Quote:
Originally Posted by VMAX1
Can't get it under 13v, no mater where the air flow screw is adjusted?
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Normal is 0.1 to 0.9 volts DC. If you're getting 13+ volts then sensor is bad, meter is bad, or you're not testing properly (wrong DMM scale, or O2 sensor is outside proper operating/testing temps -- 600F+ per Bentley). Or perhaps you're reading the wrong wire; if you have a 3-wire O2 sensor you could be reading the battery-side voltage of the heater lead and not the sensor output lead. I don't think even wideband O2 sensors have 13+ volt range, even if bathing in liquid fuel 13VDC is way off.
Quote:
Originally Posted by VMAX1
Will a dirty AFM cause an O2 sensor reading like this?
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No. O2 sensor voltage drops w/lean condition (> ~14.7:1 stoichiometric / ~1.0 lambda). If running rich enough to show 1.3VDC (much less 13VDC) then it'd be so rich I doubt it would run at all. Wouldn't be vacuum leak either, as false air would cause it to run leaner -- not richer -- than AFM measures.
Quote:
Originally Posted by VMAX1
Can I spray intake cleaner directly into the AFM? The can directions say not to spray directly into any mass air flow units.
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Am assuming, per your garage, yours is 1987 3.2 Motronic w/stock AFM. AFM uses a movable flap/vane to measure incoming air. Combined w/air temp sensor to adjust for air density, this is what measures intake air for DME computer. If you inisist on cleaning your AFM, pull it off the throttle and use short bursts of CRC Lectra-Motive (red can, available at your FLAPS) along with a toothbrush and paper towels to clean the inside of the AFM. Better access if you remove, and you'll get all of the crud that way. But, per above, it's not the cleanliness of your AFM.
Again, assuming yours is 1987 3.2 Motronic, you do not have MAF (mass air flow). MAF uses a heated, thin gauge wire (made of platinum, I think) to measure air flow. As air rushes by the heated wire, the wire cools and resistance value changes. More air flow = greater cooling = more resistance change. Each MAF has a specific output that -- based on the cross-section of the sensor (diameter of tube) -- transaltes into voume and density of air to the engine management computer. You shouldn't use any kind of chemical cleaner in a MAF since they can leave a residue on the wire which leads to out-of-range readings. Besides, MAF sensors almost always incorporate a short heat-up cycle of the wire on start-up to burn off any contaminants. In short, they're designed to be self-cleaning.
How about providing a few details of running condition, and what's happening w/your car's performance that's leading you to these diagnoses? That'd make it a little easier to help us point you in the right direction.
Dale