Likely a knowledge gap on my part, but I’m trying to understand why the Lamba isn’t hitting target with Short Term Trim enabled. I noticed this only after I went from 10% ethanol blend (pump 91 locally) to an 80% Ethanol content (added 35 liters of 85% Ethanol 117 oct blend to tank which was about 1/8th full).
Setup - Audi A3 8P 3.2 VR6 Turbo. Flex fuel sensor installed and configured. Fueling is set to reference Flex fuel sensor.
My rough understanding is that for the most part, I shouldn’t have to change my VE table when adding Ethanol. the Ethanol Correction table should add fuel based on Ethanol content picked up by the sensor. That all seems to work correctly, however when I’m on boost, at or around 100% TPS, the fueling doesn’t correct (Short term trim) to meet the target as I would expect. It consistently stays under the target by about 10-12% (Lambda error Mult.) I even adjusted the Ethanol correction table up to 50% correction (from 36.8) at 80% Ethanol to see if it made difference, and if it did it was very minor.
Is there something I am missing in the Config? I’m attaching a couple logs and my Config that was used for the logs. I’m not new to the product but haven’t had the chance to start adding Ethanol in V3 until this weekend and was concerned with it not even trying to hit target. Perhaps it is due to my Kp and Ki scales?
In any case, I appreciate any input from @Jadzwin_ECUMASTER or the other seasoned pros in here.
configs and logs attached
E85_missing_Target.emublog3 (21.2 KB)
E10_hitting_target_mostly.emublog3 (14.5 KB)
Beta_V3_357_post_e85_add.emub3 (70.8 KB)
Hi,
if the short term correction just corrects up to a constant offset this usually means ur I portion of the PID is too weak.
But in ur settings i first would try to increase ur P portion….cause it seems to be very very low, which results in a bad reaction of the controller.
I would first invest some time to tune ur shorttermtrim PID in general und then see if ur ethanol issues are still present.
That is good advice. I can’t say I’ve ever spent time tuning the PID on the Short Term Trim. I’m not even sure where I would have gotten the values (maybe my V2 tune or an early V3 base map from Jadzwin)
I’ll see if I can’t get the P and I values dialed in a bit better. I’ll see if its available to log in the PID monitor.
Thanks for the input
I just had a look on ur log. Ur short term trim is reacting ultra slow. U start from cruising point with around -9% correction and it takes more than 3s till the integral goes down to 0 although u are far above the target in the fullload phase. So it is reducing fuel while fuel needs no be added….ur short term trim is ur enemy and not ur friend 
I would start at least triple ur P portion to around 12-16…but also give the I more power…that should change a lot in ur fueling.
I made the adjustments you recommended while doing some logging. Seems to be better. I also decided I wasn’t going to chase my tail and adjusted the VE table to suite the target. I know the STT isn’t a tuning tool and if the Ethanol correction and STT were not getting me close then I went with the traditional approach and dialed in the VE table to match the target. I would rather work back with the Ethanol correction table than make a mistake while i’m pushing it on the dyno with the Ethanol. So, The VE table is dialed in now and when I go back to 91 I’ll see what the VE looks like on the other end. If its too rich then perhaps I’ll need to run 2 tables and a blend vs relying on the Ethanol correction with all the various fuels/concoctions on the market.
we don’t have Pump E85 where I live, so its barrels of Ignite or Ethanol one that we source.
Thanks again for the Input.