o2 sensor left unplugged question?

svt_cobra01 · Dec 9, 2015

my car is out the shop tomorrow morning, on the pypes o/r X my o2 sensors dont reach, the ones close to the engine. if they are left unplugged will i have engine problems like not sending the correct air fuel ratio or something of that nature? or is it just a issue that will make the computer throw a code? need info sorry for newbie question

Jon82387 · Dec 9, 2015

Yea.... those are the main oxygen sensors for each side.... if it was the rear ones i wouldn't worry a whole lot. But being as they are the fronts.......

If you are 100% set on driving it just to get it home and you live close.... you may be able to get away with it babying it.... i wouldn't get into it at all.

If you can hold off on getting the extensions that would be best.

It will probably run like crap.

svt_cobra01 · Dec 9, 2015

Jon82387 said:
Yea.... those are the main oxygen sensors for each side.... if it was the rear ones i wouldn't worry a whole lot. But being as they are the fronts.......

If you are 100% set on driving it just to get it home and you live close.... you may be able to get away with it babying it.... i wouldn't get into it at all.

do you know these things first hand? i called the mechanic and he said it will not effect the car at all, he said it is for the smog guys and your car will not run lean or rich. im not to sure about that, kinda seems like he just wants my money in hand and out of his shop. im placing the order first thing in the morning for the extensions but with americanmuscle its goina be 5bd standard shipping dont really want to pay for 1-3 days its kind of expensive. if i can get away with it for a week and just put the o2 extensions on as soon as i get them that would be best.

01yellercobra · Dec 9, 2015

He's correct. You need the front O2's in order for the car to run correctly. The rears are for smog. Did you go with headers or just the mid pipe?

svt_cobra01 · Dec 9, 2015

slo984now said:
He's correct. You need the front O2's in order for the car to run correctly. The rears are for smog. Did you go with headers or just the mid pipe?

i had them install a o/r X pipe im guessing it wasnt for my exact year because of the o2 sensor location. well im definetly driving the car out of there. by any chance do you know any stores i can walk in and just buy the extensions??or maybe a shop can somehow extend the wire? i will go straight there, pretty desperate at this point i really dont want to damage anything. all i can think of is autozone and they didnt have it.

01yellercobra · Dec 9, 2015

The mid pipes for the earlier years have the sensor location on bottom of the pipes. You can extend the wires. I did that before with solder and heat shrink.

If you unplug the MAF the computer goes into a limp mode. You might be able to do that to get the car home.

svt_cobra01 · Dec 10, 2015

slo984now said:
The mid pipes for the earlier years have the sensor location on bottom of the pipes. You can extend the wires. I did that before with solder and heat shrink.

If you unplug the MAF the computer goes into a limp mode. You might be able to do that to get the car home.

its on a 98 GT, i thought it would be ok to go at least a week without them plugged in as long as i dont be hard on it. got a new clutch installed so im driving like a grandpa until its broken in. ive heard of people doing the soldering and heat shrink method and some people said it was a bad idea because of the o2 not being able to heat up correctly with the extra wire. i really dont care about my plugs they are autolite and cheap anyways, if my gas mileage is affected a little so be it. my concern is engine damage because of the computer not reading any sensors in place. i have to go about 30 miles at the very least. when you say limp mode do you mean the car will bog down or something with the maf unplugged? this is turning out to be a huge headache. i should just put the stock mid pipe back on until i get what i need

decipha · Dec 10, 2015

if the ecu doesnt get a hego switch within its timeout (60 sec usually), itll fail that hego and use the other banks hego for both sides, with an x pipe you should disable the driver hego regardless

the car will only run odd for them 60 seconds or so where the ecu is dumping fuel on thay bank to get the hego to switch, as long as you dont keep shutting it off and restarting it then all will be ok for you to drive it

unplugging the maf is the absolute worse idea ever, thats even worse then changing the numbers on a winning lottery ticket, uess the maf has failed NEVER for any reason unplug the maf ever and drive your vehicle, there is absolutely nothing safe about it and it can only do more harm than good and while the ecu is shooting in the dark with no fuel feedback you need it to be as accurate as possible, unless you have a custom tune from a highly knowledgeable tuner that actually spent the time to manually dial in failure management mode the car will not be safe to drive like that even in an all stock setup its usually off alot more thab i consider to be acceptable

01yellercobra · Dec 10, 2015

Why would you disable the O2 sensor? You're probably thinking of people install long tubes and the transport delay and heater duty cycle need to be increased. You should never turn off the front O2's. The rear O2's can be turned off though.

