so i just got this 05 wrx a few weeks back and took it on a 1800 mile trip last week. the engine started running a little harder and just sounds pretty tight. i know that something has been done with the tuning before i bought it and i figured maybe that was it. it also started backfiring too. its just running a bit harder then when i bought it. any ideas as to why? is it the tuning or what is causing the backfiring?
That means it's running rich. What mods are done? Blow-off valves are known to cause backfiring. I wouldn't leave a tune on the car that I didn't know what was done. When I got my car it already had an AccessPort married to it, but I didn't know what tune it was for sure. It's better to be safe than sorry. How do you know the car has/had a tune on it? Did the previous owner tell you? If it has nothing to do with the tune I'd say it's related to the spark plugs/coil packs. Those are the parts that would cause a rich condition and backfire also.
Where do you come up with this stuff? could be an exhaust leak, could definitely be a bov issue. I've had a small hose near the alternator come loose and cause rough running and back firing. As simple to fix as connecting it again. Any codes?
355 awhp fp green six speed wagon in Corvette Atomic Orange
Lol! I know right? I even googled it and didn't find anything.
Afterfire is the result of unburn fuel in the exhaust heating up.
Backfire is exactly the opposite. Backwards firing of the intake charge. If its out your tailpipe, its not backfire. A backfire is when the air/fuel mixture ignites in the intake tract before entering the cylinder. It is an explosion that travels up out of the heads, through the intake manifold, and in our cars would have to then travel through the intercooler, back through the turbo and out the intake. If your car actually did this, I would expect that, at a minimum, you would be replacing the turbo, possibly the intercooler, the MAF, and many of the plastic/rubber hoses. If you are on the stock intake, there is a good chance you would blow the lid off the box. You would also stand a chance of blowing the intake valve open and spitting a retainer, sending the valve into the top of the piston.
I was originally just prodding. The OP clearly meant he was afterfiring.