Ok so my girlfriend bought this car about 4 months ago. 1998 eclipse gs 5spd. 108k for 1200 bucks. no rust. needs a o2 front bank 1 sensor and a clutch. Get a used o2 sensor off a sitting car and rewired it (universal crap) Reset the ECU and the car ran great for about 20 miles or so then it tried to stall, rpms dropped quickly and then raised quickly about 2-4 seconds later to normal idle and a CEL appears reading P0171 or System too lean.

Any opinions. Car runs great. idles fine. lots of power. Smells a bit sometimes like gas.But everything seems good besides this new issue.

Car is stock other then a hps short ram and header to custom exhuast.


o2 sensor came off a 98 gs as well that was replaced not that long ago.

how do you know the used o2 you replaced it with is known good or not

also, note that the angle of upstream o2's need to face slightly away from the flow of exhaust gases. this prevents condensation which kills o2 sensors. Just and FYI

I cant be positive that its good, but i dont see how it could be bad, it canceled out the 02 sensel CEL and now it just reads the system too lean.

Im not sure on what you said about the angle..

I just matched the wires together. and had to pull the radiator out to get the damn thing in. tightened it up and reset the ecu, then it popped on after about 20 miles or less.

i dont know what else to check?

everyone on here states there car is doing something differently. could it be doing this if wd-40 got on it a little bit?

Originally posted by ryan95eclipse
Im not sure on what you said about the angle..

these rules apply to installation of all o2 sensors. Pages 5 and 9: http://www.vespalabs.org/@api/deki/files/615/=Bosch_lsu_info.pdf

Im not sure if i did that or not. i just pulled the radiator and screwed in the o2 sensor, it went right in and i tightened it with a wrench. twisted the wires together and taped em...etc

Originally posted by ryan95eclipse
twisted the wires together and taped em...etc

That may be your problem. Most O2 sensors use stainless steel wire, so you can't solder them with a soldering iron; instead, you should make your connections with with heat shrink crimp connectors. Just twisting the wires together probably isn't sufficient.

Okay ill try that first and see what happens. Ill be in a damn good mood if it fixes the problem. the girlfriend should be happy and it would be a good night. ;) haha ill try that either friday or saturday.

why did you buy a universal one? cutting wires just gives more of a chance for error.