I was under my car the other day and noticed the o2 wire on the drivers side was unpluged. Now the car has been running fine with it unplugged. I plugged it back in and went for a ride. It was fine for a few mins htne it starting bucking, pooping back through the intake, etc. only at part throttle though. if I got into it it was fine. I assumed the o2 was bad and the previous owner just unpluged it? well I bought a new one "drivers side" put it in and the same thing happened.

few questions here

should it run fine with the o2 unplugged ?
is it possible that both were bad ?
if i replace the other one and it still does this what else could it be ?

Drew

 

ttt

 

any ideas ?

 

he could have had it programed to run with out them?????

 

I talked to someone on the phone the other day and was told something wierd. When I had my car hooked to a scanner it showed that the check engine light was out. My friend had siad that if the check engine light is the car goes into open loop. That it is only a complete circut when the buld is working. He said that may be what is causing my car to run like crap with the o2 plugged in. Any truth to this or any ideas ?

 

He says that the SES bulb completes the "permissions" for closed loop operation? No. It doesn't go into closed loop either because 1) there is a faulty O2 sensor, or faulty O2 heater circuit 2) there is a faulty coolant temp sensor or too low a coolant temp.

You say your scan shows the "check engine light was out"... I assume you mean there was a fault code for the SES light not working.

What happened is becoming fairly apparent at this point, if that's what you mean. The engine was running like crap in closed loop, so he unplugged the O2 sensor. That forced it to stay in open loop, and eliminated what was probably the bad effects of a faulty sensor, or other problem causing the engine to run rich or lean in closed loop. Unplugging the sensor sets a code and turns on the SES light, so he then either removed the bulb or cut the wire so you wouldn't know the SES light was on.

You need to get everything restored, including the SES light and/or wiring, then work on solving the poor running condition in closed loop. Gonna take some scanner work.

 

yes it set a code fo ses light. I do have a small crack in the overflow tank and the low coolant stays on constantly "it is never low on coolant though" so if both o2's are new and when plugged in it runs like crap what else should I check??

 

Low coolant light is a VERY common problem. Sensor gets dirty. Clean it or replace it. Has no affect of any knid on the way the engine runs... it is only connected to the light on the dash. Crack in the overflow tank shouldn't affect anything either.

You need to use the scanner to check all the sensors and calculated parameters with the O2 sensors hooked up. Most likely you are going to find the long term fuel corrections (BLM's) are really screwed up.

When you reconnect the O2 sensors with new sensors, how long did you let it run to see if it started to run better? Have you tried cleaing the PCM before you start it with the new sensors plugged in? That will get any whacked BLM's cleared out, and let it start rebuilding the long term corrections with good sensors. If that doesn't work, start looking for other problems... .exhaust leaks before the O2 sensors, excessive misfires, etc.

 

I went last night and diconnected both o2's. I then cleared the codes from the computer and hooked them back up. I started the car let it idle for a few min's. I then went or a ride. it was ok for about 3 min then started acting up at part throttle. popping through the intake bogging, etc. at wide open throttle it all goes away though. I unhook th o2's again and it runs fine. The only codes it is throwing is the ses light, and now a quad driver?? I checked the harness it seems to be ok but im not 100 percent sure. I only checked for visible signs of cracks or wear.

Drew