hey my CEL is on so i went to a shop and the hooked it up to the computer and the print out showed that there was a miss fire on cyc. 1 and 2 and a air leak problem just wondering if anyone has ran into this problem and how big of a problem this is. I drive a 02 a4 1.8t with stage 1 apr tuned. thanks for the help guys. i lent my car to my sis and she filled it up a couple time and didnt use 93oct. woundering if this could of fouled some of the plugs and thats how im getting a miss fire.

 

Is it still misfiring(running like crap)? If not its was probably caused by the low octane fuel causing a misfire. If it is still misfining try swaping coils, plugs, injectors to different cylinders and see if it follows them to the new cylinders. As for the vacuum leak it, check your vacuum lines for one that is unhooked or leaking. Also check to make sure all your turbo hoses are still connected securely.