I'm not sure if I posted this in the right spot but here I go anyway.

 

I have a 2002 Subaru Forrester

 

Replaced o2 sensor about a year ago. No symptoms of a problem but the CEL light came on.

 

Six months ago while driving it started losing power unless giving it half throttle

 

Three months ago started hesitating and surging occasionally.

CEL came on reading knock sensor.

 

I replaced the knock sensor with cheap one from eBay

 

Engine continues to surge and hesitate

 

I replaced spark plugs and wires

 

1 month ago it stated back firing and shaking badly

 

I haven't driven it much since then

 

I took it into the super dealer and they couldn't find anything wrong with it. Connected to their diagnostics and told me nothing was showing up

 

Last week I got a code for misfire on cylinder 1 and 2

 

I replaced the coil pack with a used one, but nothing changed.

 

It misfires when engine is cold (it's winter now) and after letting it idle for at least 30 mins drives fine.

 

Should I check other sensors?

IAC?

MAP?

What is wrong with my subie? I'm so tired of this

Edited January 7, 201610 yr by Dneff85

first - suprised the dealer didn't find a stored code. In a new thread, ask for a mech recommendation near your city. Someone may know of a good independent shop.

 

when was the timing belt system last serviced? A skipped tooth can make a car run poorly. Other tune-up services in good shape? original plug wires could be a problem when moist with condensation/dew too. Or oil leaks into the plug tubes....

Edited January 7, 201610 yr by 1 Lucky Texan

could still be the knock sensor... find a know good one or buy a second one.  could also be the wires.... only use good NGK wires the cheap ones misfire.