twitch

My 02 wrx has a slight shake n hesitation under light load but when in wot its perfectly fine. Had a misfire cylinder 4 so I changed the plugs. Haven't had a cel since. The car is bone stock. I have a few ideas but I don't want to throw money into Parts if there not the problem. I was thinking fuel filter maybe a coil but I'm not throwing codes maybe maf acting up. I understand snow tires don't help but I just got the car n saving up for new tires. Any ideas at where to look at or if anyone has had the same issue and figured it out would be helpful

Garrett93

Post this on NASIOC if you haven't already.

Irhodes14

I had a similar issue on my 03. Try cleaning the crank sensor.

Fabrik8

You should replace the fuel filter and do the rest of the maintenance before going any further. Clean the MAF and see what happens. That's especially important if you're using any kind of oiled reusable air filter. I doubt it's a fuel filter problem though, because the problem should get worse as load and/or RPM increases (because of the extra fuel flow). Coils are a possibility too, because a problem at low ignition duty cycle can clear up at higher ignition duty cycle, and the other way around. That's a hard thing to diagnose without having specialized equipment, usually replacing parts is the easy thing to do. I'd save that until later once you check the more likely suspects first. Same thing with O2 sensors.