Engine weird a/f ratio, need help.

RadioFlyer · 06-03-2016, 10:58 AM

Is the ecu stock or tuned? Also, what intakes are you on? If you're idling for 5 mins, your intake is probably picking up heatsoak from the engine, so you're getting into the different temp compensation fuel trim tables. So if any of your 'learned' fuel trims get applied to the rest of the tune, you end up with 'target of 14.7' but applying the learned fuel trim of something like -10% fuel, so it results in leaning out your closed loop afr to 15.X.

Disclaimer: I'm not super familiar with the architecture of the Nissan ECU, so I'm not sure if this applies. When I tuned my car with the UpRev Tuner cable, I didn't have access to the temp compensation tables. But in general, you want your closed loop corrections minimized or else you could potentially be applying corrections to your whole tune, which is what it sounds like is happening here.

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06-03-2016, 10:58 AM	#2 (permalink)
RadioFlyer Base Member Join Date: Aug 2014 Location: Los Angeles, CA. Posts: 193 Drives: 08 G37S S/C Rep Power: 40	Is the ecu stock or tuned? Also, what intakes are you on? If you're idling for 5 mins, your intake is probably picking up heatsoak from the engine, so you're getting into the different temp compensation fuel trim tables. So if any of your 'learned' fuel trims get applied to the rest of the tune, you end up with 'target of 14.7' but applying the learned fuel trim of something like -10% fuel, so it results in leaning out your closed loop afr to 15.X. Disclaimer: I'm not super familiar with the architecture of the Nissan ECU, so I'm not sure if this applies. When I tuned my car with the UpRev Tuner cable, I didn't have access to the temp compensation tables. But in general, you want your closed loop corrections minimized or else you could potentially be applying corrections to your whole tune, which is what it sounds like is happening here.