[Subarjeff]

I have a '02 Forester L, 2.5, 5 spd MT, 73k miles, I've had the car since new. The car has recently developed an intermitant hesitation that happens in the 1300 to 1800 rpm range...it happens with the clutch fully engaged, and generally more often when the car is fully warmed up. The engine pulls very smoothly and strongly from 2000 rpm up, and idle and just off idle is smooth, and I can't seem to get the engine to stumble reving it in neutral.

There is no CEL, and no codes in the ECM. Maintenence, (plugs, filters) is up to date. The knock sensor was replaced a year ago, and the plug wires 40k ago, (a connector on the OEM ones broke). I checked the coil terminals and cleaned them, with no improvment, and added a fuel additive (B-12) to eliminate water and clean the injectors. That provided a slight improvement in drivablity otherwise but didn't effect the hesitation. The battery has less than two years on it, and the car never fails to start on the first crank.

Any ideas??

Thanks,

Subarjeff

 

[funkymonkey1002]

How has gas mileage been? Does it happen more under load, such as going uphill at low RPM? Might want to consider replacing the front O2 sensor.

 

[Subarjeff]

Oops, I knew I forgot to mention something...The gas mileage hasn't changed, it's still an above the EPA rated 23+ mpg in town.

My first thought was the O2 sensor...what is the best way to test one? I have a repair manual on CD, but haven't found that section yet.