VersaTune User Forum

Hi all,

Targeted at Versatune developers moreso than community members, but if you'd like this support too comment below,

It doesn't look like we're able to modify what range the trims are allowed to be in. Almost all aftermarket ECUs provide this option in their closed loop settings, and while I'm aware that you can only work with what's available in the stock hardware, support for custom trim ranges would be much appreciated.

Is this a feature that would be possible to add?

Sorry if this is a stupid question.

But why would you want this?
What is the use case?

The way I see it, especially on the renesis if the ECU wants to add fuel let it add fuel.

I wouldn't want to artificially handicap the ECU from adding more fuel trims.

I guess tho ... I could see the use in preventing the ECU from removing fuel.

That could be handy.

Yeah, my use case is basically I want to disable negative fuel trims as a safety when I swap to forced induction

Thanks for the reply.

If it helps at all, you only need to worry about it in Open Loop.

If I recall it takes quite a bit before it even changes by 1 afr.

Don't quote me but I want to say something like 13% before you will see a change for example from 11.0 afr to 12.0

But I hear it would be a nice feature if possible

Yeah you're totally right, technically it shouldn't really be an issue with the correct setup.

I'd like to be able to run a draw through MAF like stock, but have the freedom to both recirc and atmo my bov safely without having to mess with my tune and do things like disable closed loop entirely, etc (which is an option of course worst-case). Yes, I understand running rich when shifting and possibly during partial throttle is silly. If we're going to play the efficiency card, a rotary forum probably isn't the place for it It'd just be nice to know that I'm not in any danger of lean spiking due to the trims swinging. I'd like to leave closed loop enabled though, less for economy (as the swinging would probably clear it) but more for just in case I encounter an vacuum leak or other piping issue as there are no safeties inbuilt and it'd be an additional indicator that something is up alongside the AFR.

Of course a standalone will always be better in these cases, but the OE ecu is pretty competent as is, realistically only missing this one small feature for my uses personally. More options for safeties would be nice as well but I'm aware that we're mostly confined by the OEM functionality. I figure exposing these four(?) values (if they can be found) would be useful to some.

EDIT: after doing some further research, it looks like a properly configured blow through setup has no downsides and is preferable due to the way the intercooler interacts with the system, so I might just proceed in that direction anyway.

you can disable closed loop altogether and than no trims will be built. that wont help with a vacuum leak but that is not often a concern. and a boost leak will only make it richer.. used that when wanted to run 16.5 and leaner AFR for low load (closed loop maxes out at 15.xx, lambda 1.05 )