Rising AFR Sending Issue - Any ideas?

[flightlead404]

I've been struggling with a weird AFR sensing issue. I'm 99% this is a sensing issue not actual AFRs.

Symptoms:

When I start the car, or when I jump my relay to power the WB02 system I get the initial low/high calibration outputs as expected.

When starting the car I get expected AFRs showing in Tuner Studio.

As the car heats up, the control pressure changes, raising my AFR from 10.5 ish at a cold start, to about 13.8 at idle.

But then they don't stabilize, they keep climbing, and climbing, until they are off the scale lean. The car idles quite happily and drives like a scalded dog. The primary reason I think its sensing is that the idle never changes as the AFR increases from mid 13's to past the point when I don't think the car would even idle. (FWIW the car was tuned with an external WBO2, and I'm not running anything closed loop).

Now, here's the weird thing. I'm currently using a 14Point7 Spartan with a new sensor. But I've got a new Ecotrons controller as well, and it does the same thing. I've also purchased a new sensor of Amazon and it also does the same thing.

I was pretty careful with the wiring, I know the controller, and therefore the sensor, is getting good +12v and has a good ground.

Could this be something with the MS? The changing indications with temperature would point me to the MicroSquirt, or to a bad ground, but all my other sensors are rock solid.

Any clues or ideas would be appreciated.

[flightlead404]

I just wanted to close this out, although it didn't get much interest lol

I have three WBO2 controllers and two sensors and playing swaperoni with them all clearly showed that all controllers and both sensors displayed the same behavior.

I even isolated the controllers from the cars electrical system using a standalone battery, and from the MS by just measuring voltage.

Give the above it was clear this was a "car" issue and not a controller issue or a sensing error per se.

What was throwing me was the mixture indication was slowly climbing even though the car didn't appear to be idling any differently.

Ultimately what I discovered was that I had incorrectly set up the warm control pressure in the base control pressure map portion of the settings. I had set it to 315 kPa instead of 365 kPa. This resulted in a grossly rich mixture that I had then attempted to reduce again with the idle mixture adjustment. The car was still idling super rich, and so rich that the sensor was actually interpreting this as a significantly lean mixture. This is also why the sensor appeared to work once off idle, because the grossly over rich issue goes away above around 1,500 rpm.

Anyway, properly setting the base warm control pressure fixed the mixture sensing issue at idle, and has made an already nice idle even smoother. Idle mix now properly at around 14:1.

Now I have to go back to the dyno to re-tune for any changes the control pressure would cause, and also to account for my new 1.0 wastegate spring.

[smurfbus]

Didn’t it smell gassy with false lean? Iirc innovate logs show rich lean spikes or used to but not sure about the quality now that it totally different company/business

[flightlead404]

Originally Posted by smurfbus

Didn’t it smell gassy with false lean? Iirc innovate logs show rich lean spikes or used to but not sure about the quality now that it totally different company/business

It always smells a little gassy, and it was smoking a fair bit too which should also have been an indication.

My problem was being lured by the siren of technology. I should have gone back to basis, ignored the electronics, and then I would quickly have realized what the issue was.

Lesson learned. The old ways are often still the best