V.E. Air temp trim

From the help .pdf..

"V.E. Air Temperature Trim Table – This table allows for a fuel trim multiplier against air temperature variances from what is read at the air temperature sensor, and what is actually entering the Engine. This table is NOT the part of the fuel calculation in the Speed/Density equation, but a separate trim for variances."

So recently I spent some time tuning on the dyno, got everything dialed in, it was 95 degrees that day, and my Intake air temp readings were 134-139.

I've now done some logging here on some cooler days, (air intake temps are around 104-107)and compared it to that day. it seems like in the same tuned load cells and target afr's, I'm getting a bit richer output, almost a half point. The idle afr also seems a bit richer. My VE Air Temp trim table is zeroed out flat.

So my question is, with that table flat does this seem like normal behavior, and if so then I should begin modifying the table based on this information?

by the way, this is E85 fuel also

gbennett wrote:

by the way, this is E85 fuel also

...

Admin wrote:

gbennett wrote:

by the way, this is E85 fuel also

...

eventually got it figured out, and also car is more of a toy now and not my daily drive year round in Michigan weather so that helps.

What did you end up figuring out?

Tuned car in one temp, noted where it it was on this table and set it to 1.00, finished tune. When temp changes a lot, check this table and all afts, change if needed for current temp and interpolate.

*afrs, sorry replying from phone

The fueling should not be affected by temp in that way. The VE calc takes temp into account. There may be an issue with the accuracy of the airtemp sensor. Where is your temp sensor located and which sensor are you using? Also where do you have it wired in? This can also be cause by other issues in the map, perhaps there is something else not setup correctly. Id say lets explore the airtemp first and go from there. U should not need to add trim to that table.

TunerChris wrote:

The fueling should not be affected by temp in that way. The VE calc takes temp into account. There may be an issue with the accuracy of the airtemp sensor. Where is your temp sensor located and which sensor are you using? Also where do you have it wired in? This can also be cause by other issues in the map, perhaps there is something else not setup correctly. Id say lets explore the airtemp first and go from there. U should not need to add trim to that table.

I'm using what if I recall might be the AEM air temp sensor, it's mounted a couple feet down before the TB, after the FMIC. However, I don't have much built into that table at all now, maybe, 0.99 to 1, at most 2% fueling across the entire table which since I've stopped driving it in the winter, not really looking at the 40 degree and below F portion any longer.. so as you said, when it is all said and done I might be good with just running it flat anyways..

the first time I learned about this table I was actually having some trouble with the car getting really lean in the winter, bad enough to where I couldn't keep it running.. after swapping a bunch of hardware on the car out I discovered this table had a 15% tilt on it in the .srz that was in the car, I flattened it out but was worried I needed to watch and adjust for my application.

Ahh ok, well sounds like you got it sorted out then!!

TunerChris wrote:

Ahh ok, well sounds like you got it sorted out then!!

it's been good for what I'm doing with the car.. had it pretty good last year but definitely would richen up when it got cooler at night during a pull.. but would be ok at idle and driving around. honestly I've not spent as much time driving it this year, mostly drag strip days, setting up boost control, and hour of dyno rental and that's it

swapped out some parts over the winter here, new throttle body with no fiav and a different base idle set screw.. it took me a while to get that going correctly (idle offsets and then the adaptive idle table was moving quite a bit on its own until I got more base idle opened up on the throttle itself) but it's close now, just a little higher than target when it's warming up. But that is a completely different topic of course.. thanks a bunch for your time though, it's really appreciated!

If it works it works. I've found some irregularities like that and didn't have time to look into them. Using the air temp trim worked fine.