2G Built motor and flex fuel

[AWD-Tony]

I don't know for certain but this sentence (we've both quoted the whole page haha) leads me to believe the minoct is the lowest you can go even if both tables are the same:
This adjustment is done by monitoring knock retard (the amount of ignition delay added in by the ECU in response to knock sensor activity). More detonation means more knock retard and a lower “value” for the ECU's fuel octane rating."
I interpret it as thus: knock picked up by knock sensor creates knock retards which leads to a lower value of octane rating. Lower value of octane rating means more aggressive interpolation with minoct table.

I know right haha. I’m reading that as it’s the way the ecu figures which tables to use. Anyone have Tom on speed dial

 

[1990TSIAWDTALON]

Well Nick, when I looked at the log, if it said it was pulling 10* and I looked at my timing table vs what the log said, it did indeed pull 10*.

 

[Vegas Smith]

Well Nick, when I looked at the log, if it said it was pulling 10* and I looked at my timing table vs what the log said, it did indeed pull 10*.

Lame, that means you were only running 20 degrees of timing

 

[1990TSIAWDTALON]

Lol, you know it!!!! It has been a few years, I will see if I can find an old log (I keep them all, surely I can find ONE) and review it to see if I'm just crazy (NO REPLIES NECESSARY......)

 

[Kevin Jewer]

The Minoct timing table is the lowest timing that the ECU will target, but not the lowest it can run. Knock Retard will still reduce timing below that, if activated.

To put it another way, you can think of Knock Retard as a short term knock trim, and the Min Oct table as a long term knock trim. Knock retard timing will always be removed from the current timing target, instantly, no matter what (this is nonadjustable in ECMlink, though you can ignore it two different ways). As more and more knock is registered in some time frame, the Octane value (mentioned and explained previously in this thread) is reduced, shifting the target timing value more toward the Min table. This semi permanent reduction in timing should reduce knock activity and therefore Knock Retard incidents. Eventually, if knock is common, the ECU will settle on some octane value between the two tables that works.

That is stock operation though. With ECMlink, since version 1 probably, at every Key On, Octane is reset to 255. So, the stock functionality is mostly defeated and we're just left with Knock Retard. Since people with DSMlink are generally running good fuel, a reasonable tune (hopefully), and keeping an eye on things, it's not a problem. And this is why many people just set the min octane table to match the max octane table. There is really no harm (or benefit) in doing that, since the min octane table is effectively defeated with ECMlink. The upside is that this table is freed up for switchable maps, flex fuel, and other cool shit.

To tie this back into the flex fuel discussion, you can indeed set the min octane table to the timing you want on straight gasoline, and the max octane table to the timing you would want on E~85, and let the ECU interpolate in between. It works great. And you still have Knock Retard working as it always has. As a general statement about ECMlink's implementation of Flex Fuel, it works brilliantly. The only thing it doesn't adjust for automatically is boost, which I've never found to really be a problem.

 

[1990TSIAWDTALON]

Dam, thanks Kevin. Your expertise is ALWAYS appreciated! Thanks for chiming in!
(I love my tuner )

 

[gst-turbo]

Thanks everyone for the info will be adding a flex fuel sensor, can’t wait to get my motor back from the machine shop to start playing with ecmlink