open loop tunning

[aaronr]

For some reason my short fuel trim start working when come to complete stop or at an idle. I'm not turning some thing off. They don't come on when i driving down the road.
Here is copy of my tune and lof file.

[WeathermanShawn]

I take it this is a COS?

[aaronr]

yes it is. "cos3"

[joecar]

Hmmm... curious.

[aaronr]

Any thoughts why this is happing.

[WeathermanShawn]

Well, I don't pretend to be an expert on COS..but it seems like problems like these usually have to do with 1 of 3 things:

1. Commanded AFR (stoich or non-stoich).
2. Trims enabled or disabled
3. How STFT's are being applied. I.E., why at Idle not cruise?

Is this a new occurrence?

[aaronr]

1. set 14.71
2. trim are disable
3 Still tring find out.

[BlackGMC]

It appears B3607 is the issue. It is limiting the commanded AFR at idle, that limit is set at 14.68 which is the same as B3601... IMO that is what is causing the triming at idle only...

[WeathermanShawn]

It appears B3607 is the issue. It is limiting the commanded AFR at idle, that limit is set at 14.68 which is the same as B3601... IMO that is what is causing the triming at idle only...

That sounds very plausible..

[joecar]

+1.