

Good luck.