XFI fuel corrections at WOT

[MSDGN]

When making fuel corrections in XFI at WOT I would assume all the tuning is done in the VE Table...basically just modify the values in the cell where the green ball is and some of the surrounding cells also...again I assume you adjust the values to get as close as possible to 0 for O2 correction...so let's say at 5500 RPM...my actual A/F ratio is 11.5 and the O2 correction is 7% then I would want to increase the values in the cells by 7%...is this right?...should I ever tweak the settings in the A/F Table itself?...

 

[bobc455]

You are doing it all correctly!

You don't need to tweak values in the A/F table.

If the O2 shows 7% correction, I would start by making a 2 or 3% correction to the VE value then trying again. If I change the value by the amount of O2 correction, I usually find that I've gone too far.

-Bob C.

 

[MSDGN]

What's a safe A/F ratio at say 23-25 PSI boost and 6000 RPM?...the 11.5 I saw at 5500 RPM's and 20 PSI boost seemed a little on the lean side...

 

[d90dan]

Scott,

I would get the XFI pulling fuel ASAP. Here's my reasoning:

Since the O2 is reactionary, your motor has already been lean before the computer has added 7% fuel to reach 11.5. If it's pulling -7% then it would mean the opposite and your reducing the amount of fuel to get to 11.5. 7% shouldn't be a huge deal but, as I'm sure you know, going lean breaks stuff quick at your power level.

So in your example I'd probably make a bigger jump and add ~10-12% in the appropriate cells. Then continue making passes and tuning, in smaller adjustments, to zero by pullng fuel.

You would adjust the A/F table when you want to change the targeted A/F. Idle, cruise, spool-up, WOT can all be tweaked. 11.5 at WOT is probably about right once tuned, I would try slightly different A/F's and see how your car responds. I usually start around 10.8-11.0.

What's your timing set at the higher boost/rpm levels? Starting with low timing would give you an extra margin of safety while getting the fueling tweaked in.

Are you starting from scratch or did you get a base tune from someone?

 

[MSDGN]

I agree Dan...I rather go over to the richer side then come back...sent you an Email...

 

[Dusty Bradford]

When you're changing percentages you can use "shift 8". A window will pop up. 107 will add 7 percent, 93 with take away 7 percent

110 will add 10 percent

90 will take away 10 percent and so on.

 

[Craig Smith]

When you're changing percentages you can use "shift 8". A window will pop up. 107 will add 7 percent, 93 with take away 7 percent

110 will add 10 percent

90 will take away 10 percent and so on.

Yup. Also, if you hit SHIFT + 5 it will also give you the option to specify a straight percentage of change. Entering 10 will add 10%, and entering -10 will remove 10%. Same thing, but another way.

 

[MSDGN]

I know...I watched the XFI DVD...just have to get used to all these different ways to change values in the tables...