I did cams in my 2015street glide and have done a few AT. I get to a point where I am asked if I want to cap or scale because I've exceeded the max ve over 125 were found.
should I cap or scale the tune?

 

Here is some info from an advanced user manual for Power Vision that I am working on:

Q) What is Cap or Scale and what should I select?
A) When you export your learned corrections with Auto Tune and it asks you to cap or scale this means that there is a cell or cells in the VE tables that are at or have exceeded the high limit of the VE table of 127.5. If you select Cap it will “cap” the cell(s) at 127.5 and correct the rest of the VE tables based on your Auto Tune data. If you select Scale it will raise the displacement constant (cubic inch) within the calibration and then normalize (lower) the VE tables. Choosing Cap or Scale will depend on not only the amount of cells that are maxed at 127.5 but also the load range they are located. If you have only a single cell or small cluster at 127.5 in most cases we would recommend capping, especially if the cells are in the lighter load or decel area. If you have a large cluster of cells that are maxed or of they are in the higher load or WOT areas you may need to select Scale. Some important considerations when scaling; you will want to have as much data as possible before selecting scale as the entire VE table will be changed and normalized for the difference in displacement. In some cases depending on the amount of correction and the data itself it may scale excessively, this can result in an abnormally high displacement constant and abnormally low VE tables. Generally speaking, most scaled maps on mildly modified motors should be within 10-15 CI of the actual engine displacement, however it not uncommon on extensively modified motors to end up the CI in the 140-150 range.

 

There are some recent FAQ guides on the DJ website one of which covers that very discussion and they agree with what you just said as well.

Remember to use the mode selection button on the hits screen, within the autotune process, to see how many and where the max cells are.

 

Personally I think it is more complicated than that. CDE/EGR can smooth out some of those peaks, timing can make a difference and you have to collect data using SMOOTH throttle movements (that last one we are back to ultimately best done on a Dyno, by a pro).

My Ported 57H and ProPipe doesn't have any scaling ...does that mean it must be rubbish?

 

Jamie,

Most of this makes sense but I have to ask.. How likely is it that cells max out the VEs in light load or decel areas?

Bruce

 

Light load? Not if you have good sampling and the EGR tables are adjusted correctly. High VE's during decel? This does happen but this is where understanding comes in. Most of the time this is because of reversion. Fresh air being read by the sensor. It doesn't know any better and just reports lean. Auto programs just see a lean reading and add fuel. Usually you can take this high VE area and blend it with reasonable VE numbers around these high cells and the bike still won't pop. Sometimes you do need to add to the VE's but I haven't had to add enough to hit 127.5.


Auto programs are great but I rarely see them work 100% of the time. The human factor still goes a long way.