I have a zeitronix wideband the 02 sensor is welded into the down pipe.

When I go wot my afrs are around 10 to 11 but as soon as i let off throttle my afr jumps to 21 and stays there untill i touch the throttle again. Basically it happens when i decellerate.

I attached a log of my car

What would be causeing this?

-Boost Leak
-fuel Pump Is bad

I also have my avcr+zeitronix+ smc alky boost line all tapped off of the fuel pressure regulator


MODS:
780cc precision fuel injectors
Shearer Fab turbo kit
Walbro 255 fuel pump
Hks 280 cams

 

sounds normal bro.

 

The reason this happens is because the engine becomes sort of an air pump when still in gear and there is no load on the engine....this will happen all the time....no need to freak out...

 

haha ok thanks guys i was just tripping out there was no knock so i wasnt to worried.

thanks for the quick replys

 

ECU cuts off spark and fuel during deceleration giving you happier fuel mileage thus pumping air through.