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Discussion Starter #1
I'm throwing a p0101 code for MAF.There is three wires a red which is 13volts and power I assume a black which is ground and a white which tests at 4.4 volts and I assume is the signal wire .when I accelerated the 4.4 signal wire slowly dropped to 4.1. I was revving really high just to get it to drop to 4.1. Usually when I test mass air flows as I bring up the engine the number increases not decreases. I have four different mass air flows all from the junkyard and everyone I tested did the same exact thing. I'm wondering if they're all bad or if there's something I'm missing here. If anyone can help I would really appreciate it. Am I testing a correctly I'm on voltage DC. I tested for the ground using ohms that's how I came up with the black wire as ground. Can someone tell me what I'm supposed to be coming up with for numbers.
 

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Discussion Starter #2
I just wanted to add that the car is throwing the mass airflow sensor but I believe the car has a clogged catalytic converter. The car has 200,000 miles brand new plugs brand new ignition cassette. And the throttle body is in working order but for some reason the car starts to hesitate when it gets to about 20 to 30 miles an hour. And it's throwing codes for the mass air flow and the throttle body I can't find anything wrong with the throttle body the mass airflow I'm not sure. But my gut is telling me it's got a clogged catalytic converter. I'm going to test manifold pressure or test before and after the cat to try to come up with an answer on whether or not the catalytic converter is clogged but any help with testing the mass air flow would be greatly appreciated thanks a lot.
 

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Discussion Starter #4
I should have mentioned that yes if you unplug the MAF it runs exactly the same . I changed the throttle body. it wouldn't idle now that I changed the throttle body it's idling fine but when you start to take off it's fine right about till 20 25 miles an hour and as soon as you hit the gas it starts to buck. I was going to get a infrared heat gun and take some temperature readings at the beginning of the cat and the end of the cat to see if it's clogged or not.
 

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Based on your knowledge, I'm sure you know this, but what the frick. I would go over every frickn hose/pipe downstream of the maf to make sure you don't have a leak somewhere.
 

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Discussion Starter #7
I did go over everything I mean everything the hoses believe it or not are in good shape the guy who owned this car was a kid but him and his father ran a used Saab dealership. The car has 200,000 miles and an original catalytic converter that's what leads me to believe that the catalytic converter is the issue it feels like the car is choking out and there's something else I feel like there's a problem buried in this car somewhere and that's why they got rid of it just based on some of the codes and I'd have to look them up again but they came back to the throttle body saying malfunction certain circuits I haven't had a chance to go over the pens yet and figure out what's what I just switched out the throttle body to see if that would cancel it out since I haven't gotten the car back to good yet I'm not a hundred percent sure that the problem solved all I know is that it's idling and it wasn't idling. To be honest I just wanted to know how to test the MAF for myself for when I'm working on any saab. Normally when I test an MAF the signal wire will start to go up as I raise the idle on this vehicle it's going down and not very far like I said from 4.4 or 4.3 to 4.1 at 5000 RPM. I tested for different MAF on the car and they all did the exact same thing I find it hard to believe they're all broken. I can't check mine because my car is a part I'm doing a transmission swap. I guess I'm going to have to pull mine off the one I know that's good put it on this other vehicle and test it because whatever that one does I'll know that's what it's supposed to do I was just hoping someone had tested them before with the multimeter and knew exactly what I'm supposed to be seeing most of the ones I test nowadays have four wires these of course only have three.
 

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I would probably not try to read voltage off the MAF, especially with a DMM. The averaging is going to wipe out the subtle variations that actually mean anything. I'd think you'd really want a scan tool so you can "see" what the ECM is reading from it in terms of flow... g/m etc. Live data scan tools are pretty cheap these days - there's no reason not to have one in the toolbox!
 

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Discussion Starter #10
Based on the temps I read from the cat I'm pretty sure that it's clogged.it was about 500 degrees at the start and just 2 inches in its already 250 degrees.Based on those numbers I'm going to change the cat.Hopefully it'll solve the issue.it makes a lot of sense.im guessing the maf was triggered by the hot air backing up it can definitely explain away a lot of strange behavior.Thanks for the help much appreciated.
 

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T7 engine management system MAF sensor has a frequency output

per the Workshop Information System (WIS). If your digital multimeter has a frequency (Hz) option, you can read output on white/pink wire. 100 Hz at engine stop with ignition ON. Then increases to about 1000 Hz at idle. As engine speed increases above idle, frequency increases further. Earlier Motronic engine management MAF sensors had a voltage output which increased as engine speed increased.
 

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Discussion Starter #13
Thank you Wal while the comic relief is badly needed and in this case a flat bed to a junk yard as well I greatly appreciate the info.ive tried several times to download the wis on an older 64 bit computer with Windows 8 I just can't seem to look at it once it's downloaded to mega.thats another thread entirely though.thanks again.
 
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