symptoms of a bad o2 sensor.......

Vegas Smith · Jan 22, 2003

symptoms of a bad 02 sensor.....my car has severe hesitation....gets sub-par gas mileage and smells rich.......but here is the tricky one. i have an a/f gauge.....it used to work but a few months ago it just stopped working, tried diferent fuses ect....just doesnt work anymore, but still lights up so i know its not the gauge. ironically this was about the same time my car started going downhill, could it be that the o2 sensor just plain blew out, and when i hit boost the car becomes too lean or too rich, causing hesitation?

brian9397gsx · Jan 31, 2019

Look for soot around joints. But with an exhaust leak I'd guess you would be going lean not rich. Your symptoms seem like a boost leak. The only sensor that is going to come into play to cause your overly rich concern is the mas. At wot the oxygen sensor gets disregarded and the ecu does fueling based on its tables. If your mas is reading more air than the engine is taking in your going to go rich. How are you doing your blt? And what psi are you testing to? Some leaks are hard to find especially if you've got an air compressor hammering away in the background.

Tony818 · Jan 31, 2019

brian9397gsx said:
Look for soot around joints. But with an exhaust leak I'd guess you would be going lean not rich. Your symptoms seem like a boost leak. The only sensor that is going to come into play to cause your overly rich concern is the mas. At wot the oxygen sensor gets disregarded and the ecu does fueling based on its tables. If your mas is reading more air than the engine is taking in your going to go rich. How are you doing your blt? And what psi are you testing to? Some leaks are hard to find especially if you've got an air compressor hammering away in the background.

I'm doing my BLT at the throttle body and at the turbo inlet at around 20 psi. I turn off the compressor once it's full and listen to sounds while spraying soapy water around injectors throttle body intercooler piping. I might have to test both mas and see if maybe I just have 2 bad ones. Is there anything else that would cause it to run rich only in boost?

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symptoms of a bad o2 sensor.......

Vegas Smith

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Tony818

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