Hondata

I have been experiencing this issue since day one with the Hondata. I can get the fuel spot on at idle (14.7) with the car at full operating temperature, and zero corrections, neither timing or fuel comps. I drive the car for a bit, then come to a stop and once the engine is back at idle, the wideband will read 13.0-14.0. Then I can drive some more and once back at idle it will read 14.7. Or, it will be at 14.7 while idling, then if I turn the car off and restart it will read either lean (16ish or rich 13ish) Not the 14.7 it was at.

I’ve been struggling with the closed loop setting and Spunkster had come to the conclusion that it’s the AEM X Series wideband, and maybe so... when in closed loop, and this is happening, the S. Trim will show that it’s compensating -18% to keep it at 14.7.

I’m at a loss, so any suggestions or advice would be greatly appreciated.

Thank you.

It's fairly normal for the fuel trims to change a lot at idle, even on a stock vehicle. Temperature changes are the main cause.

Check you injector dead times are correct. To do this drive at a steady speed and very slowly reduce the throttle until the injectors cut out. The fuel trims should stay flat otherwise the injector dead times are not correct.

Check your cooling fan is grounded correctly so that when it comes on the voltage does not change.

But if your AFR is changing from 14.7 this would imply that the fuel trims are not working. A calibration and datalog would be good.