First datalog / HEGO2 not working?

Discussion in '1994 - 1995 Specific Tech' started by cjrpony, Mar 21, 2010.

  1. Well I tried my first datalog with the Tweecer RT today. Everything seemed to work ok with the Tweecer/CalCon and I got a couple of 2 minute runs logged. Mostly just idle with a few seconds of 2-3K RPM. The car has been running rich so I looked at the HEGO's to see what they were saying. HEGO1 seemed to be reading normally, bouncing up and down around .5 but HEGO2 did not appear to be doing anything. It was staying at the bottom of the scale. Voltage was almost 0 on this sensor. This would indicate very lean to the computer and cause it enrich the fuel to that bank, correct? I hooked up my LM-1 wideband to that bank and it was reading around 12.5 and would drop to about 10.5-11.0 when I gave it some gas. KarmF2 was reading 11.3 which means the computer is commanding more fuel, correct?

    So I am guessing that the O2 sensor is not working or not working correctly. I am looking for some feedback on if I am analyzing this correctly or am I missing something. I don't have much more time today to play with the car, so tommorrow I think I will check the connections on the O2 sensors and maybe swap them to see if the problem switches to the other side. I will probably just break down and get a couple new O2 sensors anyway.
  2. either that, or i suppose it is possible that there might be an exhaust leak such that there is air getting INTO the exhaust and then going through the sensor. but probably the more likely case would be exhaust coming out, not air getting in. then again, if exhaust can get out, then some air might also get in ... :shrug:

    is the wideband before or after the stock O2 sensor? might there be a leak there?

    but i'm with you ... probably the sensor is going bad. you might try swapping the sensors to see if the readings switch to the other bank.
  3. Thanks for the reply. The wideband is after the O2 sensors, about 6 inches before the crossover tube in the O/R H pipe. I am going to try swapping the sensors, then I can eliminate an exhaust leak or faulty harness if the problem moves to the other side.
  4. After getting the O2 sensor out, it looks like it is bad. 3 of the 4 wires have bare spots on them and the threads on the sensor and the bung are both shot. So now I have 2 new sensors coming and 2 new bungs. Now I have to pull the H-pipe again and install the new bungs and put it all back together again.:mad: Oh, well, hopefully it will run better with the new sensors in it.
  5. one more reason why datalogging is a great tool. how much longer would it have taken to figure out that there was a problem there without the hard data that the log gave you to identify it? the log made it pretty obvious.