Does MS2 depend on O2 sensor signal at all?
 

Since I can't quite figure out a couple issues with my '2000 NB with MS2, here's a specific question Does MS2 depend on any signals from O2 sensor?

The car has a wide band O2 sensor in it. The idle oscillation started about the time that header was removed for some re-welding. I'm grasping at straws here, but if it's reading the wide band O2 and it or its wiring was somehow damaged... Or is wideband only there for initial tuning?

It depends on if you make it depend on the wideband signal. Fuel correction depends on an active reliable wideband signal and if the settings for fuel correction are not that great, it *could* lead to oscillations at idle or otherwise.

EGO control (which can be disabled) and the VE analyze stuff uses it. Don't technically need it to run open loop.

OK, thanks!

Is there a way to check in Tuner Studio if wideband is still good and its signal is still OK? Specifically, how o check for fuel correction? I have a couple logs in another thread, anything can be seen there?

The fuel correction is called 'EGO correction', if looking in logs or on the dashboard. What wideband are you using?

The wideband is Innovative LC-1.

I just checked and EGO correction is set to the following:

EGO Sensor Type: Single Wideband
1st EGO sensor port: Local
Ignition Events per step: 20
Controller Auth -/+ (%): 5
Active Above Coolant, F: 60
Active Above RPM: 850
Active below TPS (%) 70
Active below MAP (kPA): 850
Active above MAP (kPA): 22.00

WB Controller Settings
Algorithm: PID
PID Proportional Gain (%): 20
PID Integral (%): 20
PID Derivative (%): 0

Also, looking at the log files, like the ones attached, I'm seeing that AFR at 7.4 and it doesn't change at all, Does it mean that wideband is dead and/or not sending info to MS?

Dead or not properly connected. AFR 7.4:1 corresponds to 0V for an Innovate wideband (LC1/LC2/MTX-L). Do you have an o2 gauge (integrated with or connected to the wideband controller)? If that one works, it's the connection between the wideband controller and megasquirt that is bad or improperly set up.

Don't have a separate gauge. I was re-reading LC-1 manual yesterday and it got me thinking, I'll look at the LED and see if it's blinking, indicating fault. I'll also try to re-calibrate the for heating element and free air, as they recommend doing it pretty often (didn't realize that). Will also check wires to and from controller. There's an analog output on the controller, so, in theory, I'll be able to check with a voltmeter on that brown and/or yellow wire.

Here's a funny thing. i have a log from 2014. The AFR is flat at 7.4:1 as well. And the car was not cycling idle back then. So that's a little weird. The initial logs from 2012, when MS2 was installed, show varying AFR, as expected So it's possible that LC-1 went bad long ago and I did not see any effects and idle cycling I'm seeing now is something else. But at least it forced me to dive deeper into trying to understand MS2. Which... I still don't :) So if there are any other ideas or checks to perform, I'd love to hear them.

Thanks again, gentlemen, your help is really appreciated! I'm trying to learn. And remind myself of my EE degree from 25 years ago.