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Rich air fuel ratio!!!!!

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Old Apr 29, 2010 | 08:30 PM
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Default Rich air fuel ratio!!!!!

i hooked up my LM1 meter to my friends gto and i was getting crazy air fuel ratio readings. when the car idle's the air fuel is at like 9.8-10.4 which i know is way to rich. then when he drives the car steady @ like 2500-3500 steady the car is still @ 10.0 air fuel ratio.

when he really gets on the car the air fuel goes to normal like 13.5-14.5

but when he lets off the gas and costs the car goes all over from 16.00-50.00

could the O2 sensor be the only cause?? has anyone ever hooked up the meter to there cars ??
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Old Apr 29, 2010 | 10:42 PM
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With readings like that at idle the car shouldnt even run, and if it does there would be a huge cloud of blue smoke coming out the exhaust. Has he had someone put a tune on this thing?
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Old Apr 30, 2010 | 07:41 AM
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It always could be the sensor.

If the sensor is right the car is all jacked up. Needs a tune terribly!!! Its too rich at idle, too rich at cruise, too lean at WOT, but the decel part seems right though.
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Old Apr 30, 2010 | 07:55 AM
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Stupid question, but where is the sensor? In the Y or in the tailpipe? Is this a WB02, or a typical o2?
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Old Apr 30, 2010 | 08:14 AM
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the only thing that was changed on the car was headers wit catless mids. also the spark plugs were changed to the NGK TR6 (TR55) plugs gaped to 45, cause thats what i have in my ls6 corvette so i figured the gap would be the same.

i didnt think that the car would need a tune wit such little work done to it.

the O2 sensor on an 04 gto is 2 in the header collectors and 2 in the mid pipes. the ones in the midpipes are to test for the catalytic converter working properly so i took that out and put in the LM1 meter O2 and took my reading from there.

where could my friend get a tune and how much would it be to fix this problem, and im assuming that he cant do it with a diablo tuner

thanks

Anthony
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Old Apr 30, 2010 | 08:20 AM
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Based on what I was told by a tuner a while ago regarding the heads; The LT's flow more and the o2's pick up on the extra air flowing past the sensor and they richen the mixture accordingly.

Dyno tunes are around $400. All depends on where you are as far as WHO to go to.
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