Mechanics

MISFIRE ABOVE 3200 RPM

2003 Ford Ranger

Engine Performance problem
2003 Ford Ranger 6 cyl Two Wheel Drive Automatic 108000 miles

NO obd 2 codes, runs great till warm up (closed loop), then misfires up hill, under load or just revving engine. Have new coil pack, wires, plugs. Fuel pressure is 61 psi (normal). With master obd 2 computer, shows mixture stays lean above 3200 rpm (no computer correction). Replaced the front two oxygen sensors but not the back two. Also intermittent rough idle. Any Ideas?
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Blondebeard
April 8, 2008.



Most likely the Mass Airflow Meter is out of range. They dont always set a code, but will do exactly what you describe. You can try a special cleaner for them, but I personally havent had any luck with that fix lasting. Always use an OEM part (Ford)

Tiny
Jack42
Apr 9, 2008.
Ok thank you, I will replace it and keep you posted on what happens.

Tiny
Blondebeard
Apr 9, 2008.
Well, put in new mass airflow meter and now the idle is perfect (was running rough also) but still misfires above 3200 rpm. By the way, its a small band of misfire, above 4000 rpm, misfire stops.

Tiny
Blondebeard
Apr 11, 2008.