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Discussion Starter · #1 ·
I’m sure this has been asked a million times. My sisters 06 forester has a rough idle issue and occasional maybe 50% of the time a hesitation on take off.
Codes now coming up cylinder 2 misfire and cylinder 4 misfire.
I’ve done an idle reset and cleaned the MAF sensor. The fuel pump and strainer have been replaced.
Fuel filter is approx 6 months old.
Any ideas before we take it to Subaru would be appreciated

2009 Forester Automatic
14 Posts
Next i would check plugs and wires, after that try the O2 sensor. I also FINALLY stumbled upon this TSB, which seems to be helping with my hesitation issues, but is not back to perfect for my car. I also have not gotten to properly perform this procedure through and through, because of traffic. (i am going to do plugs and wires soon as well)

Whenever I searched for information on this, most of the stuff was about how throttle lag occurred because of the fly-by-wire system, and that there's not much to do about it short of remapping the ECU (which I know nothing about and is way beyond my comfort level). I figured I'd just have to live with it.

But(!) the tech actually found an obscure TSB, most of which I've transcribed here:
#11-77-05; date, 09/08/05
Applicability: 2006 Forester and Impreza 2.5L SOHC, non-turbo vehicles

During your road test when performing PDI, if you notice hesitation from a standing start after engine is warmed up, there is the possibility that the ignition timing learning was not finished completely. With that condition you would experience hesitation during acceleration due to temporary engine torque stopping when the valve lift of the variable valve lift mechanism is changed from Lo to Hi. The hesitation can be cured by performing the promotional learning method for the ignition timing.

AT vehicles (there are two methods, either may be used)

A. Method by Stall
1. Warm the engine up until the radiator fan comes on.
2. Engage the parking brake and fully depress the brake pedal, put the transmission in drive "D" range, then fully depress the throttle pedal for five seconds.
3. Put the transmission in neutral "N" range, let the engine cool down for at least five seconds.
4. Repeat steps 2 and 3, four times.

B. Method by driving on road
1. Warm the engine up until the radiator fan comes on.
2. Put the transmission in 2nd gear and accelerate from 0 mph, wide open throttle, to 35 mph (about 3,200 rpm)
3. Repeat step 2, five times

MT vehicles
1. Warm the engine up until the radiator fan comes on.
2. Put the transmission in 3rd gear, then accelerate from 25 mph (about 2,000 rpm) with wide open throttle to 40 mph (about 3,200 rpm)
3. Repeat step 2, five times. "
Hope this helps!
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