bad o2 sensor?
03-27-2008, 03:43 PM
#1
bad o2 sensor?
well i hooked up my shortband o2 into one of the sensors and it always read that my car ran really lean. well i know it was always running rich becuase i got about 11mpg on a stock motor when i was babyin it, i got 18 easily when i bought it. and not to mention it smells like straight gas coming out of the exhaust. well i was thinking maybe my o2 sensors are bad, so my car thinks its running lean and throws in more gas and it just always shows lean. I was planning on hooking up the gauge to the other sensor but now my cars halfway torn apart and i could hook it up but i cant start the car with no engine in it to see if both sensors are messed up. does this sound like a something that would cause my car to run rich when the gauge says it runs leans? I dont wanna buy 2 new sensors for nothing. thanks guys.
on a better note my motor got shipped out this morning
on a better note my motor got shipped out this morning
03-27-2008, 04:07 PM
#2
2nd Gear Member
Join Date: Mar 2008
Location: Ft Worth, TX
Posts: 346
RE: bad o2 sensor?
It sounds logical but I have no prior experience with O2 issues on Mustangs. BUT.... on say a Eclipse for example 
what happens is the ECU tries to compensate for the lean/rich reading and will try to compensate for a period but if it fails to change the reading it will trigger a code and revert to open loop programming. I hate spending money on parts I am unsure about but if your MPG has decreased so much and without cause such has mods or anything I would say bite the bullet and replace the sensors. With prices jumping as they are it will pay for it self in the long run and if that's not the issue at least you know when they were replaced and trouble shoot further.
what happens is the ECU tries to compensate for the lean/rich reading and will try to compensate for a period but if it fails to change the reading it will trigger a code and revert to open loop programming. I hate spending money on parts I am unsure about but if your MPG has decreased so much and without cause such has mods or anything I would say bite the bullet and replace the sensors. With prices jumping as they are it will pay for it self in the long run and if that's not the issue at least you know when they were replaced and trouble shoot further.
03-27-2008, 04:41 PM
#4
2nd Gear Member
Join Date: Mar 2008
Location: Ft Worth, TX
Posts: 346
RE: bad o2 sensor?
Everything seems to be pointing to the O2 sensors or what ever is causing the ECU to up the gas. I have a 88 now that I am getting back up to speed, having gas smell in the exhaust also, but it sat in a field for 4 years so not sure on mine but thinking the engine temp sensor. On yours though and I may be wrong but you should be able to disconnect the O2 sensor(s) completely, it will cause a fault and CEL but should revert to factory programming, then at that point see if you still smellgas andhave low MPG's........ if so maybe EGR?
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