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 Post subject: fast af problem
 Post Posted: Mon Aug 09, 2010 10:57 am 
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i have a fast af meter, the dual type with sensors in both left and right collector.. when the ignition is on but the motor not running the reading on the meter jumps around dramatically, swings from 13 up to 21 afr.. this is with the motor not running.. does this mean the sensors are faulty or the meter itself.


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 Post subject: Re: fast af problem
 Post Posted: Mon Aug 09, 2010 11:21 am 
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zephyrc wrote:
i have a fast af meter, the dual type with sensors in both left and right collector.. when the ignition is on but the motor not running the reading on the meter jumps around dramatically, swings from 13 up to 21 afr.. this is with the motor not running.. does this mean the sensors are faulty or the meter itself.


So what does it do with the engine running? :-k

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 Post subject: Re: fast af problem
 Post Posted: Mon Aug 09, 2010 11:44 am 
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It depends on your exhaust system, but it can take days for the residual gasses to leave the system. They are actually reading O2 content of the air they are sampling. If you're concerned, take them out of the system and check them in a free air condition, they should read steady and FAST can tell you what they should read in free air.

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 Post subject: Re: fast af problem
 Post Posted: Wed Aug 11, 2010 2:09 pm 
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ken, with the engine running the af meter swings rapidly up and down between about 13 ---21.. does the same with the motor not running..
slowpoke, will remove them from pipes and check in free air


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 Post subject: Re: fast af problem
 Post Posted: Wed Aug 11, 2010 2:36 pm 
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zephyrc wrote:
ken, with the engine running the af meter swings rapidly up and down between about 13 ---21.. does the same with the motor not running.


So is the engine running in a manor that the AFRs indicate, ie, is it running OK at idle and part throttle down the road or is it missing and such?

And yeah, remove the sensors and do a free air calibration.

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 Post subject: Re: fast af problem
 Post Posted: Wed Aug 11, 2010 4:36 pm 
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put an extension on the collector...A piece of pvc will work, needs to be 3' long

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 Post subject: Re: fast af problem
 Post Posted: Wed Aug 11, 2010 5:28 pm 
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Beretta wrote:
put an extension on the collector...A piece of pvc will work, needs to be 3' long


Barry, this is a STREET car over in the UK so it's got a full exhaust system on it now. ;-)

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 Post subject: Re: fast af problem
 Post Posted: Wed Aug 11, 2010 7:51 pm 
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:-# :-# ](*,)

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 Post subject: Re: fast af problem
 Post Posted: Wed Aug 11, 2010 8:52 pm 
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Beretta wrote:
:-# :-# ](*,)


Here is a link to a pic of his car. Scroll down the page and you'll see it.

viewtopic.php?f=3&t=5692&p=52462#p52462

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 Post subject: Re: fast af problem
 Post Posted: Sat Aug 14, 2010 4:25 pm 
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ken, it seems to be running ok , its just that the o2 sensor are all over the place.. am in the garage tomorrow and will do the free air test on them... thanks for the help


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 Post subject: Re: fast af problem
 Post Posted: Mon Aug 16, 2010 2:20 pm 
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took the sensors out for free air test and one read 21 and the other read 9.. cleaned them with carb cleaner and put them back in.. they both read about 16 at idle but only ran it for a couple of minutes.. will run it for half hour tomorrow


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