Syvecs Forums

Morning All,

I've recently bought an MR2 with a S6 ECU and it seems to be having misfiring issues. It has the 1zz-fe COP system, and I have checked the resistance of the coils, and the condition of the plugs. The coils all read between 12-17 kOhms when warm.

The misfire only happens when the engine has significantly warmed up, which is what made me think a coil is breaking down, but when I was looking for errors on the ECU (there are none), I noticed that the ECU runs in a cold 'limp' mode. That made me think, could it be possible that the problem only occurs when the ECU comes out of limp mode?

So, if I use the data logging feature, will that capture any useful data for troubleshooting a misfire? Also, is there a maximum length of cable that the tx/rx pair can be to connect a laptop? I'd like to extend the wire into the cabin, but it doesn't pick up the ECU when I do.

Here is some more info about what I've observed/tried:

1. I have pulled each coil in turn when the engine is missing, and each coil makes the car miss noticably more, so I don't believe it is complete coilpack failure
2. When the problem first arose, the car missed at low revs, but cleared it's throat, then drove properly, but kicked out lots of black smoke for a few seconds
3. The wideband readings are very erratic, and it seems to go very lean when the misfire is at its' worst
4. The rev counter has stopped working (speedo is fine, and the ECU has an RPM input, so probably not related)
5. Spark plugs are new (less than 100 miles)

Is there anything else I can do before I have to call the professionals?

It's possible you're experiencing a limp/trip limiter. Check to see what the limp mode rev limit is set to and then see if that coincides with your breakup. Lower the limp limiter to see if the breakup follows. If you determine it is a limp limiter, view and/or log the sensors that have limp trips enabled to see which one is causing the issue.

Sorry, I didn't get notified of your response. Subscribed to the thread now...

The only error that is showing on the ECU is the MAP sensor out of range error. I clear the error, but it comes back the next time I start the engine.

Is the MAP sensor likely to be a rebranded GM sensor (they look the same)?

Any clues as to where the limp limiter setting 'lives'?

Did you ever get this sorted?

It seems that my fuel pressure regulator had worked loose. I upped the pressure, and the misfire has gone