Nistune Forums

Hi, Matt.
I have a problems:
1. At idle (TPS idle sw on) AFR Alpha always 113%, AFR is ~12,5. Once the throttle open, AFR Alpha go to 100%. If the throttle closed, AFR Alpha again go to 113%.
The problem is when O2 sensor feedback is on (raw value more than 128) and throttle is closed, speed signal no more than 0.
2. Also AFR Alpha at idle go to 113% when Estimated A/F ratio = 14,7 (O2 feedback is off or is on, does not matter). When Estimated A/F ratio is richer than 14,7 AFR Alpha is 100%.
How to control the AFR alpha?

My car: Nissan Skyline ECR33, RB25DET S2, Z32 MAF, Nismo 555 Injectors, Q45 S2 throttle body (0.50V at IDLE), Z32 ECU (23710-46P65), Nistune type 2 board (base image is 23710-41P03 REV 14U, daughterboard is 23710-41P14).
Thanks.

P.s.: forgive I from Russia, I hope you me you understand

Really nobody knows?

AF Alpha / AF Alpha learn (aka short term and long term trims) are controlled by the O2 sensor feedback. They are the amount of adjustment required for the ECU to maintain 14.7:1

When the O2 sensor detects that fuel is to be added then these values increase, when it needs to lean out then the values decrease. These adjust the resulting injection time as a multiplier to maintain stoich

Reset these trims using Operations > Active Tests > Clear Self Learn > Set > Start then Stop

I have the ability to vary the O2 sensor feedback on the bench. When the tune contains a richer/leaner tune (using K and fuel map values) then it will adjust the injection time, affect AFRs and then using the O2 sensor will adjust these trims accordingly.

By altering the fuel map / K constant will subsequently affect these trim levels