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Car running better with O2 sensors unplugged?

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Old 08-05-2012, 02:53 PM
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Default Car running better with O2 sensors unplugged?

I made a thread about some problems I was having before with my car. It was just not running right, the main thing I noticed was when I'd slow down or come to a stop the cars would idle very low and sound like it was going to stall. I tried a lot of different things to help the car but had no luck. I unplugged the O2 sensors just to try something else and I haven't had the problems since.
I was wondering if I should go ahead and just replace the O2 sensors or if this could mean something else.
Thanks in advance for any help.
Old 08-05-2012, 04:43 PM
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If your car runs better with the o2 sensors unplugged your sensors are on the way out. Wouldn't hurt to replace them.
Old 08-05-2012, 05:25 PM
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also try cleaning your MAF and IAC .
Old 08-05-2012, 05:54 PM
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you can unplug the rear ones and it will run fine but ses light will come on you can have it tuned out
Old 08-05-2012, 07:00 PM
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You should not unplug your front O2 sensors because they control your air fuel mix.
Old 08-06-2012, 11:23 AM
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You should not unplug your front O2 sensors because they control your air fuel mix.
The car has other ways of compensating for that, so it's not like his engine would explode if he unplugs the front sensors.
Old 08-06-2012, 11:44 AM
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Originally Posted by redtan
The car has other ways of compensating for that, so it's not like his engine would explode if he unplugs the front sensors.
OK then unplug your O2 sensors and don't worry about it....LMAO.
Old 08-06-2012, 08:13 PM
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Did you see if the problem went away if the O2 sensors were plugged in but the MAF was unplugged?
Old 08-06-2012, 08:30 PM
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Originally Posted by DisasterFormula
Did you see if the problem went away if the O2 sensors were plugged in but the MAF was unplugged?
I haven't tried that yet, I'll be sure to tomorrow.

What will it mean?
Old 08-06-2012, 11:54 PM
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Originally Posted by LS1121
You should not unplug your front O2 sensors because they control your air fuel mix.
Your car will run in open loop with no 02s which is fine. Just runs rich as hell.
Old 08-07-2012, 06:15 AM
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A dirty or bad MAF sensor will also give you a rough running engine.
Old 08-07-2012, 08:30 AM
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Get a decent scan tool and check to see what the 02s are doing if they are switching properly and arent getting lazy. I have actually had a engine fail after running it hard for a long period of time with the 02 unplugged it leaned out and melted a piston, it was not a gm so I am sure it is a different system but I would be careful.
Old 08-07-2012, 10:20 AM
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Originally Posted by TZ2884
I haven't tried that yet, I'll be sure to tomorrow.

What will it mean?
When everything is plugged up and the car is warmed up, it'll run Closed loop. If you unplug the maf, it still runs closed (accepts input from the O2 sensors), but in speed density mode. If you unplug the O2s, it puts the bank w/ the unplugged sensor into open loop mode. So if you unplug the MAF and plug in the O2s and it runs good, that means you probably have a dirty or bad MAF. Especially if you run a K&N Filter. The oil on those things loves to fck with your MAF. Another possibility is a bad IAT Sensor.
Old 08-07-2012, 03:08 PM
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Originally Posted by garygnu
also try cleaning your MAF and IAC .
this and replace ur o2's,and u good
Old 08-07-2012, 03:37 PM
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Is your car throwing a SES? You can get rear simulators, or have them tuned out.
Old 08-09-2012, 09:55 AM
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There are no rear o2's, they have been tuned out. I still haven't had a chance to plug the fronts back in and unplug the MAF. Hopefully I'll have time to do it tonight. Is there some type of test I can do on the oxygen sensors to see if they're bad without a scan tool?
Old 08-13-2012, 06:14 PM
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Strange thing I noticed today, I plugged the o2s back in, I sat in the car and revved it up to 2500 rpm to hold it steady there. It dropped to ~2470 and then after a couple seconds went back up to ~2500 then went back down and back up every few seconds. I've ordered a scantool that should be here in a couple days, but does anyone have any ideas?
Old 08-13-2012, 07:55 PM
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Flooding the engine with fuel can't be good.
Old 08-13-2012, 07:59 PM
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Originally Posted by LS1121
Flooding the engine with fuel can't be good.
I don't understand, are you saying that it's flooding? Or are you talking about when I had the sensors unplugged?
Old 08-14-2012, 12:00 AM
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when you had the sensors unplugged.


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