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12-12-2013, 03:56 PM | #1 |
Scooby Newbie
Member#: 116797
Join Date: Jun 2006
Chapter/Region:
South East
Location: Melbourne, FL.
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I have an issue with my MAF sensor returning low readings to the ECU. My tuner has been working for weeks now with me trying to get to the bottom of this. I have swapped the MAF sensor with one from another car that has about 60k on it. My current sensor has 120k. Everything else seems to be fine. I have performed a smoke leak test and there was a leak at the stock OEM post MAF hose, but I fixed that by replacing it with a COBB Post MAF hose. It still shows low readings. It has been cleaned using MAF sensor cleaner. The readings are approx. 100 g/s off. For instance right now it is reading 4.14v @190 g/s. It should be reading a lot higher. Any thoughts on what we could be missing?
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Last edited by Ravel36; 12-12-2013 at 04:04 PM. |
12-12-2013, 03:58 PM | #2 |
Scooby Newbie
Member#: 116797
Join Date: Jun 2006
Chapter/Region:
South East
Location: Melbourne, FL.
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04 sti turbo back exhaust, 1 step colder ngk, cobb sri. Perrin EBCS, AEM UEGO Wideband, 255lph Walbro.
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12-12-2013, 05:42 PM | #3 |
Scooby Newbie
Member#: 356635
Join Date: May 2013
Location: California
Vehicle:2005 STI WR Blue |
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12-12-2013, 06:02 PM | #4 |
Scooby Newbie
Member#: 116797
Join Date: Jun 2006
Chapter/Region:
South East
Location: Melbourne, FL.
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Yea I don't know, but right now we have it at stock boost. Does that sound like a bad MAF? I am considering spending the 200 bucks to get a new one.
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12-12-2013, 06:10 PM | #5 |
Scooby Newbie
Member#: 356635
Join Date: May 2013
Location: California
Vehicle:2005 STI WR Blue |
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12-12-2013, 06:21 PM | #6 |
Scooby Newbie
Member#: 116797
Join Date: Jun 2006
Chapter/Region:
South East
Location: Melbourne, FL.
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I am not sure if the mapping that I have is stock or not, and I don't have the original oem map. The tune is not stock, but I don't know if the MAF scaling or map scaling is stock.
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12-12-2013, 06:22 PM | #7 | |
Scooby Newbie
Member#: 356635
Join Date: May 2013
Location: California
Vehicle:2005 STI WR Blue |
Quote:
Do you have the ability to flash the ecu? |
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12-12-2013, 06:32 PM | #8 |
Scooby Newbie
Member#: 116797
Join Date: Jun 2006
Chapter/Region:
South East
Location: Melbourne, FL.
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I do, the tuner, who in my opinion seems to be pretty competent, stated that it's not the scaling that's the concern. We have been tuning, so I take logs and email the, to him, he sends me a revised ecu map and I reflash.
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12-12-2013, 07:35 PM | #9 |
Scooby Newbie
Member#: 356635
Join Date: May 2013
Location: California
Vehicle:2005 STI WR Blue |
Well I show 4.1volts would be right around 190g/s. On a stock maf scale. Perhaps you have a pre turbo leak? Somewhere post maf...
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12-12-2013, 07:48 PM | #10 |
Scooby Newbie
Member#: 116797
Join Date: Jun 2006
Chapter/Region:
South East
Location: Melbourne, FL.
|
No leak. I had that checked. We'll not pressurized, but with a smoke machine.
If the readings I have match what you have for a stock scale, then it seems to me that there is no issues. Your thoughts? |
12-12-2013, 07:51 PM | #11 |
Scooby Specialist
Member#: 137405
Join Date: Jan 2007
Chapter/Region:
MAIC
Location: Baltimore
Vehicle:2011 WRX 6spd GTX3076r |
you sure you don't have a map that has the "half maf hack?"
basically to get the maf to support higher g/s someone somewhere figured out to scale the maf and injectors differently to get the maf to support more power on the 16bit ecus. In turn the maf readings will appear lower than they really are. |
12-12-2013, 08:06 PM | #12 |
Scooby Newbie
Member#: 116797
Join Date: Jun 2006
Chapter/Region:
South East
Location: Melbourne, FL.
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How do I tell if it is a half MAF? My ecu is 32 bit
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12-12-2013, 09:33 PM | #13 |
Scooby Newbie
Member#: 356635
Join Date: May 2013
Location: California
Vehicle:2005 STI WR Blue |
I think the person who posted the half MAF comment missed that you had an 04 STI. All the STI's had 32 bit ECU's which are scaled to 348g/s stock. Of course the CEL limit is 300g/s stock, but that's easy to change. The 16 bit WRX ecu's were limited to 292. Im not too familiar with the whole "half MAF" deal, but I would assume you would need to run a larger diameter MAF housing and then rescale the MAF to where a lower voltage indicated are higher airflow value. The ECU uses the airflow measured from the MAF sensor to calculate injector pulsewidth needed to hit the target AFR in your maps. Anyways, I digress. I am pretty sure this is not your problem.
G/s flow is generally accepted as a rough calculation for horsepower to the wheels. A stock STI in good health has been shown to dyno typically in the 240-255ish range. That being said, stock I would be looking for flow figures in this range. If your only showing 190 on a stage 2 STI, I would say for sure something is "wrong". |
12-12-2013, 09:55 PM | #14 |
Scooby Newbie
Member#: 116797
Join Date: Jun 2006
Chapter/Region:
South East
Location: Melbourne, FL.
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Ok thanks for the input. I think I will go ahead and by a new MAF and see what happens, before I do so, does anyone happen to know how to test a MAF sensor to see if it is good or bad.
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12-12-2013, 10:09 PM | #15 | |
Scooby Specialist
Member#: 137405
Join Date: Jan 2007
Chapter/Region:
MAIC
Location: Baltimore
Vehicle:2011 WRX 6spd GTX3076r |
Quote:
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12-12-2013, 10:10 PM | #16 |
Scooby Specialist
Member#: 137405
Join Date: Jan 2007
Chapter/Region:
MAIC
Location: Baltimore
Vehicle:2011 WRX 6spd GTX3076r |
I'd find a local guy(look in your areas' sub forum) with a known working maf and see if they'd can swap their maf in temporarily and see if you have the same issues.
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