AFR fluctuation

SOHCitTOem · Post by **SOHCitTOem** » Mon Nov 03, 2008 9:37 am

My motor does this wierd thing where it goes extremely lean when releasing the gas then extremely rich while pressing the gas. I don't know how to alleviate this. Can someone have a look at my datalog file and tell me what I'm doing wrong? I've been having this problem for quite some time. And if you any comments on my .cal let me know because it's my first time tuning. ThANKS. setup- d16y5 block, p29 pistons, d15b head, crower stg. 3 cam.

Garrett · Post by **Garrett** » Mon Nov 03, 2008 12:34 pm

when you lift the throttle the ecu fuel cut or your datalog when you are at 30% (the max seen in your log) your AFR is about 13.5-13.9 it's a little bit lean

borat · Post by **borat** » Mon Nov 03, 2008 1:44 pm

eCtune has some settings to compensate for this, but in general, what you're seeing is normal. The ECU can't tell exactly how much air is coming in to the engine under transitional loads, so it compensates the best it can, but it's never going to be perfect.

SOHCitTOem · Post by **SOHCitTOem** » Tue Nov 04, 2008 1:27 am

I see what you guys are saying though, that it's never going to be 14.7 throughout the transition off and on throttle. Would I have to tune my tip-in/tip-out to alleviate this? What AFR's should I be shooting for in my setup? I'm not giving it full throttle yet bcuz I am still breaking in the motor and I don't have access to a dyno.