Would installing a new rear o2 sensor mess with the fuel trims? I had the rear one go bad and now I am having some weird fuel trims...like running real rich at idle since installing it. Weirdest thing I have seen. I did not think that the rear o2 really had that much to do with the immediate fuel trims?
I mean it idles better now...but it is squirting in a ton of fuel....the map is calling for 14.7 and it is adding fuel in the STFT making it go down to like 13.5...really odd. I am thinking my front must be on its way out or something. Either that or when I was first making my E85 map and using the old rear sensor it may have messed with the tune, because as soon as I installed the new rear, everything has been off.
when one is bad/not present for class it'll target 13.5:1. SOOOOOOO........where did you get this 'new' one?
local parts store....brand new walker sensor...they didn't have denso for the rear. I did order a new denso for the front as I figured it would probably need to be replaced shortly as well. Something else I noticed that is out of wack...the front is reading WAY off all of the sudden some times...it's not all the time, but it is not behaving the way it used to. The readings used to be pretty close to the wideband readings...now they are pretty far off sometimes. Possible that the front is on it's way out as well and causing the weird readings? I mean 125k is a lot...heard they usually start going around 100k miles.
SUBARU parts from a SUBARU dealer works wonders... Aftermarket parts such as sensors I would NEVER NEVER NEVER EVER NEVER use. Been there and done that. Front A/F sensor: 22641AA042 Rear O2 sensor: 22690AA520 Here: http://www.trademotion.com/partlocator/index.cfm?siteid=214725 And then you get cheap prices such as $251.92 for both plus shipping. Seriously, until you put SUBARU sensors back in the car, I cant help you. I cant count how many times I've been working on one that had non-SUBARU A/F and O2 sensors in it and the crappy NON-SUBARU sensors were to blame. Same for MAF, MAP, cam/crank sensors.
Are those part numbers the same for the STi? I'm guessing that is where my fuel issue is too. I cleaned the MAF and that didn't make a differeat at all. Front O2 is two years old. The rear one has been twisted several times to the point the wires could be messed up internally. Might be a good place to check next. Mike (crash) wanna do a data log and see what's going on? I'm free tomorrow. Mike K. We need to hook up too, PM me when you want to meet again.
Yikes!!! What's up with those crazy shiipping charges for UPS ground? I got quoted $43 to ship the MAF, front and rear o2. They can all fit in one box and should cost roughly $15-$20ish. Can they use USPS?
Will I actually checked into the source of parts and the sensor is a repackaged denso sensor...same as the stock subaru sensor. I am going to throw in the new front Denso when it gets here and see what happens. The only other thing I can think of is that there is a short somewhere in the wire.
I have been logging it, and I know what it is doing, just not sure why. I am going to pull the specs on it and see what the manual says the testing procedures to go through for the sensor. If it is not up to par with what it should be per the subaru manual, then I will return it. Did you ever get that ROM off that ECU?
But is the sensor specifically *calibrated* for the SUBARU??????????????????? I'm willing to bet that the Denso sensor you have has multiple applications where as the SUBARU one only has ONE application, the 2002~2005 EJ205 USDM WRX.
Well, did some checking and saw that it was not reading when I logged with Romraider...st does not have a setting to monitor the rear ecu. With romraider I was able to see that the rear o2 was getting no signal what so ever...got under there and did some tracing of the signal wire and saw where it was frayed and grounding...a little time and the problem is fixed....AFTERMARKET sensor is working perfect and everything is back to normal. I know that stock parts work better sometimes will. And I am not doubting your experience...but in this case it IS the rear sensor and all I need it to do is work close to what the stocker does. It is getting a funky signal anyway with no cat to read after.