You are correct. I was thinking of the IAT vs. Voltage table as the values get larger at higher temperature. The IAT comp table used for fuel and load correction does have a negative correction like you are saying.

It doesn't really matter either way as temps go up, charge density will go down and so will load. The mixture may be less stable at the higher temp, but it will have a lower overall peak cylinder pressure value.

On the ignition table, there is a separate IAT based ignition retard table, as I'm sure you are aware. Didn't Tephra change the load values used though on the Big Maps and set them both to baro+IAT Comp?

FWIW, I drove my car on the SD patch from ~0F to ~70F. At WOT, the same tune worked well for that range so what we are doing seems to work in practice. I drove the car at higher temps, but I had retuned for other changes at that point and tuned in the warmer weather.

 

Yep, I'm aware of the ignition retard table as well. In stock form, I just think of that as a second safety net to pull even more timing on top of the switch to uncomp load.

Yes, I think I remember that tephra did use baro+temp comp load for both maps. I think that's fine for us anyway. As least if we know what's going on and have a correction table to mess around with for higher temps, we have enough to fiddle with.

Also, I have to slightly correct my wording in my last post. My general statement was right...baro+temp comp load will go down as temp goes up due to air density going down. But my exact words that 50lb/min would be a lower comp load at 100F than 50F is wrong. It should be identical. It's just the correction from uncomp load to comp load is bigger downward correction. So, the uncomp load will be higher at the higher temp.

 

Bringing this old thread alive.

I am new to SD , using 90556701 , Patched with a 3d VE table.

I have load row x axis - 19 elements till 320 load and
RPM column y-axis 23 elements till 8000 rpm.

Can i increase the X-axis and y-axis elements in the VE table and copy over the cells ?

Will this increment throw off fueling and ignition calculations or else ?

 

bump

 

The XMLs in the 1st post are UPDATED* and can be used ?

 

i'm running the SD 2.0 live map rom 96534706 with the xml pack and all is well except for the "3k jitters"

has anyone really figured it out? i'm using the "latest" fix number 3, and still get it, i'm willing to experiment if someone can point me in the right direction. maybe mrfred or rapturd , or someone will chime in!

SD 2.0 tune has been really great, still dialing it in but the process went smooth!

 

Successfully converted to 9055 sd rom.

Logging MAP KPA using formula [x*1.6334-43.75] and LOAD CALCULATED .

MAP KPA logged is less than what load columns have been defined while load calculated is spot on as usual.

NOW , if i want to edit 3d VE map which load should i follow ?

 

Bump any one ?

 

The reason nobody answered is because your question makes no sense. If you want tune AFR by editing the 3D VE map you will need to log kPA (i.e. "follow" kPA) and then change VE % in the cells as required. Increasing VE% at a specific kPA and RPM will increase the Load, and adjust fueling using the lookup value at the intersection of Load and RPM in your Fuel Map. Decreasing VE% will reduce Load, and usually reduce fuel injected, again by lookup from your Fuel Map.

This tuning approach is only going to be useful if your Fuel and Ignition Maps are already close to tuned for your particular setup. For example if you recently changed from MAF to SD.

 

Thanks for the detailed answer.