question in regard to s14 VE map (ka*t)

[highoctane]

To start off, I'm very new to tuning so I'm still in the leaning process so please bear with me. I've been trying to find some info in regard to the s14 VE map but with no luck. Went through the Nistune printout but didn't come across a writeup in the matter. Hoping someone can shed some light for me. From what I've read, people just tune the fuel map and leave the VE map as it.

So if you just tune by the primary fuel map (copy over to knock map, unless you run a conservative knock map for safety reason). Do you scale the the tp scale in the VE map to the same scale as the fuel and ignition map? Or just leave the scale in the VE map alone as it is from the factory?

During cruise, the ecu is in closed loop getting feedback from the o2 sensor. When/what interval does the ecu kick over to open loop? I know it is in the high load cell, but I'm unclear as to when it actually switched over.

I though that I have gotten the k and latency down already with the cruise and idle, but just in certain spot of the map it tend to go lean or rich depending on the area. Under the fuel map viewing as target a/f ratio, I've set the desired a/f, but during logging with the wideband. That area is not meeting the desired a/f as entered in the cell.

Thank in advance and sorry for the long post.

[Matt]

Its basically a trimming map used in conjunction with the fuel map. From what we have found is that VE does adjust your injection pulsewidth like the fuel map does. However it seems that its used to tune in conjunction with your ECU AF Alpha feedback gauges.

I peronsally havent had a chance to experiement and document it properly on the R34 but was something we were going to try with next time on the dyno.

[highoctane]

Its basically a trimming map used in conjunction with the fuel map. From what we have found is that VE does adjust your injection pulsewidth like the fuel map does. However it seems that its used to tune in conjunction with your ECU AF Alpha feedback gauges.

I peronsally havent had a chance to experiement and document it properly on the R34 but was something we were going to try with next time on the dyno.

Since this is tune in conjunction with the ECU AF feedback gauges, I need to rescale the tp value in the column to the value that I'm using in the fuel map and ignition map? Then just adjust value till I need my desired a/f?

I'm unsure of what to do with this map for now as far as tuning goes. Thank you for your help.

[Matt]

you will notice the stock scaling for this map fits inside the fuel map, mainly around where it is 14.7:1 so i would adjust the scales to fit in the new map similarly

[tastyratz]

I wanted to bump an old thread with a good question. I have been trying to tune via VE table and it does not seem to really make any difference?

Do we 100% realize exactly how the ve trim table functions?
Are there instances where it is disregarded as a function, such as with the o2 turned off/ unplugged/ tps idle switch engaged, etc? Only in cells with 14.7 target?

Is it fully linear in function multiplying in the inverse? for example... would a fueling of 8ms and a ve value of 100% I get 8ms fuel, a ve value of 90% = 8ms * 1.1 for 8.8ms, or a 10% increase in fuel?

I can't seem to get it to work, and part of that I think may be my lack of understanding on it.

Can I also perform math against my map to manipulate either value? For example... if I know 1 cell is tuned to 11:1 but says 10:1, can I reliably calculate the difference, change the VE by that much, and set the cell to the correct number? Basically translating an autotuned map to a ve profile or similar.

Can I for example, set my fuel map to 12:1 across the entire board, then tweak the ve table so that each and every cell results in 12:1? Would that map out a proper VE profile for my needs and be the best way to go about it?
I wish ve was handled by autotune...

[Ligouri Rd.]

I realise this is probably way late for the previous poster, but I have managed to tune successfully by using the VE map.
My Primary fuel map is set up for what I like to consider my ideal fuel ratios. I then adjusted my VE map until the the real world AF values matched my fuel map.

It did take quite a bit of adjustment to the VE map to get the real life AF values close to my ideal. You can see the green valley in the VE table in high rpm/tp regions where i reduced the values to lean out the fuel. Before adjusting the VE I was considerably richer in this area...and it is still a little richer than what I would like.

However after reading Matt's earlier post that states that the VE map fits inside of the primary fuel map, I may be using the VE map incorrectly.