Alright well I bought a 2005 WRX from a friend who needed some money, and he had put on a cat-back exhaust, short ram air intake, XS power headers and up pipe, a HKS SSQV BOV, and no tuning. There is a CEL on right now and I hooked up my scan tool, and it was showing a p0133 p0171 and a p0420. I just drove it after clearing and installing the non-fouler things and the p0171 came back and and p0420 is pending. Would a faulty O2 sensor be causing these codes, or the simple fact that it needs a tune?
From what I can tell, both o2 sensors are shot! The po133 is malfunction on the front o2. That causes p0171, fuel trim issue, and the catalytic converter inefficiency of the p0420 is just icing on the cake, lol. You need more than a tune. I would suggest a front and rear o2 sensor and then a tune after that. The rear is not 100% but the front is definitely in need of being replaced. There are some great tuners on here, Doug and Scott at Topspeed and Dan at Battleground. I am sure either shop could get you taken care of if you don't feel comfortable with an off the shelf solution or tuning yourself. Where are you located? It might help if someone took a look at the car to see exactly what is on it. If they went to all that trouble it PROBABLY has a downpipe too. If it is basically a stage 2 car (turbo back exhaust, not cat back, and a up pipe) Then you could probably get away with Cobb stage 2 OTS map until you can get it professionally tuned. I would attempt to find out if he still has the stock air box and throw it back in until you can get a tune specifically for your car. Intakes can be dangerous on these cars with out tuning. Bottom line, the car is not in good shape right now and it is not healthy to drive it like that.
If us a call. Schedule an appointment. We'd be happy to diagnose it for you. Tray M TopSpeed Inc. 866-94SPEED
Thanks for the help. I live around the Kennesaw area pretty close to Atlanta, but I do know for a fact that it doesn't have a down pipe. I've been under the car and have see first hand.
Well, it has one it just may be a stocker, lol. Before getting tuned, throw one of those on there! I would sell you mine, but I am not QUITE done with it...couple more months and someone can be the lucky recipient of a very nice 4" turboxs bellmouth!
Get some CEL deletes and f' the O2 sensors. Get rid of the BOV, which is probably causing the fuel issues. The CEL is probably from a removal of cat in the up thats why the cat is inefficient. CEL delete is less than $20 and it only requires a few wire splicing on the O2 sensor in the intermediate pipe. I bet you clear it after those two things and everything will be fine.
The car RUNS based on the front O2 sensor. That's what does ALL the fuel trimming, INCLUDING at WOT. You *MUST* have a properly operating front O2 sensor. If the rear O2 is not functioning right it will hurt your gas mileage 3-4 mpg as it does "rear-o2-enrichment." Siegel
Well yeah it has a DP but it's stock. So, your saying put an aftermarket DP on it, new front O2 sensor, and remove the BOV? Does anyone know where to get a stock BPV I've tried to find one, but it seems like they're hard to come by. Also are those headers/up-pipe any good? Or does it really matter? Oh and where should i get an O2 sensor from? Should I go with stock, or will those universal ones work?
I suggest a real Subaru front O2. From your friendly local Subaru dealer Or us, I think we've got one in stock. I would also put the stock headers back on. Sell the aftermarket headers and get a DP. Siegel
Is there a down side to aftermarket headers on the 2.0L? Or did you suggest that b/c he doesnt have a DP and the $$ are better spent there?