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Old 04-30-2013, 02:51 PM   #1
Brandong
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2008 WRX Hatchback
Lightning Red

Default Bad MAF sensor voltage and CEL :(

Hey guys, I have a 2008 WRX and I need some input on this. I am running a COBB SF Intake system with AccessPort Stage 1 91 Octane+ SF,and Perrin Catback. I recently got a P0171 code ( system running lean), so I went to the dealership to let them check it out. After a lot of hassling me because of my mods, they tried telling me my MAF sensor was going bad and that I should put my stock intake back in and buy a new sensor. So I went home and checked the voltage and it was at 1.1V at idle and 1.6V at full throttle. I had them check all vacuum lines and look for leaks but they didn't say anything bad about them. I have tried cleaning the MAF sensor with MAF sensor cleaner a while ago. Also my car Revs at 1k-2k RPM's with rough idle and some times rough driving.
Any help with this would be much appreciated!
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Last edited by Brandong; 04-30-2013 at 09:39 PM.
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Old 04-30-2013, 02:55 PM   #2
Paidfor
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You killed it with that brake cleaner..clorinated or not....that **** melts plastic, imagine what it did to the little elements inside the MAF. Im not sure on your correct voltage readings but brake clean on a MAF is almost certaily death.


Use MAF sensor cleaner.
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Old 04-30-2013, 02:57 PM   #3
Brandong
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WHOOPS i definitely did not mean brake cleaner, i meant MAF cleaner......... fail.
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Old 04-30-2013, 03:06 PM   #4
sultan81
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Did you try what the dealership suggested?
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Old 04-30-2013, 03:09 PM   #5
Brandong
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Not yet, I am seeing what some peoples input is first before i spend the money on a new sensor. I will probably end up going back to stock intake though.
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Old 04-30-2013, 04:59 PM   #6
Snowy
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Sounds like the MAF has failed, I would recommend an OEM quality sensor, not autozone cheepy. Over oiled airfilters can easily take out MAF sensors, also an under oiled filter will do that too. MAF's are very sensitve to contaminants (dirt/oil) they function by heating either I wire resistor or thick film up to 350f and then measure the current required to maintain that temp. The more airflow over the sensor the more power to heat the wire, coat the wire in oil or dirt and the readings get thrown off. I have had about 3/10 chance of cleaner fixing a dead MAF, I recommend more of a preventative cleaning, every oil change with oiled filters, or when you replace a dry paper filter.
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Old 04-30-2013, 05:11 PM   #7
Brandong
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I just drove my car again and I got new volt numbers, 1.5V-3.5v full throttle. Still 1.1v idle. Thanks snowy for the information.
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Old 04-30-2013, 09:37 PM   #8
Brandong
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Anymore opinions?
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Old 05-01-2013, 12:08 AM   #9
Snowy
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those numbers are more in line with normal. though even slightly shifted readings will still cause problems. can you post a log of MAF, TP, RPM, MAP, A/F R, Fuel trim? If you see the MAF readings dropping under WOT but the Fuel trim is going rich it is 100% a MAF problem.
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Old 05-01-2013, 03:33 AM   #10
Brandong
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whoops

Last edited by Brandong; 05-01-2013 at 03:50 AM.
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Old 05-01-2013, 01:57 PM   #11
Brandong
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Lightning Red

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Here is one data log... unfortunately its not WOT because day driving sucks. but ill be getting another one tonight. This is what I should have logged correct?

https://docs.google.com/spreadsheet/...FE&usp=sharing
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Old 05-02-2013, 02:49 AM   #12
Brandong
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Default Real

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Old 05-23-2013, 09:42 AM   #13
sexyyrex
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Quote:
Originally Posted by Brandong View Post
I have a MAF sensor for sale if you want to try.
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