Here's some info on airflow meters, for better or worse. I made a $180 mistake a couple years ago by convincing myself my airflow meter was bad ( I had 'bogging' problems and 'low' [read typical] fuel mileage). I had taken the ohm meter readings per the tech manuals and the values jumped around when moving the air vane. I thought , "oh, its bad" and willfully paid for a new Bosch unit from the dealer. I checked the new unit, and its values also varied in a non linear fashion as I moved the air vane. I checked another van with similar results indicating a 'bad' unit. Engine performance/fuel mileage/drivability varied not a wit with the new unit. ( I kept asking my wife- 'it seems a little better, doesn't it?'). Anyway, as the saying goes, "Wisdom comes from experience. Experience comes from mistakes." On my quest ( and after my purchase) I called a place in Minneapolis specializing in high-end German cars. They said the *only* way to check out a suspected airflow meter was to put an oscilliscope on the voltage output lead of the airflow meter and move the vane while the harness is connected and the key on. A good meter will give a smooth voltage change on the oscilliscope screen-- a bad meter will result in skips and jumps in the displayed voltage. They faxed me an internal wiring diagram for a 4-lead airflow meter (manuals sometimes show an internal diagram of the 6-lead ones). Here's the pin breakdown on a 4-lead meter as found on at least '83-'85 Vanagons: Pin 9 - Input Pin 8 - Reference voltage Pin 5 - Ground Pin 7 - Wiped output (the one that varies with the vane movement) So, attach the oscilliscope to Pin 7 (by back-probing thru the harness) and a ground. I did have an airflow meter fail on a Toyota. The symptoms were an extremely sharp engine cut off at very specific rpms. Other rpms ran flawless. The dealer said it was a $550 item so I took mine apart to see if it was repairable (prompted by the dealer assertion that there was no way one could repair one). Everything looked good with no burned spots on the carbon resistors so I took a pencil eraser and gently cleaned the carbon track. Then I used piece of paper card-stock to clean the underside of the wiper. Put it all back together, resealed the plastic lid with silicone sealer and have had a perfectly running airflow meter for the last 50,000 miles! Somenone had posted a repair by elongating the mounting screw holes to present a different portion of the carbon track, this sounds like a good idea too, especially if the wiper has worn a groove in the track. Airflow meters DO go bad, the individual carbon resistors and/or the carbon track can burn out. But I'm sure suspect of the diagnostic procedure using an ohm meter.
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