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05-14-2013, 12:23 PM | #1 |
Scooby Specialist
Member#: 310506
Join Date: Feb 2012
Chapter/Region:
South East
Location: Florida
Vehicle:2005 WRX STi CGM |
MAF / O2 Sensor voltages
Hey guys,
I've got an 05 STI with: - TGV Deletes - APS TIP - APS CAI - TMIC The car was protuned with all of these mods installed. I'm having an issue where my car is running very rich in boost, and i'm trying to track down why. My AF stored values (from LV) are very low. I replaced the Front o2 sensor, and now i'm turning my eye towards the MAF sensor... I noticed the voltage levels in this log; are these normal for the MAF and o2 sensor? When I took it to the dealership to get the Subaru select on it, I told them it was running rich. They said that it seemed like somewhat erratic o2 sensor readings (voltage?). https://docs.google.com/file/d/0B0i3...it?usp=sharing Thank you guys! |
05-14-2013, 01:25 PM | #2 |
Scooby Guru
Member#: 51961
Join Date: Jan 2004
Chapter/Region:
RMIC
Location: Broomfield, CO
Vehicle:2005 STi 2012 WRX |
How do you know it's running rich in boost?
When you're in boost the system is in open loop, so other than the learned fueling adjustment the O2 is having no effect. If the AFR Learning looks normal, the O2 sensor cannot cause a fueling problem in open loop. |
05-14-2013, 02:37 PM | #3 | |
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Join Date: Feb 2012
Chapter/Region:
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Quote:
I cleaned the MAF sensor, and it changed how the car ran. My A/F Learning stored sorted itself out, but I was still running super rich. So what are the only possible causes at this point? |
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05-14-2013, 03:08 PM | #4 |
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Well make sure your AFR Learning is in good shape, since this is calculated and modified in closed loop, but is still carried over and applied in open loop. Generally less than 3% is considered good.
Beyond that, a bad MAF, bad MAF scaling, or boost leaks are the main causes for running rich in boost. |
05-14-2013, 03:21 PM | #5 |
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It was at about 6% for A, and 3% at C, but there aren't any boost leaks (multiple boost / smoke tests confirm), and no mods have done since it was tuned (added Walbro LPH 255 pump, however).
I suppose it has to be the MAF sensor then. Could FPR have anything to do with this? |
05-14-2013, 03:26 PM | #6 |
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When did the rich business start? The fuel pump could be the culprit.
Usually a fuel pump change won't cause this, BUT you were professionally tuned before you got it. The tuner could have easily been compensating for a drop in fuel pressure from the insufficient pump by jacking up the MAF scaling. Now that the fuel pressure problem has been fixed with the new pump, that MAF scaling adjustment would now be making you run too rich. |
05-19-2013, 09:57 PM | #7 | |
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Quote:
Numbers displayed is percent. Steve @ Pullz-On Tuning |
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05-14-2013, 03:51 PM | #8 |
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Not sure. I installed the FP about 8 months ago, as recommended by my tuner. At that time he said i shouldn't need a re-tune for it.
Car has been down on power for almost a year, but I got a wideband a couple of months ago, and noticed it was just dumping fuel. Started really trying to get to the bottom of it recently. |
05-15-2013, 06:44 PM | #9 |
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Anything I can do to confirm this?? Or test the maf maybe?
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05-15-2013, 07:10 PM | #10 |
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05-16-2013, 11:43 AM | #11 |
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He said it was way too rich, but wasn't able to really help me diagnose the issue.
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05-16-2013, 12:29 PM | #12 |
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Did he experiment with tweaking maf scaling at all to see if it helped?
Steve @ Pullz-On Tuning |
05-16-2013, 04:10 PM | #13 |
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No, he actually retired from tuning, unfortunately.
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05-16-2013, 04:25 PM | #14 |
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05-16-2013, 04:21 PM | #15 |
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OP, I did notice that your AF learning A range was as high as 7% at idle. You could have a bad o-ring at the maf sensor causing a a vacuum leak which you would not have discovered leak testing. You also didn't say what AF learning D was which can get carried over and applied in OL unless your tuner effectively turned that off. If AF learning D is still enabled and positive it could be making you richer.
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05-16-2013, 04:59 PM | #16 | |
Scooby Specialist
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Join Date: Feb 2012
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Quote:
B = -0.5 C = 3.40 D = 0 and we replaced the o-ring with another type of o-ring, but the actual plastic that holds the o ring was deteriorating. I'm located in Lutz / Tampa! |
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05-16-2013, 05:19 PM | #17 |
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05-16-2013, 05:40 PM | #18 |
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The APS Intake has a 3" diameter
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05-16-2013, 05:46 PM | #19 |
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I was gonna say, I have a local car I recently did with a 70mm APS intake and I could compare the MAF scaling to see if your tuner was compensating for a bad fuel pump with the MAF scaling....
Steve @ Pullz-On TUning |
05-16-2013, 05:54 PM | #20 |
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Actually - I think it is 70mm, come to think of it. What do you need to see? The ROM?
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05-17-2013, 08:39 AM | #21 | |
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Quote:
Yea. Email it to me. [email protected] Steve @ Pullz-On Tuning |
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05-17-2013, 01:04 AM | #22 |
Scooby Specialist
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Hey guys, I took some logs today and was increasing the IAM, and caught the IAM dropping in the log from .75 to .625~. I don't really see anything causing knock etc, or fueling issues that caused the drop. I also noted that the Fine learned knock tables had 0's all across the board.
What do you guys think? What else am I missing? https://docs.google.com/file/d/0B0i3C9x11ZNVZGU2azV2Z0ZwNlk/edit?usp=sharing[/url] Last edited by BeastianSTI; 05-17-2013 at 09:10 AM. |
05-17-2013, 08:24 AM | #23 | |
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Quote:
See: http://www.romraider.com/forum/topic1840.html |
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05-17-2013, 09:29 AM | #24 | |
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Quote:
Last edited by BeastianSTI; 05-17-2013 at 09:34 AM. |
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05-17-2013, 09:05 AM | #25 |
Scooby Specialist
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https://docs.google.com/file/d/0B0i3...it?usp=sharing
Sorry guys, there is the link! |
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