air flow meter
12-28-2002, 05:18 PM
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air flow meter
The allen screw on the side of the air flow meter adjusts the mixture, c/w to richen, cc/w to lean.My question, what does this adjustment screw really do? Is it a sprimg adjustment for the door, or does it bypass air from the door, or is it some kind super secret info that the curious should not no.
Thanks,
Just want to know
86 944 N/A
Thanks,
Just want to know
86 944 N/A
12-28-2002, 10:26 PM
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The bypass is for adjusting CO levels. At idle most Bosch systems, closed loop .5% is a close CO reading. Readings down from the converter will of course be lower,,if you don't have a test pipe installed. The above .5% should be from the sampling tube if that is still around. Car should be warm and idle correct.
With the O2 sensor disconnected your CO should go up to about .9%. So now, the correct mixture, you need to lean or enrich the open loop mixture until it matches the closed loop.
If you use a volt meter on the signal wire of the O2 sensor to check the mixture,,, turn the screw CCW, lean should be the lowest voltage, CW to richen - voltage should climb, set the mixture in the middle of the voltage range and you will be close. If the voltmeter doesn't move you need a new O2 sensor - it is dead.
With the O2 sensor disconnected your CO should go up to about .9%. So now, the correct mixture, you need to lean or enrich the open loop mixture until it matches the closed loop.
If you use a volt meter on the signal wire of the O2 sensor to check the mixture,,, turn the screw CCW, lean should be the lowest voltage, CW to richen - voltage should climb, set the mixture in the middle of the voltage range and you will be close. If the voltmeter doesn't move you need a new O2 sensor - it is dead.
12-29-2002, 11:44 AM
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Question: What are the voltages I sould be seeing on the volt meter, and second, How many turns of the adjustment screw should be needed to see the high and low voltages
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12-31-2002, 01:46 AM
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With the car warmmed up and the O2 unplugged find the only one that sends it's own voltage from the O2. Should be 2 grey and 1 white two are for the O2 heater and one for the signal. Not sure witck are correct so I don't want to misinform you, If I guessed I would say the two grey are the heater and I don't think they make a difference as to pos. or neg. but the other is the signal. 