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Even though testing the AMM by measuring resistance between 6 and 7 is a factory manual procedure, it in no way tests the amm. It actually verifies a film resistor, part of the bridge, is intact - something that would likely never go bad. Not the platinum wire.
The limp home mode takes effect when the output is out of range during operation, but with LH2.2 in your 86, I'm fairly certain there is no storage to be reset by disconnecting power. That learning feature is new in 89 with LH2.4.
Problem with the AMM, is they go bad subtly, by shifting the voltage range for a particular air flow just by a few hundred millivolts. This won't be measured by resistance readings, but if the unit is not dead - as in broken wire - it will just run out of the range your oxygen sensor can correct. A better way to test the air mass meter is to backprobe its output pin (7 - w/r) with ignition on but engine not running. Resting voltage will be somewhere near a volt and a half. Start it and it should run in the high twos almost three. Turn the motor off, disconnect the input air elbow from the airbox. Turn ignition on, probe pin 7 and waft some air near the AMM screen. Blow on it. You should see very sensitive response to air movement.
The CO pot on the AMM is a fine adjustment. The mixture has to be very close to stoich for this pot to do you any good. It has no function at all in the measuring of air mass, but serves to match an AMM to a particular ECU, both of which are calibrated (analog) but not perfect.
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Art Benstein near Baltimore
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