99 Buick Regal 3.8l only runs with MAF unplugged - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 05-05-2011, 11:40 PM   #1
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Default 99 Buick Regal 3.8l only runs with MAF unplugged

I have a 99 buick regal with the 3.8l series II motor. if you leave the MAF sensor plugged in the car tries to start and dies immediately. if I unplug the sensor the car starts and runs and if I plug the sensor back in while the engine is still running it will run for about 15 to 20 seconds and then die. The sensor is new. it is getting 12 volts from the ignition at terminal C and a good ground at terminal B and I am getting a output through terminal A. could it be a defective maf sensor?
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Old 05-05-2011, 11:42 PM   #2
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It very could well be a def sensor..Any SES lights
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Old 05-05-2011, 11:43 PM   #3
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I also forgot to mention that the only time I get any fault codes is when the maf sensor is disconnected. I get the p0102 due to no maf signal present.
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Old 05-05-2011, 11:48 PM   #4
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Make sure it'* the correct MAF. However, seeing it runs unplugged and dies when plugged in that would tell me it'* a bad MAF. However, there is still a chance the MAF is good and you have a bad connection in the wiring harness plug. I found that once.
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Old 05-05-2011, 11:56 PM   #5
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I think I will try replacing the MAF with another one and see what happens. I would think if the connection was bad I wouldn't be getting any output signal from terminal A. the only testing I can find for the maf sensor requires seeing the frequency output from terminal A and the car won't run long enough to get a accurate change in frequency with the sensor connector plugged in.
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Old 05-06-2011, 12:04 AM   #6
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The best way to get that data is to scan the car at the OBD2 port with something like a aeroforce scan gauge or software that can scan live date. Some can be bought for as little as around $100
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Old 05-06-2011, 08:07 AM   #7
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Do you have the numbers off the top of the maf? We should be able to verify it'* right or not.

Also when you disconnect the maf before starting, this reverts the pcm to a table. Tables aren't perfect. I'd suggest keeping it running with some throttle for a minute or two. Then it should be able to hold it'* own idle and as the pcm adjusts/learns you'll notice it runs much better.

However the ideal and fuel efficiency of the sensor make it necessary. Where did you get the new sensor?
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Old 05-06-2011, 09:00 AM   #8
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the part number on the MAF sensor is MF5288S. I started the car and let adjust so it would idle with the sensor disconnected and then plugged the sensor in and checked the frequency at idle on my scanner and it showed 8,220 hz just as the car dies.
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Old 05-06-2011, 09:10 AM   #9
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That seems very high for idle. I'm kinda thinking thats the wrong sensor. I'm used to seeing the sensor say AFM05-04 or 05 for your year. (GM numbers on the sensor).
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Old 05-06-2011, 09:13 AM   #10
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A little high? Try a lot high. Just checked a bunch of scans and I'm showing 2500 to 3000 hz at idle.
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