I thought my car was cured with an ECU reset but the warm misfire came back. Now it barely idles, and random misfires all the time once it's warm... Recently put new cam and crank sensors in it just to see and it still does it.. My only thought is the knock sensor is for an EJ25 because I used the EJ25D wiring harness. Otherwise, I'm thinking it could be the ICM/ Ignitor going thermal because it seems like the ignition drops off but the fuel keeps pumping.. Starts doing this when it's up to temp. Cold it runs and drives fine, and it does run ok down the road... Is an ICM worth trying? I have had it on my scanner and everything looks good on live data, just starts missfiring

OEM plug wires?

 

Fancy plugs?

NGK plug wires, and OEM spec NGK plugs

Folks have reported NGK plug wires to be o.k.  I still go EOM myself.

 

Ignitors very rarely fail - infact I stopped pulling them when I'd part cars.  I should have a few if you need one though.

 

Coil pack status?  Try the spray bottle test?  Often when they fail due to heat the crask opens up and the water bottle spray test can help confirm.

I would clean the maf and change the coolant temp sensor and see what happens.

so it runs fine when cold, at first start, but misses when it warms up.

 

how about the temp sensor?

 

runs fine in open loop, but misses in closed loop.

 

how about the o2 sensor?

Edited July 10, 201312 yr by johnceggleston

My scanner shows the temp at 199* when this happens and that is the coolant temp reading with my IR thermometer. I can buy one to be sure, but I don't think that is it.. Coil was new from Standard Motor Products.. I'll clean the MAF and see.. Original 2.5 missed on 2 cylinders when warm and I originally thought it was injesting that much coolant but I think it might be related. That was my thinking with the ignitor

Edited July 10, 201312 yr by matt167

Try MAF unplugged?

 

Remember 2 coolant sensors.  One for ECU, one for dash - IIR the dash is the simple spade under #3 intake.

 

I believe those are CRAP coil packs.  I had trouble with those so then I went to used Diamond coils - and I have atelast one of those left too.  Remember coil pack off a lot of 2.2's works too if you happen to have any.

 

Heck if a member lived close you could swap parts and see which parts the problem followed.

 

Remember - when nothing makes sense look for the stupid simple stuff!  And go back to scratch and start all over again diagnosing.

 

Good luck.

I know about the 2 Coolant sensors, but my scanner reads the ECU.. MAF unplugged does the same thing except the AT temp light flashes? and it puts on the CEL didn't make sense I used a 2.2L coil, just swapped the connector to the 25D harness. The 2.2 coil that came with the engine had a rubbed wire and looked bad, which is why I just opted to replace

Wow - I'm not much of an electrical guy but I'd be afraid to replace the coil connector.  And I'd think that could be th eproblem as it heats up.

 

What cylinders misfire?

 

Same side or opposing sides?

I've had codes for 1, 2 3, and 4 but only 4 once or twice.. Coil connector would be the last of my worries. I stripped the wires, soldered them and then used shrink tubing. If anything the solder would act as a heat sink keeping the wires cooler.

How's the o2 sensor reading? Maybe it's a faulty front o2 sensor

Disconnected the front O2 sensor to run it in open loop.and it still does it.. O2 readings are within spec

Double check the timing belt. Drivers cam could be a tooth off.

I have spare Diamond coils if you need one.