Recently I purchased a pre-owned 2002 WRX that appeared to be in decent condition at 120k miles. Well, as always with used cars, things are not as they seem. After a few months it became apparent that the vehicle was not taken care of at all, and required quite a bit of work. After replacing almost the entire front end of the vehicle, suspension, clutch, air intake, and leaking radiator, I noticed that the CEL was continuously on, reporting an 02 sensor issue and misfires on all four cylinders. While troubleshooting this issue, I discovered that the previous owner had welded a catless downpipe into the car. Now, for the price I figured some maintenance would be expected, but I'm beginning to run out of expertise in dealing with some of these issues, and although I really want to love this car, its becoming difficult. Just today I seemed to have developed another exhaust issue, and suddenly the vehicle is EXTREMELY loud.
I apologize in advance, but I have spent the last few months scouring this forum to repair my subie to a good condition, and I thank all of you for your contributions! But even after following stickies and others I have not found all of the fixes I need in order to properly care for the poor WRX I bought. I beseech you, can you help point me in the right direction?
1. Misfires on all four cylinders: After checking through the misfire thread I ran all of the fixes suggested with no luck. Now I'm no car expert, in fact I know very little, but I'm aware that the timing on a WRX should be addressed at around 100k miles or so. The previous owner claims to have had it done third party, but is it possible that could cause the problem?
2. Constant O2 CEL due to a catless downpipe: As far as I can tell, there are a few options to fix this, from replacing the welded on downpipe, to remapping the ecu to ignore this error. What do you suggest as a cost effective solution that benefits the cars performance?
3. Sudden increase in noise: I feel like there could be an exhaust leak somewhere or possibly issues with the muffler. During the drive to work today the car was just suddenly incredibly loud, growling all the way down the road. Kind of sounds similar to some of those modders who put crazy exhaust systems on their cars, or even remove mufflers. Any pointers or suggestions on where to start troubleshooting?
EDIT: I am now getting a severe drop off in power, the car drives incredibly slow. Any suggestions would be much appreciated :/
Thanks in advance for all of your time, be gentle, I'm new at this (and cars in general.. I'm a poor CS major) and I want to do it right. It just seems the previous owner to my WRX took things too rough and didn't bother to care for the car.