2002 Subaru Forester stutters on take off, will backfire then suddenly engage and shoot forward

Asked by May 28, 2018 at 05:46 PM about the 2002 Subaru Forester

Question type: Maintenance & Repair

Have had IAT sensor replaced (showed code), then fuel filter, spark plug wires
rreplaced, auto trans flush, oil change and new filter plus general maintenance
service on 137K. Still not running right. Much hesitation and rough running.

7 Answers


Check for cracked coil. Did you flush the AT (wrong!) or simply drain and refill (right!)? Try spray-cleaning throttle body and assuring vacuum hoses, pcv and MAF sensor areas are not leaking vacuum.

1 people found this helpful.

Could problem have to do with fuel injectores? Any use to add Fuel Injector Cleaner?


Go ahead and use a fuel injector cleaner. It may or may not fix the problem but you are only spending $10 or so.


I noticed that you did not mention new spark plugs. Did you replace them?

No - they had recently been replaced about 4K ago.


Swap out that coil! Used ones are cheap, and it's an easy job.

Finally - It turned out to be the AFS - Air/Fuel sensor. Repalced and car works just fine, with more pep and, more importanly, no more stuttering!! Yay! Thanks for your info. C

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