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11-01-2019, 12:23 PM | #1 |
Scooby Newbie
Member#: 507940
Join Date: Nov 2019
Chapter/Region:
MWSOC
Location: WI
Vehicle:2002 wrx white |
Lean afr/bad idle, cant figure out why.
I just bought my wrx last Saturday and ive been having an issue that I cant seem to figure out.
At idle my afr gauge (passport) reads an afr of 17 and the idle sounds lopey. Car is running a OTS stage 2 tune from cobb and has a bigger tmic, catted downpipe, stock bov, stock intake. When I unplug the MAF the idle goes back to 14.7. I bought a new denso MAF and that did not fix my issue. I tried checking everywhere for vacuum leaks and I cant seem to find any. There is also a CEL for a misfire on all 4 cyls and fuel system lean. Once the car is moving everything is normal, afrs read between 13 and 15 cruising. Any ideas? I'm at a loss. Car is a 2002 with 132k
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11-01-2019, 03:07 PM | #2 |
Scooby Specialist
Member#: 395793
Join Date: Jul 2014
Chapter/Region:
Tri-State
Location: SLC and Lake Placid
Vehicle:2005 92x Aero Beige |
Did you reset the computer after installing the new MAF? Do you mean Prosport? Not passport. Might need to recalibrate the O2 sensor for it or replace it if it's old.
As for the misfire. Have you checked your plugs and coils? Not that all 4 typically go at once. Crank position sensor can cause misfire codes. And lightened flywheels are notorious for it. Especially if they are combined with a light crank pulley. |
11-01-2019, 03:18 PM | #3 | |
Scooby Newbie
Member#: 507940
Join Date: Nov 2019
Chapter/Region:
MWSOC
Location: WI
Vehicle:2002 wrx white |
Quote:
And the misfire, I'm pretty sure that its caused by the lean idle, its very lopey and rough at idle but instantly smooths out once driving. |
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11-01-2019, 03:35 PM | #4 | |
Scooby Newbie
Member#: 479655
Join Date: Dec 2017
Location: Omaha, Ne
Vehicle:2020 Impreza wrx CWP |
Quote:
After my Jdm swap on an 02wrx I had very similar issues. I replaced front o2, maf. Fuel filter.(none worked) Replaced injectors and fuel pressure regulator. This fixed the issue. I had the same symptoms. Also I would check your IACV this might be the issue for the looping idle(possibly). Although, a boost leak could create similar symptoms. Hope this helps |
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11-01-2019, 03:51 PM | #5 | |
Scooby Newbie
Member#: 507940
Join Date: Nov 2019
Chapter/Region:
MWSOC
Location: WI
Vehicle:2002 wrx white |
Just went and reset the ECU and went for a spirited drive. No dice, still idles lean. And yes it is a "prosport" afr, my bad lol.
Quote:
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11-01-2019, 07:25 PM | #6 | |
Scooby Newbie
Member#: 479655
Join Date: Dec 2017
Location: Omaha, Ne
Vehicle:2020 Impreza wrx CWP |
Quote:
Also what’s weird is when you unplugged your maf your car ran still...? When I did that my car turned off immediately. Which ruled out the maf in my case. But replaced anyways. My AFRs were loopy, jumping from low 13s to high 15s and occasional 17ish. When the FPR was replaced it fixed the idle AFRs. My injectors were a culprit of high af learning values and long cranks. Look into why your car would still run with MAF unplugged. And go from there.(if I’m reading your post correctly)? I’m not familiar with Prosport? Is that a afr gauge? |
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11-01-2019, 07:55 PM | #7 | |
Scooby Newbie
Member#: 507940
Join Date: Nov 2019
Chapter/Region:
MWSOC
Location: WI
Vehicle:2002 wrx white |
Quote:
And yeah, prosport is a brand of afr gauge. It reads constant 17 afr and the car sounds cammed/lopey at idle and shakes a lot. The second I start moving its fine and the afrs are what id suspect to be normal. Car doesn't take long to crank, you turn the key and it starts right up. |
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11-07-2019, 10:11 AM | #8 |
Scooby Specialist
Member#: 29292
Join Date: Nov 2002
Chapter/Region:
SCIC
Location: Orange County CA
Vehicle:2004 WRX wagon silver |
so what you want to do is unmarriy the cobb and see what your afrs are on the gauge, I had a prosport afr and that thing was a pos. I dont know what it is about their gauge but it always read differently, cant remeber if it was high or low but it was one or the other. So yeah honestly I dont think the car would run on a 17:1 afr to be honest.
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11-07-2019, 02:10 PM | #9 |
Scooby Newbie
Member#: 504375
Join Date: Jul 2019
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Unplug your O2 sensor - if the issue goes away that’s your problem
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