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Old 05-15-2021, 10:07 PM   #1
ilovedemhotrides
Scooby Newbie
 
Member#: 326147
Join Date: Jul 2012
Location: Philly
Vehicle:
2004 STI
wrb

Default Datalog shows 13-20 AFR, with no A/F correction for 3 seconds

Long story short, the car is idling bad, and when revved shakes the car. I've replaced the 02, cleaned the MAF, boost leak tested the car, changed the sparkplugs (passenger 2 fouled from running rich), and still haven't found the issue.

I took some datalogs and was trying to teach myself what everything is. I noticed an anomaly that I can't explain.

If you look at rows 204 - 230 (3 second time span), the AFR fluctuates from 13 - 20 with the A/F correction being 0. This sticks out because why would it just stop correcting for these 3 seconds?

I am new to looking at logs, but I don't know why this would be happening. If the AFR is fluctuating this much, why would the correction be 0. Also odd it lasted for approx 3 seconds, and then started to correct again.

Look at rows 204-230 specifically for this issue.
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Old 05-15-2021, 11:07 PM   #2
subaru_gc8
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Member#: 29292
Join Date: Nov 2002
Chapter/Region: SCIC
Location: Orange County CA
Vehicle:
2004 WRX wagon
silver

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well when you take your foot off the accelerator theres a fuel cut that happens to a certain rpm. that is why you are hitting the 20's if your car is shaking you have to check out the roughness that will tell you what's going on
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Old 05-16-2021, 09:01 PM   #3
akritzer
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Join Date: Feb 2020
Chapter/Region: MAIC
Location: NOVA
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2013 WRX Hatch

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Do you have a check engine light on?

Are you sure you're firing on all four cylinders?

Does anything change when you unplug the front o2 or the MAF?
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Old 05-19-2021, 08:03 PM   #4
ilovedemhotrides
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Location: Philly
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2004 STI
wrb

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Quote:
Originally Posted by akritzer View Post
Do you have a check engine light on?

Are you sure you're firing on all four cylinders?

Does anything change when you unplug the front o2 or the MAF?


No CEL. When I unplug MAF, car runs bad still but runs a lot more rich
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