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apba12m
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Joined: November 08, 2011
Posts: 60
Location: michigan
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 Posted: Mon Jun 18, 2012 12:10 pm Post subject: cylinders 1 and 2 lean at Idle |
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| all stock 74 just rebuilt and with the a/f meter the 1-2 cylinders run leaner at idle than 3-4 1.0 lamda compared to 1.4 on 1-2 bank. any one else notice this? at speed A/F ratio is fine. |
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nikita
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Joined: September 16, 2007
Posts: 522
Location: California
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| Posted: Fri Jun 22, 2012 8:34 am Post subject: |
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| Distribution with this long tubular manifold setup, especially at low velocity idle, is going to be uneven. The fact that its ok at speed is a gift. |
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apba12m
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Joined: November 08, 2011
Posts: 60
Location: michigan
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| Posted: Mon Jun 25, 2012 4:56 pm Post subject: |
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| I think you are exactly right it is the intake manifold being long and unequal. only other possability is an exhaust leak upstream of my o2 sensor. I have checked the intake for leaks with propane and found none. |
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SilverThing 
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Joined: July 19, 2004
Posts: 633
Location: Boise/Seattle
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| Posted: Tue Jun 26, 2012 8:25 pm Post subject: |
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First thing that crossed my mind was a manifold boot leak, but that would show at speed as well.
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Wildthings
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Joined: March 13, 2005
Posts: 19889
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| Posted: Tue Jun 26, 2012 11:23 pm Post subject: |
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| SilverThing wrote: | | First thing that crossed my mind was a manifold boot leak, but that would show at speed as well. |
A manifold leak is going to have far more effect at idle than under load. A leak that would cause a continuous miss at idle might well not effect the combustion at speed and under load at all. |
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