Mechanics

MASS AIR FLOW SENSOR

2000 Mercedes Benz ML320

Engine Performance problem
2000 Mercedes Benz ML320 6 cyl All Wheel Drive Automatic 110000 miles

CHANGED MASS AIR FLOW SENSOR WHEN CAR ALMOST STOPPED RUNNING AND THREW CODE SHOWING MALFUNCTION IN MASS AIR FLOW SENSOR CIRCUIT - THOUGHT PROBLEM SOLVED - BUT CHECK ENGINE LIGHT IS BACK ON - SHOWS MALFUNCTION IN FUEL TRIM BANKS 1 & 2. AT FIRST THE CHECK ENGINE LIGHT WOULD GO OFF AFTER RUNNING THE CAR 3 OR 4 TIMES. NOW IT IS STAYING ON - SAME CODES - occasionally has a slight shudder at idle - DID I GET A BAD MASS AIR FLOW SENSOR?
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Rpstarr
June 10, 2010.



Hi
Would you post code in P0xxx format so I may acess info for causes?
Thanks for donate

Docfixit
Jun 14, 2010.
THE CODES WERE PO170 - FUEL TRIM MALFUNCTION (BANK 1) AND PO173 FUEL TRIM MALFUNCTION (BANK 2)
THESE CODES APPEARED AFTER I CHANGED THE MASS AIR FLOW SENSOR.

Tiny
Rpstarr
Jun 14, 2010.
Was code P0100 present before replacing MAF? Recheck the instlation most common cause for 170-173 together is intake leak

Docfixit
Jun 14, 2010.
YES PO100 WAS PRESENT BEFORE REPLACING THE MAF - CHECKED INSTALL ON MAF AND IT APPEARS TO BE PROPER - CHECKED BELLOWS AND COULD FIND NO CRACKS OR SPLITS - ANY WAY TO CHECK FOR LEAKS?
PROBLEM STARTED DURING WINTER - HAD TO WARM UP A LITTLE BIT OTHERWISE IT WOULD BOG DOWN - THEN ABOUT A MONTH AGO (WHILE DRIVING) IT STARTED BOGGING DOWN AND I ALMOST DIDN'T MAKE IT HOME. RAN THE CODES AND CHANGED THE MAF. EVERYTHING APPEARED TO BE FINE AND THEN 170-173 APPEARED AFTER SEVERAL DAYS. RAN THE DATA ON MY SCANNER AND IT SHOWS INTAKE AIR TEMPS THAT SEEM VERY HIGH (130-150)- THE TEMP HERE HAS BEEN IN THE MID 90'S !

Tiny
Rpstarr
Jun 14, 2010.
Have fuel pressure tested maybe faulty diaphram pressure regulator lowering fuel pressure

Docfixit
Jun 14, 2010.