Idle AFR on CalumRT S13

[DPS]

For some reason I can't get the AFR to stabilize at idle. It will swing from ~13.8 to ~15.3. I've tried tuning it with and without 02 feedback and it still wants to move around.

With the 02 feedback turned off and the idle cells @ 0, the WBO2 reads ~13.4 afr. I make the appropriate adjustment and the afr will move to 14.7. If you let the car sit and idle long enough it will start to wander.

With 02 feedback on and the idle cells @ 192, the WBO2 reads ~13.4 afr. Again, I make the adjustment and it does the same thing.

I have a Data Scan log at idle with a throttle blip or 2 in there. Unfortunately AFR isn't logged in Data Scan. I can't seem to attach it though. I could pm or email it if someone was willing to take a look.

Thanks,
Brad

[dfddfd2]

Are you using the simulated narrow band output from the WBO2, or the stock O2 sensor as input to the ECU?

Dave

[DPS]

It's the stock NBO2. I just find it strange that it has this behavior in both open and closed loop.

[dfddfd2]

I suspect the O2 sensor. Try using the NB output from the WBO2 as input to the ECU.

Dave

[DPS]

Why would you suspect the 02 if it does the same thing in open loop?

[dfddfd2]

Setting the fuel map cell value to 0 doesn't disable closed loop. What are you changing to turn O2 feedback off?

Dave

[DPS]

0038 - bit 5- O2 Sensor Flag. I uncheck the Set box and change the fuel map to 0. The data display shows no feedback from the O2 and the A/F Base sits @ 100 without movement.

With the O2 enabled the A/F Base trends around 112 and I can watch the O2 gauge swing back and forth in Data Scan.

[dfddfd2]

It's normal for the AFR to oscillate around 14.7 with a narrow band O2 sensor, although yours seems to vary more than usual. Your NB sensor may be slow to respond causing greater swing before changing direction. Vacuum and/or exhaust leaks can also cause unstable AFR readings.

Dave