I've posted some other threads on this... I'm in the process of trying to diagnose some odd tune issues with my Harrop supercharged car and Ecutek tune. While doing one of my many datalog sessions I noticed some odd behavior that I'm curious if it's normal or not...
With the car fully warmed up and at idle my short term trims are ~-10% (Yes, I know this means I need to have my MAF scale tweaked). That's not the odd part, what's odd is when I step on the brake pedal I notice the AFR lean out then the fuel trims jump back up to basically zero for a few seconds as the closed-loop brings the AFRs back to 14.7.
Is this normal? I know the brakes are vacuum assisted and pumping the pedal does change the vacuum load on the engine, but should it be THAT drastic?
If it's abnormal, what on earth could be causing it? If it's to be expected then I'll disregard and move on to the next unlikely thing that could be causing my problems
-Matt