extream ve table

[stv firestarter]

i have looked all through the manuel and cant seem 2 see any thing about scaling the ve table

[fiat132]

i tried the same thing and all the numbers went crazytoo????

[stv firestarter]

if i get it sorted i let u know and if anyone can help please leave step by step instructions thanks im a megastuck


steve

[newtyres1]

You're right, the info is a bit difficult to find, and there's not much there.

I just tried to rescale my VE table in Megatune 2.25, it seems to work fine. Go to Fuel tables/ve table 1/tools/ VE specific/ reset req fuel (as you did before), and put your new req fuel value in the lower box and leave the check box ticked. When you click on OK all the VE entries will be scaled down (if your new req fuel value is larger than the old one) and the engine should run exactly the same, just the VE entries will be smaller. Then go to the Constants page and verify that the req fuel value matches what you put into the new req fuel box on the VE table 1 page. Then save the changes.

Ian.

[stv firestarter]

yes id already done this but reading mega manuel it says.


Note: If you do not use the “correct” REQ_FUEL value, the VE numbers in the VE table will be skewed by the amount REQ_FUEL is “incorrect”.

so i thought it was wrong and changed it back how confuseing is that manuel

[newtyres1]

OK, it doesn't really matter...you can have a higher req fuel with lower VE entries or vice versa. The idea of a "correct" req fuel is so that the VE entries reflect the Volumetric Efficiency of your engine in percent, but that is not necessary to make your engine run well. My VE entries range from 21 to 173 running alpha-n, naturally aspirated engine. An example of a good VE table with "correct" req fuel is the one given in the manual. The fact that "the VE numbers in the VE table will be skewed by the amount REQ_FUEL is incorrect” doesn't stop Megasquirt from injecting the amount of fuel that you ask it to inject. Hope this helps. Also I think Lance should be thanked many times over for writing one of the most comprehensive manuals ever on EFI, if it is a little unclear on this point I think we can forgive him

Ian.

[fiat132]

but if i alter my req fuel then it would be the same as changing injector size and so on.....it would alter alot of things.....
i dont get it any more....i went to the menu u stated and made a change that made my table seem more realistic...but the car wouldnt run unlesss i raused all the values back to the same numbers.i am starting to get lost here.....isnt req fuel like a very special thing....and changing it would change the whole performance of the engine
i made alot of changes and now the car wont run...i even tried scaling the table from the tools menu but everything went crazy
whats the difference between scaling and sesetting the req fuel...to me it would make sense that scaling is what should be done to alter the numbers.....
i am getting lost here.....anyone....??????

[jsmcortina]

Maybe best to start again?
Set the ReqFuel as per the Megatune calculator. Then let Megatune Generate a VE table for you, then start tuning.

Ordinarily there is no need to alter the ReqFuel again unless you change you injector size.

James

[stv firestarter]

i have just tried 2 start again and my new ve table all the binns are squashed at low end of kpa am i doin somethin wrong i entered 20 kpa at idle and 200 kpa @2750rpm 200kpa@6750 and red line 200@700 on a 115cid can someone try this an tell wot happens as i had a ve table already on my pre built kit

thanks steve

[jsmcortina]

Hmm...
You didn't say what torque and power numbers you used. I made some up and tried the generate table and it doesn't look unreasonable.

Are you _really_ idling at 20kpa ? That sounds extremely low, my car idles at more like 50-60kpa.

James