The readings should be fluctuating rapidly esp at 2500 rpm.
Having more than 10% differential at idle & 2500RPM can be due to several things: including a charcoal canister that has a lot of fuel vapors from the tank. Also the Governor (EHA) could have a slight misadjustment of the BASE differential pressure. Vacuum leaks can also cause this problem. Try adjusting the Lamda at idle to say 20% & then see what happens the higher reading. AS long as the duty cycle changes at idle & at 2500 you WON'T have any problem!!!
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