well what is going on is i get random intake backfire during rev matching down shifts or feathering the throttle in a slide i never had this problem before my af's are good when i loged 3rd and 4th gear pulls i have no knock either from my understanding is that intake backfire is due to lean conditions correct but what is strange is the wide band never see a lean condition when it does happen.
idle afrs float around 14.1 to 14.7
under load at full boost 11.5 to 12.1

im on e85 fyi with dual walbro 255hp pumps

ive replaced fuel filters + pump socks

ive checked fuel pressure and it is good

ive checked for vacuum leaks ect....

noted that im a full time mechanic that is well under paid lol

so any assitance will be a great help but i will understand if your tuning knowlege can not be shared i completely understand but please pm me with any info i will keep all tips between me and whom ever

thank you very much for taking the time to read my bs but please help
Duberx (David)

 

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