Afr on decel

[Rob09msport]

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

 

[Twisted Tuning]

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.

 

[Rob09msport]

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.

 

[Blackarrow335i]

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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!

 

[White Sands]

Same here, have this issue after replacing injectors to index 12's. Bank 1 is lazy to get back to 234 on deceleration. Reset adaptations using INPA an still didn't help, no burble tune either and pre-cat o2's have been replaced less then 5000 kms ago. Thinking it could be leaking injector(s) in bank 1?

 

[JohnDaviz]

Had the same issue with bank 1. We figured my O2 sensor was diagnosing a shot turbo that was leaking into the downpip.

 

[Rob09msport]

Mine was internal crack in valve cover. If you dont have external low side pcv and blocked head ports a crack can leak oil into the combustion chamber.

 

[White Sands]

Not sure if my VC is cracked but I will be replacing it as preventative maintenance soon, hopefully it solves the issue. If not I can return the bank 1 injectors to FCP and try a new set.

 

[Rob09msport]

Easy test is stay out of boost and see if afr acts normal when you let go of throttle it should stop being lazy if you stay in vac for min or 2 cause no pressure pushing anything through crack so it cleans itself out kinda. Still will mes afr a little sometimes but at least you will isolate it from injectors

 

[White Sands]

Ok I’ll try logging that way then. If it is apparent that the AFR acts normal under these conditions what would be the issue?

 

[Rob09msport]

Ok I’ll try logging that way then. If it is apparent that the AFR acts normal under these conditions what would be the issue?

Could be bad pcv or turbo seals if isn't injector

 

[White Sands]

 

[335iN54]

Not sure if my VC is cracked but I will be replacing it as preventative maintenance soon, hopefully it solves the issue. If not I can return the bank 1 injectors to FCP and try a new set.

Just wondering Did you manage to fix this issue?