E10, global modifier?

[steve.82]

The UK has recently switched from mostly E5 to E10 at regular fuel pumps. To keep my fuel trims relatively low I think I need to bump a bit more fuel in everywhere - what's the tidiest way of doing this?

[wcs]

What are your fuel trims reporting?

There is a few ways to do this, assuming you have a full version of VT.

[steve.82]

+8% ish from memory. Will grab a log next time I take it out. Yep, got the full version

[mituc]

The UK has recently switched from mostly E5 to E10 at regular fuel pumps. To keep my fuel trims relatively low I think I need to bump a bit more fuel in everywhere - what's the tidiest way of doing this?

Here in Romania this change happened back in 2017 or so. The change in fuel trims remained insignificant when the ethanol content increased from 4-5 to 8-9%, I think the largest variation in fuel trims I've seen with this change was 1.6% or so. I did not even bother changing the closed loop MAF calibration for this.

And as a side note, the 95RON fuels became more knock resistant than the 100RON fuels were before the change. So now with the 95RON fuel we can 1-1.5 degrees more timing at very high boost levels (24+PSI) than we could run with the 100RON fuels before, so I imagine on an NA car this difference is even larger - for whoever will like to experiment. Yet keep in mind the rest of the additives pack may be different from region to region, so up the timing with care.

[steve.82]

Yeh I don’t know what the trims were before, could have been 6ish and the change only bumped it up a few %.

[steve.82]

I'm revisiting this and run a bit of analysis on a datalog. Fairly significant positive trims in closed loop. AFR accuracy actually isn't too bad when in open loop.

Below averages the sum of long and short trims from +/- 200rpm and +/- 0.02 load for each site, and colours it green if there are > 20 data points that meet those conditions.

Any thoughts? Which table(s) would be best to tackle this? Also why are trims retained in open loop? Is that just an artefact of the log or does the ecu actually apply this correction?

Screenshot 2022-02-23 at 4.49.28 pm.png (174.05 KiB) Viewed 4695 times

[Walle]

long term is applied to all cells no matter if closed on open loop.

this should be tackled either in MAF (as they seam grouped in "low" g/s) or in VE. you need to se the data scatter (range) for g/s X axiss and total trim on Y (scatter in sence how much of the value varies from the average by more than 2)
is your engine stock or modified, intake especially

[steve.82]

Intake is stock, exhaust is catless, pretty much stock apart from that. I am going to build a new exhaust soon so will revisit when that's fitted I think.