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I think that my MAF sensor is bad. Well, I am getting a P0100 and P0101 error thrown. So I did a bunch of digging around online and found some info on how the MAF is supposed to operate and what pins are what.
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/ __ __ __ __ __ \
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1 2 3 4 5

Supposing the above is the MAF harness plug (the front, as in looking at the leads while the wires are behind the picture), then:
1)MAF Power (12V from pin 1 to Batt(-))
2)MAF Ground (12V from pin 2 to Batt(+))
3)MAF signal out (1.1-1.4V @ idle, 4.5V @ max RPM)
4)IAT signal out
5)IAT ground

Pins 4 and 5 I got from a lotus forum but they use the 2zz as well:
http://www.lotussport.org/viewtopic.php?f=8&t=3414
I didn't test my pin 4 because I thought that it was power at first when I was getting a 5V reading from it.

It is my understanding that pin 3, the signal out of the MAF, should be stable. I have never tested any other MAF than the one I did today, so i am not sure what constitutes stability. I have posted a video showing the signal readings on youtube:
http://www.youtube.com/watch?v=V0qMRaFV2SM&feature=youtu.be
There is a point at about 14-18 second where I rev the engine 2 separate times each to about the same RPM but get very different output voltages (the first time I get the predictable 2.6V, but the second time I get the unpredicted 1.9V). I noticed this when I was testing it, if I do not let the engine reach idle RPM, but instead rev it back up, then the voltage generated by the MAF is always lower than if I just revved the engine from idle to that RPM. I am very confused with it.

I know that something has to be wrong, my ECU is throwing P0100 and P0101 which are MAF and IAT errors. In addition, the engine sounds like it is running rich at low RPM, and has very little power at the same time. I have even gone so far as to remove the MAF harness plug and then drive the car, and it makes no difference if the MAF is attached or not (except that when it is not attached the CEL is on). Everything that is wrong with the engine points to a bad MAF but the MAF seems to be returning proper values.

PLEASE HELP ME!!! I have put a lot of time into this one and it is killing me to run my poor celi like this. I have the feeling that it is killing my O2 sensors too if the MAF is not working since the timing will be off and there will be excess fuel in the exhaust air.

THANKS FOR ANY HELP!!!
 

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Discussion Starter #3
Based on what the service manual says I would think that my MAF is fine. The voltage to the MAF and IAT are 12V, and the signal out is as expected (though it may be fluctuating a bit). This, then, does not make sense why my ECU would throw an error about the MAF. I am going to reset the ECU and try again. Maybe I didn't reset it properly last time.
 
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