High Positive Fuel Trims. - Mazda 6 Forums : Mazda 6 Forum / Mazda Atenza Forum
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post #1 of 1 (permalink) Old 03-22-2015, 10:55 PM Thread Starter
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High Positive Fuel Trims.

High Positive Fuel Trim, Lean Warning

The car is running 20+ % positive fuel trim. The MAF is reading high 3 gps at idle (Grams per Second) and it runs fine with fuel trims around +5 to +7. From what I have read, a gps per liter is reasonable. This makes the reading good. But, if it should be higher at idle, please let me know. Also, the one from my 8 reads the same numbers. At higher speed, the trim rises to +22 or greater. Occasionally triggering a P0171 (lean bank 1) or P0174 (lean bank 2) error. Car does not throw CEL, but is darned close. It did when the intake tube cracked at about +22 trim.

Possible Failures:
MAF, unlikely, a very simple device, and the one from the 8 reads the same.
Vacuum Leak, would have to be massive. Should be able to hear it, and it would affect idle, I plugged all the holes on the intake manifold and it did not help. Might want to do it again at high RPM. I was looking for a low RPM leak.
Bad 02 sensors. All I have read says they will increase emissions and reduce economy. Sounds about right for running rich.
Fuel Pump, stats to run out of steam at higher loads?

What else?
04Red is offline  
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