VS S3 Manual Log - Problems Or Normal

[Monarols71]

Not holding my breath that it will be fixed, it might but not that hopeful Was just something I noticed in the log you posted that needed a tweak to get back in spec before trying/adjusting other things like yoda mentioned.

We can breathe easy. You were right. It's not fixed. In fact it seems worse. Had to push the clutch in in slow traffic as it just wanted to bolt away with no throttle, It was about 1700-1800 RPM before it settled after a few seconds.
I thought I had a log of it, but I didn't know the bloody laptop stopped working when you closed the lid
Oh well, I guess I'll try and decrypt your message and go over the log again. And don't hold your breath that I'll find it.
Thanks

[Monarols71]

I have NFI. I'll take an old school educated guess, and I'd guess it's leaning out for some reason.?

[VL400]

If you can get a log of it again it might be possible to see what its going on.

[Monarols71]

Lots of logs, but finally got one of what it seems to do, the only difference is I stalled it this time.
The log is a bit long, but around 1.16 is where I stalled, right foot on brake (to stop car from rolling in car park) and clutch in and restarted at 1.18. At 1.28 she'd finally settled down (the car, not the wife) and we could go again.
Hopefully this info is what is required. Is the AFR meant to jump up and down like it does, or is the O2 sensor not right? Or something else.
Kind Regards

[VL400]

The oxygen sensor looks a little lazy actually, it should swing rich/lean during closed loop but is not getting many cross counts. Next time your going for a longer drive see what it does sitting on the freeway - should almost look like a sine wave. The Long term fuel trim (use the right hand as it only has one sensor) is pulling a fair bit of fuel out too. Maybe try resetting the PCM, and if your keen, disconnecting the oxy sensor to run open loop with no correction and see if it improves. Could also try cleaning the IAC, maybe its all gummed up with carbon and too slow to react.

[Monarols71]

Thanks VL400.
So what your saying regarding the O2 sensor, is that it should run in an hysterisis (what I call it?) type mode. 14.6 is the ideal, but it will swing between 14.5 and 14.7 (say) constantly to keep it where it should be.?
We have new ones here (4 wire V6) that should be the same , and I'll put one of those in.
I'll reset the PCM in the morning, and clean the IAC when I come back from the dentist.
We'll see how we go after that. Back to work Wednesday. And the daughter will probably want her laptop back.
Thank you for all your efforts.
Cheers

[VL400]

I would go for a drive first before just changing it out, need some steady driving to be sure and the last log was more stop start stuff. And...just looking at your first posted log here is what it should look like with a good number of cross counts, bottom monitor blue trace...

OxySensor.jpg

[Monarols71]

Back again after our ISP had a server down the last couple of days.
Thanks VL400.
Check this out. Both are from the same log. Something is very much awry.
Same revs, different speed because of the limits, but WTF.

[yoda69]

The top plot the vehicle is obviously in Lean Cruise as it has a target AFR of 16.3, hence the O2 sensor reading down at 53mV, in the bottom plot the target AFR is 14.7 (Stoich) so O2 sensor is rich/lean toggling as expected.
yoda69

[Monarols71]

Thanks yoda69.
That can happen any time during highway driving depending on certain conditions?
So the car can be in lean cruise, then when overtaking it goes stoich, then back into lean cruise again when everything settles and conditions are correct. Is that right??
She runs like a dream most of the time, just this very occasional "stuck throttle" type syndrome around town at low to idle revs.
Thank you all for your help. I'll keep trying to learn and nut it out.