03 Regal runs good with MAF unplugged - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 08-26-2012, 12:21 AM   #1
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Default 03 Regal runs good with MAF unplugged

I have a 2003 Buick Regal that my daughter drives. Monday she put gas in it and Wednesday it died in rush hour. Seemed like it was starving for gas so changed the TPS on some advice, no luck. Changed the fuel filter, ran for about two miles, died at an idle then wouldn't start. Under the wrong advice from the local parts store changed the fuel pump because it showed 50 psi and they told me it should be 85 psi (they were wrong). Went to load it on a trailer to haul it home and on a whim I unplugged the MAF sensor and it ran fine. Drove it the eight miles home, plugged in the MAF sensor and it loaded up with gas and died. Cleaned with MAF sensor cleaner, no luck. The only time it throws a code is when it is running and I plug the MAF in (low voltage). No codes when MAF is unplugged. About everything I have read says the MAF is bad. I understand that by uplugging the MAF I am bypassing some other important readings such as O2 sensors. Should I look at something else or bite the bullet and replace the MAF? Any help is greatly appreciated as I am not a mechanic. We are $360 dollars into this and it still is not fixed.
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Old 08-26-2012, 05:19 AM   #2
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If it runs fine unpugged, then its the classic MAF failure. But not a complete failure. It'* still sending a signal to the PCM but very different from normal, so the PCM thinks its working fine.
And no, it doesn't bypass the O2 sensor. The PCM just uses a predertimined set of values based on cylinder air mass volume. Its like a fall back.

So yea, get a new one.
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Old 08-26-2012, 05:46 AM   #3
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Thanks for the reply Mike. I will grab one tomorrow and see how it does. Do I need to do anything to reprogram my computer after installing the new MAF?
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Old 08-26-2012, 06:28 AM   #4
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No sir. Plug-n-Play.
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Old 08-31-2012, 04:31 PM   #5
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Just wanted to touch base and say thanks again. The problem wound up being the MAF sensor [I]and[I] the connector or wires. I finally took it to a mechanic he determined the problem and fixed it.
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Old 09-16-2012, 09:29 PM   #6
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Good to hear you got it fixed up! Those 3800'* are notorious for MAF sensor failures.
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Old 09-17-2012, 12:09 AM   #7
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Well....the problem isn't resolved. After getting it back, the check engine light is on. Now it is throwing the P0420 catylitic system bank one below thresh hold. We have replaced the upstream O2 sensor cause the mechanic doesn't think the convertor is bad. The light still comes on. I don't know what the next step is.
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Old 09-17-2012, 12:32 AM   #8
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Quote:
Originally Posted by stuartsx5 View Post
Well....the problem isn't resolved. After getting it back, the check engine light is on. Now it is throwing the P0420 catylitic system bank one below thresh hold. We have replaced the upstream O2 sensor cause the mechanic doesn't think the convertor is bad. The light still comes on. I don't know what the next step is.
It'* always good to replace the upstream sensor, but try replacing the downstream O2 sensor before you declare the catalytic converter bad.
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