My rex is throwing the same P0102 code as yours is. My Greddy E-manage is the reason for it. It modifies the MAF sensor signal to adjust for injector size and fuel, just as your S-AFC does (and Im sure you know that). My mechanic and Sube dealer told me not to worry about it at all, and so far I havent had any perfomance problems. As for your misfires, I dont think they would be from your uppipe, unless its causing a lean condition in conjunction with your S-AFC. I have an uppipe as well and it hasn't caused any misfires. Try taking out your S-AFC & resistor and reset your ECU (if you haven't done so already). Dont give up and sell your car...these problems can be fixed. Good luck!

 

Yeah, take out the resistor as well, reset your ECU and see what happens. Keep in touch, Im curious to see if things work out for you.

 

I had numerous reports of people getting major misfire codes after installing lightened flywheels. That happens due to the increased noise that the car's engine/tranny make after that.

It is very possible that your uppipe making your car loud trips the knock sensor making it think you got misfire.

 

Yes. If the ECU "hears" a misfire for an extended period of time, then it puts the car into limp mode. Just like if you got a real misfire. This resistor mod... you are talking about an EGT resistor, right? The 2.2k ohm 1/4 watt resistor, I'm assuming. Check out the picture below. When you installed the resistor, did you form it like this?
If not, try it. You may not be making a circuit in the EGT sensor cable. Just a thought, though.

 

PM'd you, but to answer here:
go ahead and switch to the 1/4 watt (they're cheap!). Also, the wire is pretty rigid, so when you bend the loop into it, it makes it a bit springy. This help it stay in the sensor cable slot. Works great for me.

 

hey guys,
I have the same problem, I own a 2002 wrex and had a bad history with it. Its a long story so please bear with me. When I purchased the car from an action with minimal damage and the world was roses and peaches, afterall I did own a wrex. Then as I got it and fixed the damage I noticed a blinking cell. I thought nothing of it untill I read that it means to turn the car off or else. I said "oh crap!!" because I already drove it for a couple hundred of miles. When one purchases a car off the action lot and it is considered salvadged the dealer wants nothnig to do with you so i had to do everything the hard way. I started with an electrician. He figured out that I had 8 codes 4 of which are for the o2 sensors and the rest are misfires and a camshaft position center code. I was curious because I had put the car back to stock exhaust uppipe and all in order to pass smog and I shouldnt of had those o2 codes. THen the electrician climbed under the dash and messed with some type of plugs that the odb2 reader hooks up to, the cel stopped blinking. He told me that there were different plugs for different devices that read the cars system or something like that and he left the wrong one on. So he reset the cel and told me to go on my marry way and call him if the cel comes back. So I drive home feeling all warm and fuzzy inside untill the cel appears. So instead of calling the guy I go to autozone and rent the obd2 tester and read the misfire codes and the camshaft position code. I start to worry. I give the electrician a call and he tells me that the camshaft position code would go on if the timing was replaced and put on a tooth off. With no delay I take the car to the mechanic and he cheks my timing only to find out that it is perfect. Later on that day I go to the electrician and he checks the codes again. To my surprise I get another code, p0107 if i recall correctly, the car is running lean. So he goes and unhooks the MAF sensor and the car is running perfect no misfires or anything. He tells me that my MAF sensor is bad and buy a new one. I call the dealer only to find out that it costs $279. I go on ebay and find one for $90 and buy it. I get the new sensor and put it and to my surprisethe car is misfiring like a mo fo, the engine is shaking out of control. I disconnect the sesor and everything is fine. I get tired of going back and forth between mechanics and electricians and giving them money for nothing so I go to the guys that deal with it all the time. I arrive in the morning and tell them my story and problem, within minutes of looking over my car they tell me that the car had a piggy back chip that was removed and the wiring to the computer was jacked up so they go on and fix it and after I pay them $227 they tell me that I should pass smog and everything should be fine. The car did run good but felt for some reason a little shaky, I thought nothing of it. The next morning after I start the car I get the dreaded cel. I looked confused because I thought the problem was fixed. I grab my handy obd2 tester only to find out that cylinders 1,3, and 4 wre misfiring. I have a crancshaft pulley on and nothing else. I think that it would be the culprit in all of this but only time and the guys in the subaru place to tell me. I would grately appreciate any help. Im thinking of reflashing the ecu to make it compatible with the mods that Im putting on it (uppipe, downtime, and a 3" exhaust) to get more juice out of it and hopefully fix the misfires.

 

Nice first post!!!

 

what a way to hijack a thread.

 

EDIT: Damn, this thread is old. I replied thinking this was someone with a new problem.