I have a 98 rs with an 06 wrx engine with a vf48 protuned. The car was running great until my last full up. I didnt have my accessport at the time but i did a pull a few minutes after and thought i heard a bang shifting from 2nd to 3rd. I got home got my accessport and when for a drive everything was fine. I didtwo pulls and nothing so i thought i was just hearing things. Filled up again this morning did a pull 2/3. BANG!!!! Cant get into gear. Thought trans blew but I managed to finesse it into gear drive off. I shifted up and it was hard to get in but it did. Got home tried putting it into every gear and all of the them hard to get in.
Jacked the car up check everything over found nothing. I drained the trans oil found some small shavings. Filled it up with new and it works fine. Go out for a drive with the accessport and i feel the car pulls much harder now then before and when i let off the gas it jerks violently. My steering wheel is now shaking when braking above 60mph. I kept getting fineknock learn and feedback of -1.4 to -2.8 during pulls. Im also hitting .5 to 1 psi higher.
I switched to the safe map and i get no more knocking but its still jerks when lifting off throttle above 5.5k below that is fine. I reving the engine while stop and i didnt here any knocking from the front but if i hold at 3k rpm theres some popping coming from muffler area. I dont know if its from the baffle rattling or the muffler possibly hidden in the heat shield. I don't remember it happening before.
With the main map i notice the idle afr is 15 :1 instead of 14.6-8 like it was before the gas fill up the safe map is normal 14.7. Could bad gas cause it to run leaner? Could a sticking caliper cause the jerking when letting off the throttle?