How flexible is the ECU?

6SPD_FTW · 06-18-2009, 04:53 PM

I'm not certain, but 20 miles is a bit short for the ECU to re-learn fuel trims. It usually takes a full 200-300 miles for full re-learning. And WOT acceleration doesn't do ANYTHING at all for helping the ECU re-learn fuel trims. The ECU goes into open-loop at WOT and completely ignores the AFR sensors and doesn't tune the AFR at all. Only at idle or part-throttle does the ECU pay attention to the AFR sensors.

As far as the ECU reset procedure above, it may be good to learn it...

The idle-air relearn procedure is accomplished the SAME way as above. The only difference is on the last step, when you floor the gas pedal and the SES light starts flashing after 10 seconds, if you RELEASE the accelerator pedal, the SES will flash out error codes (0000 is no faults), if you stomp the accelerator pedal, it will clear the ECU fuel trims. HOWEVER, if you do NOT release the acc. pedal and continue to hold it down for a full 20 seconds, the SES will stop flashing and turn ON. If you start the engine within 3 seconds, the ECU will perform the idle air relearn. That will be important for any mods to the air induction system.

Conditions that must be met: engine at operating temp, steering wheel straight ahead, all accessories off, doors closed, transmission in N and parking brake set.

Late,
Trav

06-18-2009, 04:53 PM	#22 (permalink)
6SPD_FTW Base Member Join Date: May 2009 Location: Bristol, VA Posts: 59 Drives: 09 370Z Bl 6MT Rep Power: 17	I'm not certain, but 20 miles is a bit short for the ECU to re-learn fuel trims. It usually takes a full 200-300 miles for full re-learning. And WOT acceleration doesn't do ANYTHING at all for helping the ECU re-learn fuel trims. The ECU goes into open-loop at WOT and completely ignores the AFR sensors and doesn't tune the AFR at all. Only at idle or part-throttle does the ECU pay attention to the AFR sensors. As far as the ECU reset procedure above, it may be good to learn it... The idle-air relearn procedure is accomplished the SAME way as above. The only difference is on the last step, when you floor the gas pedal and the SES light starts flashing after 10 seconds, if you RELEASE the accelerator pedal, the SES will flash out error codes (0000 is no faults), if you stomp the accelerator pedal, it will clear the ECU fuel trims. HOWEVER, if you do NOT release the acc. pedal and continue to hold it down for a full 20 seconds, the SES will stop flashing and turn ON. If you start the engine within 3 seconds, the ECU will perform the idle air relearn. That will be important for any mods to the air induction system. Conditions that must be met: engine at operating temp, steering wheel straight ahead, all accessories off, doors closed, transmission in N and parking brake set. Late, Trav