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[tmsmini]

I am having my MPi engine rebuilt and the engine builder has told me that it was running very rich as the carbon buildup is very bad. The last time I reviewed the diagnostic outputs on an ACR4, the sensors all appeared within range.

If the O2 sensor was bad would that cause a rich condition? Is there another sensor that could cause this? Obvioulsy there is no way to control the mixture, so something must be causing it to run rich. I replaced the temp sensor awhile back and have also replaced the O2 sensor about 20K miles ago. The engine has 55K total miles on it but has been rebuilt previoulsy after 40k miles.

A thrust washer disintegrated and caused this rebuild after only 15K miles.

I will have to wait until I have the engine back and installed to really troubleshoot, but anyone have suggestions?

[DaveRob]

The CTS and the Lambda are most likly culprits...... CTS values can be read from the ACR but the Lambda shows a varying voltage so are you sure it is responding fast enough.... the 2 sensors causing rich run are usually Coolant temp sensor or Lambda. Their is a way of fooling the ECU around the CTS sensor but Lambda is a bit more difficult.... to confirm either is a pain and to replace Lambda is expensive and a chew on.

Just my thoughts

DaveRob