04 Forester XT issue
 

Hi guys,

Just joined the forum as im now a proud owner of my first boxer :)

Wondering if anyone can help with an issue i am having and i have done multiple searches and cant find anything.

My car was idling weird almost stalling like missing when the thermo fan came on (no cel) did some research had the plugs replaced issue still there.
Led me to think it was the AFM i was told if you unplug the AFM and the car runs fine then thats the issue. So unplugged it car runs great. obviously has the cel but runs fine. so i bought a new afm from a guy on gumtree who sells aftermarket new ones. Reset the ecu and the car wouldnt drive under load or on boost (would splutter and blow black smoke hardcore) note didnt do this with old AFM. i contacted the guy and he sent me a new one. Will hit boost now and drive under load but high in the revs (like 5k) does the same thing splutters black smoke again and really struggles to idle. So im either thinking i need to get a OEM afm or it may be another issue that unplugging the AFM masks the problem. Could start eliminating the possibilitys replacing o2 sensors vac lines but thought someone might be able to help and save me spending bulk cash to find the issue.

Thanks in advance guys!

Sounds like a dudd AFM to me..

O2 senors only affect AFRs under closed loop situations, ie. idle and cruise

what mods does it have

Hey, sorry no mods at just catback exhaust