Odd behavior

[hondaguy123]

Hi. Ive noticed a very odd behavior from the kpro recently. This has happened already with 2 customer cars. What will happen is that after tuning, the idle will go extremely lean. It can be idling at 17-18 afr and I can add 1% of fuel in and it will jump back up in the 14s afr. Then after driving very short distance the idle is back lean again. When I first noticed this odd behavior I was very clueless about why it would be acting like that. I have even taken fuel out of the fuel map while it was idling at 17-18 afr and the afr jumps back up to the 14s. Very strange behavior. Especially how I can take fuel out of the map and the afr will go from 17-18 back into the 14s. Not sure if it’s a bug or what. I have tested. This behavior happens both in open and closed loop.

[Spunkster]

Have you looked the the fuel trims when it is going lean?

[hondaguy123]

Yeap. I only let it adjust +\- 5%. When it reads lean it tries to add 5% back in. But I can add or even take away a few % of fuel and it will go back into the 14s afr. But after driving a bit it will be lean again. I even turned closed loop off and ran it in open loop and the same behavior occurs. It can be 14s afr idling and after driving a bit it will lean back out at idle and I can add or subtract 1% and afr will go from 17-18 to 14s. Even if It’s lean I can add 1% to map and it go from 17-18afr to 14s afr and I can take the 1% of fuel back out and the afr will stay in the 14s until you drive for a short distance and it just leans back out

[Spunkster]

It sounds like you may have a faulty O2 sensor as then they fail they tend to read lean.