2003 S2000 w/ Kpro, AFRs run lean in closed loop

[liquid_helix136]

So I have an 03 S2k, the engine is professionally built by Endyn and has low comp (9.5:1) pistons as this engine will be turbo'd soon. Other than that, the car just has intake and 70mm dual exhaust.

I dialed in the fueling in open loop and using a modified version of the AP1 stock timing tables. In open loop the car runs fine, a little on the rich side (low 14s) when it gets really hot out, but at night (when I street tuned it) the AFRs stay between 14.5-15.2. However when I check the closed loop box, as soon as the engine is warmed up, the ECU starts pulling fuel, regardless of what I set the short-term trims to. The car will run in 16s-17s. I have an AEM UEGO plugged into the ELD clip, and this is what I am reading the AFRs from, (well my gauge, but they are the same in the software)

Thanks!

Here is a datalog of the condition and the calibration I'm currently using.

[Hondata]

Have you got the stock o2 sensor plugged in? I don't see any reading from it?

It also is best to set the min max shirt term trim to 0% when tuning in open loop rather than disabling closed loop.

[liquid_helix136]

Thanks for the quick reply! I checked my o2 sensor a couple hours after your response, and found that it was indeed plugged in. I decided to check the ECU harness, and noticed my primary o2 sensor had become depinned! I plugged it back in and closed loop works great now!

Also, thanks for the advice about tuning in closed loop with 0% short trims. I like that idea better.

[liquid_helix136]

Is it normal for a low voltage primary o2 sensor code to pop up when you set S.trim to 0%?

Whenever I turn closed loop on and set the S.trim to 0% that code pops up, but when I set the S.Trim to -10/10% the code doesn't show up. Very strange.

[Spunkster]

No it is not. It may mean there is a problem with your sensor.