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  #1  
Old 08-22-2010, 04:33 PM
StarquestRescue StarquestRescue is offline
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Default Afr drop for no apparent reason?

Car is a Conquest with 850/1400 injectors and base maft. Timing is distributor controlled. It does have a knock sensor that can pull 7 degrees.
I keep running into a afr drop for no apparent reason. Seems to happen around 1350-1400 hz but if anything the duty cycle shows a small dip at the same time. I did notice duty cycle is about 80-82 % when it happens. Rpm can vary. Any input on why it is happening and how to tune it out?

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Old 08-22-2010, 08:20 PM
TurboBob TurboBob is offline
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a misfire shows as a lean spike. Have you tried reducing the plug gap a little?

B
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Old 08-22-2010, 08:32 PM
StarquestRescue StarquestRescue is offline
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Quote:
Originally Posted by TurboBob
a misfire shows as a lean spike. Have you tried reducing the plug gap a little?

B
But it is going rich not lean. I have other logs where the afr was 12 to 12.5 right before the dip.
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Old 08-22-2010, 08:37 PM
TurboBob TurboBob is offline
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oh, you mean the long richer section, not the lean spike at the end.

The dutycycle would have to increase to make things richer.

Hows the fuel pressure?

do you have other logs showing this?

Bob
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Old 08-22-2010, 09:47 PM
StarquestRescue StarquestRescue is offline
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Here i tried to tune it out. Up hill was better, down went lean. Afc air flow was mostly below the 1400 hz except for right below the dip on the up hill. I usually do not make down hill pulls because of inconsistency in the past.


Last edited by StarquestRescue : 08-22-2010 at 09:50 PM.
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  #6  
Old 08-23-2010, 12:14 AM
TurboBob TurboBob is offline
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might make sense to log battery voltage and fuel pressure.

Bob
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