220ksho
Gen I bias
Symptom: A subtle miss that progressed from “barely noticeable” to “nearly un-driveable”
Occurrence: Hard driving on racetrack, WOT to redline, over and over. i.e. Racing. Ran perfectly for about an hour, then the first miss was felt. The subtle miss slowly progressed to a constant stumble under any load, and an inability to accelerate.
Facts: - Car – ‘89 w/ 100k. X2J computer. Stock except K&N and gutted cats. Cruise & AC removed.
-Error code: 176 – Oxygen sensor not switching – system is or was lean Left or Front HO2S – Fuel Control.
-This car is an ’89, so there was no MIL at the time. (I have since added one)
-After the race, I discovered that the front O2 sensor was plugged into the wrong connector by the previous owner. (Yes, there’s an identical connector near the airbox that is part of the body harness. I’m not sure what it’s for. Cruise control maybe?) The correct O2 connector was zip-tied up and out of the way.
-I have since plugged the O2 sensor into the correct connector. This eliminated the 176 error code.
Problem: I don’t know if the misconnected O2 sensor was the root cause of the mis-firings, because it wasn’t discovered until a month after the race.
My goal before the next race is to re-create the symptom by unplugging the front O2 sensor, and driving it hard, until it starts to miss. Then plug it back in, and immediately drive it hard again to see if the stumbling is eliminated. I have not been successful. I can’t achieve a miss with or without the O2 sensor plugged in. I feel like I’ve driven hard enough, but maybe not. I took it out on the freeway for a solid hour, O2 unplugged, flooring it in 3rd gear to redline, brakes to 50mph, then flooring it again, over and over, and nothing. No stumble. I checked the mpg with and without the O2 plugged in: 15.5 in both cases (hard driving)
During the race, as the car would stumble, we brought it in to the pits, replaced a component, and sent it back out. Each time, resetting the computer via battery **** switch. It would run normal for a few laps and then the symptom would return, progressing more quickly though. The rate of progression seemed to be inversely related to the length time spent in the pits. (more cool down time = more laps with no misses) We replaced components one at a time (DIS, TPS, MAF, plugs, wires, ECU, coil pack,) We did not replace the crank or cam sensor.
I’m fairly confident that the car will perform at the next race now that the O2 sensor is correctly plugged in, but I need to know for sure. My team mates want me to swap engines to avoid another DNF, unless I can prove the O2 was the root cause.
My question to all of you is: Is the stumbling symptom consistent with an O2 open circuit? Or, is there something else that I’m missing. On test drives, I’ve tried my best to reproduce the setup and conditions of the race. On my next test drive, I’m going to actually plug the O2 sensor into the wrong/unknown connector. (as it was at the race) Even though I have no idea what this connector is for.
Thanks for reading! Any input is much appreciated.
Occurrence: Hard driving on racetrack, WOT to redline, over and over. i.e. Racing. Ran perfectly for about an hour, then the first miss was felt. The subtle miss slowly progressed to a constant stumble under any load, and an inability to accelerate.
Facts: - Car – ‘89 w/ 100k. X2J computer. Stock except K&N and gutted cats. Cruise & AC removed.
-Error code: 176 – Oxygen sensor not switching – system is or was lean Left or Front HO2S – Fuel Control.
-This car is an ’89, so there was no MIL at the time. (I have since added one)
-After the race, I discovered that the front O2 sensor was plugged into the wrong connector by the previous owner. (Yes, there’s an identical connector near the airbox that is part of the body harness. I’m not sure what it’s for. Cruise control maybe?) The correct O2 connector was zip-tied up and out of the way.
-I have since plugged the O2 sensor into the correct connector. This eliminated the 176 error code.
Problem: I don’t know if the misconnected O2 sensor was the root cause of the mis-firings, because it wasn’t discovered until a month after the race.
My goal before the next race is to re-create the symptom by unplugging the front O2 sensor, and driving it hard, until it starts to miss. Then plug it back in, and immediately drive it hard again to see if the stumbling is eliminated. I have not been successful. I can’t achieve a miss with or without the O2 sensor plugged in. I feel like I’ve driven hard enough, but maybe not. I took it out on the freeway for a solid hour, O2 unplugged, flooring it in 3rd gear to redline, brakes to 50mph, then flooring it again, over and over, and nothing. No stumble. I checked the mpg with and without the O2 plugged in: 15.5 in both cases (hard driving)
During the race, as the car would stumble, we brought it in to the pits, replaced a component, and sent it back out. Each time, resetting the computer via battery **** switch. It would run normal for a few laps and then the symptom would return, progressing more quickly though. The rate of progression seemed to be inversely related to the length time spent in the pits. (more cool down time = more laps with no misses) We replaced components one at a time (DIS, TPS, MAF, plugs, wires, ECU, coil pack,) We did not replace the crank or cam sensor.
I’m fairly confident that the car will perform at the next race now that the O2 sensor is correctly plugged in, but I need to know for sure. My team mates want me to swap engines to avoid another DNF, unless I can prove the O2 was the root cause.
My question to all of you is: Is the stumbling symptom consistent with an O2 open circuit? Or, is there something else that I’m missing. On test drives, I’ve tried my best to reproduce the setup and conditions of the race. On my next test drive, I’m going to actually plug the O2 sensor into the wrong/unknown connector. (as it was at the race) Even though I have no idea what this connector is for.
Thanks for reading! Any input is much appreciated.
