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Old 06-19-2023, 07:01 PM   #1
AndrewsBustedSubi
Scooby Newbie
 
Member#: 534640
Join Date: Jun 2023
Location: PA, WA
Vehicle:
2011 Wrx Hatch

Default Erratic idle A/F Rich then Lean

So ive been battling a erratic rough idle on my 2011 wrx. Noticing it doing it when it starts to get hot. Im going on 3,000 mile trip to Washington State soon and would love to iron this out.

Once it warms up my idle becomes erratic. A/F starts bouncing rich to lean. Before I reset my learning, I had a A/F Learning (correction???) of 4.68%. So, I smoke tested the system. Had a couple leaks. Leak at the turbo inlet, AOS hose going into the block by turbo, Bypass hose going into the turbo inlet hose. Leaks all fixed, reset ecu learning, gave it a try no difference. Then I unplugged MAF, idle was perfect. A/F was pegged at 14.7. Took it for a drive with MAF unplugged (stayed out of boost). A/F started bouncing rich to lean when I came to a stop and idled eventually it smoothed out within 14 on A/F ratio. So, I decided to buy a new Denso MAF, No difference. i don't know what's wrong with this pos. I guess my next step is replacing the wideband. I have zero leaks and no codes.
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Old 06-23-2023, 01:11 PM   #2
enduroxt
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Member#: 310796
Join Date: Feb 2012
Location: UT
Vehicle:
05 obxt

Default

Looks like you have a way to view live parameters. How many miles on your car?

What are you long term fuel trims at the moment?

Another thing to check is MAF wiring harness. On both of my cars, the wiring harness (particularly at the MAF connector) was having ground issues. How did I check for this? Had the car idle, took my phone running the BtSsm app, and moved/bent the MAF wires at the MAF connector one direction or another and stared at the ECU parameters. Right away, corrections were getting implemented. You could even hear the idle.

Another thing to check: have you been logging misfire count per cylinder? Do they all stay at zero during warm idle? Do check.
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Old 06-23-2023, 01:11 PM   #3
enduroxt
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Member#: 310796
Join Date: Feb 2012
Location: UT
Vehicle:
05 obxt

Default

Looks like you have a way to view live parameters. How many miles on your car?

What are you long term fuel trims at the moment?

Another thing to check is MAF wiring harness. On both of my cars, the wiring harness (particularly at the MAF connector) was having ground issues. How did I check for this? Had the car idle, took my phone running the BtSsm app, and moved/bent the MAF wires at the MAF connector one direction or another and stared at the ECU parameters. Right away, corrections were getting implemented. You could even hear the idle.

Another thing to check: have you been logging misfire count per cylinder? Do they all stay at zero during warm idle? Do check.
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Old 06-23-2023, 01:19 PM   #4
enduroxt
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Member#: 310796
Join Date: Feb 2012
Location: UT
Vehicle:
05 obxt

Default

Forgot to mention. Once I confirmed the issue was at the MAF connector (not the MAF itself), I purchased a MAF connector pig tail from iWire.
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Old 06-24-2023, 02:01 AM   #5
riksk
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Member#: 518114
Join Date: Aug 2020
Chapter/Region: International
Location: BR
Vehicle:
11 WRX
Satin White Pearl

Default

Quote:
Originally Posted by enduroxt View Post
Forgot to mention. Once I confirmed the issue was at the MAF connector (not the MAF itself), I purchased a MAF connector pig tail from iWire.

Yeah I had the exact same problem once.


https://forums.nasioc.com/forums/sho....php?t=2926997
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