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Lean AFR during low boost...

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alexv
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2014/05/30 13:50:11 (permalink)
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Lean AFR during low boost...

91 turbo with ct20b.
Something I just noticed while driving uphill in high gear (4th or 5th mostly) is that it starts to make low boost (above 0 to 0.5 bar) but the air/ fuel ratio is still in the low 14s or high 13s at best! If I downshift, it will start making more boost and the AFR will get to a reasonable ~12 or under but I was wondering if anyone else was experiencing that? That doesn't seem safe at all...
On flat road or at WOT the AFR is good at 10 to 12, so the problem is only at cruising speeds going uphill in high gears.
 
Cause for concerns or not so much?
#1


3 Replies Related Threads
    Deco
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    Re: Lean AFR during low boost... 2014/05/30 14:15:48 (permalink)
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    I wouldnt be too worried. Mine floats around 16 until I hit boost where it then sinks to 14 (around 3k rpm) and goes down to high 10s by redline. My tuner said although they arent ideal numbers, there is no evidence of it causing damage and as long as its not lean on high boost nothing is going to pop. Though I wouldnt be trying to boost in 4th/5th unless the rpms were high enough otherwise your adding boost to a lean mixture. 

    1994 GT with 96 3SGTE (217rwkw)


    #2
    Mrskylighter
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    Re: Lean AFR during low boost... 2014/05/30 14:19:08 (permalink)
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    I think this is a common trait of the gen 3 efi system. 
    #3

    alexv
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    Re: Lean AFR during low boost... 2014/06/01 12:48:47 (permalink)
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    Thanks, that's a relief :)
    #4
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