Afr on decel

Twisted Tuning

Lieutenant
Platinum Vendor
Oct 25, 2016
762
New York
#22
Well turns out is my cracked valve cover . If I keep out of boost I have perfect afr rock solid 234.9 if I hit boost and let go bank 1 is mess and 2 is sloppy
Both of those are in boost. I still dont see how a crack in the VC causes a rich overrun. unless you have a lot of burnable vapors in the PCV system. which you shouldnt. oil burns but doesnt ignite. Unless like I said before you have fuel oil dilution bad.

Maybe my brain is tired. And I'm missing something. VC cracks should cause leaner conditions if it's coming through the head ports.
 
Oct 28, 2017
832
Monroe CT
#23
I posted wrong logs I clicked the sort button and had oldest not newest at top sorry these show it much better. It is brand new oil is the really weird part as far as dilution. Basically if I run boost for a little then it will do it but if I stay neg for little it's perfect and I can stab throttle for sec and so on. Idk if maybe oil vapor could just throw off o2 readings slightly I have always been under impression that oil will drop octane and can burn though. I also found a long hill and logged 3 min without a hiccup. Idk if biosyn oil is alot dif than reg oil either.
 

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#24
D
I posted wrong logs I clicked the sort button and had oldest not newest at top sorry these show it much better. It is brand new oil is the really weird part as far as dilution. Basically if I run boost for a little then it will do it but if I stay neg for little it's perfect and I can stab throttle for sec and so on. Idk if maybe oil vapor could just throw off o2 readings slightly I have always been under impression that oil will drop octane and can burn though. I also found a long hill and logged 3 min without a hiccup. Idk if biosyn oil is alot dif than reg oil either.
Did you ever fix this issue? Bc i have the exact same problem! And Cant Figur it out and it get really bad gas mileage too!
 
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