Unplugging the MAF is not the worse thing you can do. That's why there's a table in the tune for it. I did it when I blew the intake pipe off. I didn't have my tools so I unplugged the MAF and drove home. The A/F was fine. I didn't go WOT like that, but the car drove fine.

svt_cobra01 · Dec 10, 2015

slo984now said:
Why would you disable the O2 sensor? You're probably thinking of people install long tubes and the transport delay and heater duty cycle need to be increased. You should never turn off the front O2's. The rear O2's can be turned off though.

Unplugging the MAF is not the worse thing you can do. That's why there's a table in the tune for it. I did it when I blew the intake pipe off. I didn't have my tools so I unplugged the MAF and drove home. The A/F was fine. I didn't go WOT like that, but the car drove fine.

my car needed a new throwout bearing so i installed a clutch kit from exedy and had them throw on my pypes o/r X pipe since They had to remove the stock H anyways on the new pipe the sensor location is further down and the o2 do not reach. i dont have a choice i cant plug them in once i pick my car up from the shop. i also dont want to turn of anymore sensors then the one that is already disconnected. i dont like taking chances espcially with my car.

svt_cobra01 · Dec 10, 2015

slo984now said:
Why would you disable the O2 sensor? You're probably thinking of people install long tubes and the transport delay and heater duty cycle need to be increased. You should never turn off the front O2's. The rear O2's can be turned off though.

Unplugging the MAF is not the worse thing you can do. That's why there's a table in the tune for it. I did it when I blew the intake pipe off. I didn't have my tools so I unplugged the MAF and drove home. The A/F was fine. I didn't go WOT like that, but the car drove fine.

im not willingly disconnecting the sensor, it will no longer reach with the new x pipe and the shop does not do any extensions or wiring of any kind so im screwed.

01yellercobra · Dec 10, 2015

svt_cobra01 said:
im not willingly disconnecting the sensor, it will no longer reach with the new x pipe and the shop does not do any extensions or wiring of any kind so im screwed.

My post wasn't in reference to you. It was in reference to decipha. Sorry about the confusion.

At this point you might want to consider having the shop put your stock mid pipe back in so you can figure out the O2 issue.

svt_cobra01 · Dec 15, 2015

slo984now said:
My post wasn't in reference to you. It was in reference to decipha. Sorry about the confusion.

At this point you might want to consider having the shop put your stock mid pipe back in so you can figure out the O2 issue.

oh ok. well ive been driving the car but only for about 20 minutes at a time, it runs perfectly fine for a while but once i stop and turn it back on or about 15-20 minutes past the computer seems to kick back in and register no o2's connected. it has stalled me while sitting at a light a few times, and the worst part it if it doesnt stall me it will rev my car to 2k and 2 1/2 rpm holding it there and that is NOT a good thing the car is loud and will definetly catch the attention of a LEO. the o2 extensions should be comming anyday so should be ok. disconnecting the battery overnight seems to make the car drivable for short trips.

Harding27 · Aug 12, 2017

I know this thread is old but I will throw this question out there anyway. Recently had a Mac Pro chamber and Borla stingers installed. The front 2 o2 sensors are plugged it and in fine working order. The same can't be said for the rear o2 sensors. The driver side rear o2 sensor just barely reached but is plugged in and the rear passenger side won't reach at all so I had to order o2 extensions. I noticed on the drive home with one rear sensor unplugged the car didn't run like it's usual self. Loss of power through all gears with obviously a bad smell of fuel/fumes. The CEL came on as well and my tail pipes were yellowish when I got home which probably means it's running rich? Would a rear unplugged o2 sensor cause there issues?

RX1Cobra · Aug 16, 2017

The rear O2 only tells the computer if you're cats are working. The car should run fun without them but will trip a CEL. Did you install an O/R pro chamber? If so that's why you're smelling gas... you don't have cats anymore.

I'd guess the yellow is probably a coating that was inside the exhaust burning off. If you're running rich the coating/exhaust will be black.

o2 sensor left unplugged question?

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