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Old 01-07-2021, 07:39 PM   #1
Conster102
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Member#: 519178
Join Date: Oct 2020
Unhappy DAM Stuck at 8

2003 WRX 5MT

Only mod is a catless up pipe

I run lean based off of A/F correction being positive especially under WOT but I have no vacuum leaks, no exhaust leaks, my MAF is working properly and I just replaced both A/F sensors in the exhaust. Car is on stock tune. What could it be?

Log of just cruising for a little bit but can definitely log more if asked: https://drive.google.com/file/d/1hRH...ew?usp=sharing

Please help thank you
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Old 01-07-2021, 08:01 PM   #2
awfulwaffle
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2005 LGT
ABP

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Your top range fuel trim is almost pegged, and it looks like it gets progressively better at lower airflows (though still high in at least range C). I only have experience with 32 bit ECUs so maybe it's different in your case, but you shouldn't be seeing any A/F correction at WOT since your car's in open loop and A/F correction only gets applied in closed loop fueling. Maybe you mean A/F learning? In this case, this value is learned and stored in a lower power regime (closed loop fueling) but gets applied when you're at WOT.

I'm barely seeing any transition to open loop fueling in your logs, but when it does happen towards the end of the mini-pulls you did the AFR looks about where it should be w/ the stock sensor. This is probably only because your top fuel trim is being applied, and it may lean out at actual WOT. I wouldn't do any more WOT pulls until you figure it out, though.



In any case - if you have verified for sure that the MAF is good, the front O2 sensor is good, and there are no vacuum leaks, I'd take a look at the air filter to make sure it's not super dirty and after that start looking at fueling. Verify fuel pressure tracks with manifold pressure as it should. It should be at 41-46 psi with the vacuum reference line disconnected. When connected, the value should be the hose-disconnected value plus whatever the manifold pressure is. For example, when you're in vacuum at, say, -8 psi, the fuel pressure should be between 33 and 38 psi. Make sure you check this with a little bit of throttle too, to see what happens when there's a little more demand for fuel. Again, no WOT. If all of that is good, start thinking about injectors.

Last edited by awfulwaffle; 01-07-2021 at 08:25 PM.
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Old 01-07-2021, 09:19 PM   #3
AcquaCow
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Chapter/Region: MAIC
Location: Reston VA
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2001 B50 RSTi Sedan
2011 DGM WRX hatch

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Stuck it into datazap for folks... much easier to see:

https://datazap.me/u/acquacow/conste...a=1-4-15-16-18
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Old 01-08-2021, 02:21 AM   #4
Conster102
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Thank you so much for the informative post! So I understand the formula and I want to try it but where is the vacuum reference line? I tried a quick google search and could not find it. Also that datazap thing is super cool thank you!
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Old 01-12-2021, 11:06 PM   #5
Conster102
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I took out my fuel injectors and got them flow tested they got cleaned and are delivering fuel at max capacity and replaced my fuel filter. Still have the same issue so what could it be? Subaru said my MAF was good but only because it was delivering normal numbers has anyone had a MAF show decent numbers but still be bad? I don’t think it’s the fuel pump otherwise the issue would be more noticeable right?
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Old 01-14-2021, 12:21 PM   #6
86Dreams
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'21 Giulia Q4

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Quote:
Originally Posted by Conster102 View Post
I took out my fuel injectors and got them flow tested they got cleaned and are delivering fuel at max capacity and replaced my fuel filter. Still have the same issue so what could it be? Subaru said my MAF was good but only because it was delivering normal numbers has anyone had a MAF show decent numbers but still be bad? I don’t think it’s the fuel pump otherwise the issue would be more noticeable right?

can you post another log and include Boost as one of the parameters?
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Old 01-29-2021, 11:39 PM   #7
Conster102
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Yo it’s alright thank you guys for all the advice my car is now working 100% as intended. I asked NateWade Subaru to do literally 1 thing and it was to test my MAF sensor and they said it was fine. Replaced my MAF sensor and it fixed everything :/
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