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Air Mass Meter and Oxygen Sensor test results - do they need replacement? 200 1986

posted by  darmstrong on  Mon Jul 28 15:45 CST 2003
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last visit: Sat Sep 13 12:21 CST 2014
[RELATED]

Art:

I see now your point about not drawing conclusions on static oxygen sensor results. I did find some great examples of dynamic sensor waveforms(http://home.earthlink.net/~mgmcqueary/uses.html) Compared to these graphs, my sensor is very sluggish. My lean to rich transitions are about 0.25 seconds; rich to lean are sometimes 1.0 second for a full transtion. I take it that this is definitive proof that I need a new sensor.

What are the expected results when viewing the idle mixture test point under various driving conditions? Should it stabilize to a 50% duty cycle at various speeds? Is it expected to momentarily track differently on kickdown, etc.?

I thought your idea about having the idle mixture adjustment test point drive an available bulb in the instrument cluster was a great one, but are you sure the LH2.2 ECU will drive this bulb? When I hooked it up while viewing the closed loop transitions at the test point, the transitions stopped with the test point held at a high voltage (13v?). I'm assuming the test point could not sink the current required to keep the test point voltage low. Maybe there's a series resistor on ECU output, or do you think my output has a blown stage? I know the test jig has a 750 ohm resistor in-line, meaning that the maximum current it draws is about 12v/750 ohms = 16 ma. I believe I've read that the bulbs are about 2 watts, so the current would be 2/12 = 166 ma. It's too bad if it doesn't have the current capacity; the implementation was effortless. Simply remove the white/red tach wire from the coil and jump it to the test point with a male-male jumper, then connect the unused other end of the tach wire behind the cluster to the open lug to the left of the speedometer with another male-male jumper. I believe this drives the "choke" indicator which is 3rd from the left side.

Thanks for your offer of an AMM loan; I'm not sure with the border though, it's worth the aggravation (I'm near Toronto). I've posted my odometer experience separately.

Thanks,

David






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