AF Correction +25% Pumping Brakes

BlueSubeDude · 12-29-2012, 06:18 PM

My random misfire is driving me crazy...

Symptoms:
I have an inconsistent misfire on cylinder 1. This usually happens after I pull out of the driveway and drive a few blocks to a stop light. When I approach the light I notice that the engine idles roughly and then settles out after a while. At this point I get the CEL for Cylinder 1 misfire. It doesn't happen all the time.

Observations:
I notice that my car idles smoothly when the car is cold (open loop) and when the car is completely warmed up I don't have the problem. It usually happens about 3 minutes after I start driving out of the driveway. I used the AP to look at the AF Correction 1 and have noticed that when I'm on the brake the AF Correction goes above 10%. As a test, I pumped the brakes and found that the AF goes all the way up to +25% and the engine rpms change. At idle the AF Correction hovers +/-8%.

Car/Mods:
2006 WRX Stock with K&N Filter. The Airbox has broken tabs so I tied the box down with rope (been running like this for a couple of years). Cobb Stage 1 Map (does the same on stock map). I also have a small evap leak somewhere, but it's been fine for over a year (p0442). I recently changed plugs NGK iridiums, 0.03" gap. Compression hovered about 150 +/-2% on every cylinder.

What do you guys/gals think?

12-29-2012, 06:18 PM	#1
BlueSubeDude Scooby Newbie Member#: 172977 Join Date: Feb 2008 Location: Northern California Vehicle: 2006 WRX TR	AF Correction +25% Pumping Brakes My random misfire is driving me crazy... Symptoms: I have an inconsistent misfire on cylinder 1. This usually happens after I pull out of the driveway and drive a few blocks to a stop light. When I approach the light I notice that the engine idles roughly and then settles out after a while. At this point I get the CEL for Cylinder 1 misfire. It doesn't happen all the time. Observations: I notice that my car idles smoothly when the car is cold (open loop) and when the car is completely warmed up I don't have the problem. It usually happens about 3 minutes after I start driving out of the driveway. I used the AP to look at the AF Correction 1 and have noticed that when I'm on the brake the AF Correction goes above 10%. As a test, I pumped the brakes and found that the AF goes all the way up to +25% and the engine rpms change. At idle the AF Correction hovers +/-8%. Car/Mods: 2006 WRX Stock with K&N Filter. The Airbox has broken tabs so I tied the box down with rope (been running like this for a couple of years). Cobb Stage 1 Map (does the same on stock map). I also have a small evap leak somewhere, but it's been fine for over a year (p0442). I recently changed plugs NGK iridiums, 0.03" gap. Compression hovered about 150 +/-2% on every cylinder. What do you guys/gals think?

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