RSPSupra97
08-10-2005, 08:46 PM
Finally making my first post over here, most of you guys know me as Rocky28072 over on SF.
Anyway, I've had my car na-t for quite some time now (30K+ miles) and never had any major issues of sorts. I know a lot of people have had trouble with obd2 na-t and tuning, but I've seemed to be fairly lucky. I have a wideband in the car and always have gotten a good wot tune on the car and has been reasonable under partial throttle.
Recently, I had begun to notice how the car was fighting my fuel settings and trying to dump in too much fuel after driving just a few miles. I havent changed any part of my setup nor the boost level that I daily drive on. Resetting the ecu and even the fuel maps in my vpc/safc combo would only fix the problem temporarily. Normally, cruising I see afr's in the 13-14:1 range and idle is about the same. It would be okay at first and then it was like the ecu was relearning some wrong settings and cruising afr's would dip in 11-12:1 and idle was worse at 10-11:1.
Now I have been only using 1 of the 3 stock o2 sensors present on the obd2 cars. I had both the extra manifold sensor and the 3rd cat sensor unplugged. Thus this would always throw a CEL after approx 1.5 miles of driving after resetting the ecu.
I figured the sensor I do use was going bad and decided over the weekend to finally wire up my 3rd sensor simulator (casper version) and also try and cut and splice in the blue signal wire from the unused manifold sensor into the sensor currently in my dp.
So I preceded to install both items and take the car for a drive and see what happens. Oddly enough, now the car (on the same fuel maps/settings) idles between a perfect 14.7:1 and a very lean 16.5:1. Cruising afr's have also changed a lot and I'm now seeing 14-16:1 cruising. Also the CEL stayed off! I thought this was great at first but problems have arisen. The car throws a CEL now after about 15-20 miles of driving and watching the afr's, the ratios jump around quite dramatically on their own, anywhere from 13-15:1. I can even feel "surges" in the motor when the afr's are jumping around when I have constant pressure on the throttle. Also, sometimes the car will unexplicably go very very lean; almost to the point the engine wants to die (has stalled out on me a couple times). Oddly, I've also noticed that sometimes (not all the time) when I hit a bump or dip in the road, it makes my car go crazy lean! Afr's will jump up to 18-19:1 and the car struggles to run, but after a few seconds it settles back out! When I go partial throttle into boost now, afr's stay much too lean (14:1) and my egt's spike like crazy (750-800 C). As before with 1 sensor only, under partial load, afr's would drop to around 12:1 and thus keeping egt's much lower.
So now after being aggrivated by the new lean and erradic conditions my car is producing, I've ordered a new o2 sensor from Curt at Elmhurst and I'm going back to the way I had it setup with 1 sensor in the dp and having the other one unplugged. I am hoping the reason it was going so rich was a bad o2 sensor. Overall, it seemed to work better for me this way in the past. I'll just deal with throwing the CEL. If anyone has any explanations or reasons for such strange behavior, I'm open to suggestions. :sadwavey:
Anyway, I've had my car na-t for quite some time now (30K+ miles) and never had any major issues of sorts. I know a lot of people have had trouble with obd2 na-t and tuning, but I've seemed to be fairly lucky. I have a wideband in the car and always have gotten a good wot tune on the car and has been reasonable under partial throttle.
Recently, I had begun to notice how the car was fighting my fuel settings and trying to dump in too much fuel after driving just a few miles. I havent changed any part of my setup nor the boost level that I daily drive on. Resetting the ecu and even the fuel maps in my vpc/safc combo would only fix the problem temporarily. Normally, cruising I see afr's in the 13-14:1 range and idle is about the same. It would be okay at first and then it was like the ecu was relearning some wrong settings and cruising afr's would dip in 11-12:1 and idle was worse at 10-11:1.
Now I have been only using 1 of the 3 stock o2 sensors present on the obd2 cars. I had both the extra manifold sensor and the 3rd cat sensor unplugged. Thus this would always throw a CEL after approx 1.5 miles of driving after resetting the ecu.
I figured the sensor I do use was going bad and decided over the weekend to finally wire up my 3rd sensor simulator (casper version) and also try and cut and splice in the blue signal wire from the unused manifold sensor into the sensor currently in my dp.
So I preceded to install both items and take the car for a drive and see what happens. Oddly enough, now the car (on the same fuel maps/settings) idles between a perfect 14.7:1 and a very lean 16.5:1. Cruising afr's have also changed a lot and I'm now seeing 14-16:1 cruising. Also the CEL stayed off! I thought this was great at first but problems have arisen. The car throws a CEL now after about 15-20 miles of driving and watching the afr's, the ratios jump around quite dramatically on their own, anywhere from 13-15:1. I can even feel "surges" in the motor when the afr's are jumping around when I have constant pressure on the throttle. Also, sometimes the car will unexplicably go very very lean; almost to the point the engine wants to die (has stalled out on me a couple times). Oddly, I've also noticed that sometimes (not all the time) when I hit a bump or dip in the road, it makes my car go crazy lean! Afr's will jump up to 18-19:1 and the car struggles to run, but after a few seconds it settles back out! When I go partial throttle into boost now, afr's stay much too lean (14:1) and my egt's spike like crazy (750-800 C). As before with 1 sensor only, under partial load, afr's would drop to around 12:1 and thus keeping egt's much lower.
So now after being aggrivated by the new lean and erradic conditions my car is producing, I've ordered a new o2 sensor from Curt at Elmhurst and I'm going back to the way I had it setup with 1 sensor in the dp and having the other one unplugged. I am hoping the reason it was going so rich was a bad o2 sensor. Overall, it seemed to work better for me this way in the past. I'll just deal with throwing the CEL. If anyone has any explanations or reasons for such strange behavior, I'm open to suggestions. :sadwavey: