O2 sensor diagnosis
11-16-2016, 12:29 PM
#1
Rennlist Member
Thread Starter
O2 sensor diagnosis
Hi Guys,
I have noticed that my car has been running rich, in spite of checking and adjusting the usual things (AFM, Temp 2, throttle switches, etc.). It's been running 12.5-13 at idle and cruise. It's about the same with or without my NB O2 sensor attached, however it oscillates slightly when connected. It occurred to me that this might be a bad O2 sensor, so I connected the simulated NB signal from my WB O2 sensor to the car, and now it oscillates around 14.5. It now behaves well at all throttle demands.
I'm tempted to just leave it like this. Does that seem to indicate a bad primary O2 sensor (replaced maybe 5 years ago)?
Thanks,
Dave
I have noticed that my car has been running rich, in spite of checking and adjusting the usual things (AFM, Temp 2, throttle switches, etc.). It's been running 12.5-13 at idle and cruise. It's about the same with or without my NB O2 sensor attached, however it oscillates slightly when connected. It occurred to me that this might be a bad O2 sensor, so I connected the simulated NB signal from my WB O2 sensor to the car, and now it oscillates around 14.5. It now behaves well at all throttle demands.
I'm tempted to just leave it like this. Does that seem to indicate a bad primary O2 sensor (replaced maybe 5 years ago)?
Thanks,
Dave
11-16-2016, 11:17 PM
#2
Rennlist Member
Thread Starter
Well after reading some old Rennlist posts, the consensus was that simulated NB from a WB O2 sensor may work, but might not be as durable as a designated stock NB O2 to run the fuel injection. Since I have a y-pipe and two O2 sensors anyway, I've ordered a new Bosch NB. I'll have a WB on the DS and a NB on the PS for the fuel injection ECU. I will of course run a comparison and report.
Thanks,
Dave
Thanks,
Dave
11-18-2016, 07:09 PM
#3
Rennlist Member
Thread Starter
Hi again,
Well you guys are probably wondering why I didn't check the voltage on my original NB O2 sensor. My multimeter died, and I just got a new one. So my O2 sensor gave me 0.0 volts. That tells the Ljet brain that I'm too lean, so it tries to correct, and gives my an AFR of 12-13. The simulated signal for that is 0.8-0.9 volts at that AFR.
Anyway I ordered a new Bosch O2 sensor, direct fit. Hopefully that will put me back on an even keel, and I won't depend on the simulated NB signal from my WB O2 sensor.
Thanks,
Dave
Well you guys are probably wondering why I didn't check the voltage on my original NB O2 sensor. My multimeter died, and I just got a new one. So my O2 sensor gave me 0.0 volts. That tells the Ljet brain that I'm too lean, so it tries to correct, and gives my an AFR of 12-13. The simulated signal for that is 0.8-0.9 volts at that AFR.
Anyway I ordered a new Bosch O2 sensor, direct fit. Hopefully that will put me back on an even keel, and I won't depend on the simulated NB signal from my WB O2 sensor.
Thanks,
Dave
Last edited by j.kenzie@sbcglobal.net; 11-19-2016 at 08:24 AM.
11-18-2016, 09:41 PM
#4
Rennlist Member
Thread Starter
Well it sounded like a nice story with a consistent conclusion. I went and put in my new Bosch, exact fit replacement O2 sensor. Guess what? No voltage output from it either. Same rich condition,when I used it to run my Ljet. I wrapped it up for return. I used a plug for my exhaust bung, and re-connected my simulated NB signal from my WB O2 sensor. It actually runs pretty well when rich, but it stinks of HC.
I'm going to leave it at idle AFR of 14.0-14.5. I even did an open air cal of the WB. It was fine.
The open loop AFR's drop to 12-13 under heavy throttle and/or boost, so I'm pretty happy like this for now.
Dave
I'm going to leave it at idle AFR of 14.0-14.5. I even did an open air cal of the WB. It was fine.
The open loop AFR's drop to 12-13 under heavy throttle and/or boost, so I'm pretty happy like this for now.
Dave