Just to kind of finish this off...

• 5 "autotunes" taking logs at the same time
• 5 good log runs collecting as much varied data as possible, especially higher MAP in the lower revs (sorry but either the PV or the autotune program just isn't stable enough for me to get good data ...I personally think both actually)

For each of the above...

• From the log, use MLV (or Excel) to create a CDE aligned VE(MAP) table so I can see the 50 and 60 columns
• For each cell in the CDE tables calculate a New CDE...

• if autotune, then leave VE tables alone (the next autotune would only mess them up anyway)
• if logging and MLV, use MLV to create new VE tables and update config for next run
• if logging and MLV, start addressing any spark knock
• If necessary ...Update CDE tables
• rince/repeat

My VE is now 0 or 1% (with an odd 2 or 3) between data collection logs

So each iteration of CDE tuning seemed to get the numbers closer. The big %age changes earlier in the tuning settled down to 5% or so in a couple of cells by the 8th iteration. So that was the point I stopped changing them.

The last 3 log runs the VE(TPS) was stable but the VE(MAP) was still wobbling around in the 40-70kpa range and one run the 60-70 would be 4 VE the next it would be -1 ...that was as close as I was going to get. Incidentally, most all of any knock is gone.

She runs pretty darned good, still a slight stutter/surgy instability under 1400 but that, I have decided is nothing to do with VE tuning.


[The mods can take this comment down if they wish but I, personally, with no axe to grind anywhere, think there is something slightly strange with MAP and MAP sensor voltage on the Power Vision. It seems to be getting in the way of me getting it any closer]

 

The VE tables now look like...

 

They say that pictures are worth a thousand words...
This shows the overall change of the starting point to the finishing point for the CDE and resulting VE table...

(remember the CDE and VE table rpm Y axis are different)

 

Didn't CDE are supposed to have no effect above 60kpa ?

 

What this shows is overall changes. This includes the regular changes that come along with mapping VE's as well. BUT it will absolutely have an effect over 60kpa. Two things can come into play. A cell is affected by surrounding cells and adaptive table layout.

 

Jason is right ...you have to remember that this is street tuning, never the same run twice, and with a Power Vision ...you simply never get the same results twice so pretty much ignore anything less than 5% different

What he helpfully didn't point out is this though...

If the 60 and 70 columns pretty much never change, the idea of comparing and calculating a change based on this two numbers is complete blocklocks!

So under the heading of this is me just wittering on about something no one really cares about, I have amended my idea to look at the 50 and 60 columns (so have edited the formula above)

(having read a pile of V8 tuning stuff about stuttering and surging, one of these days someone is going to tell me to shut up ...it's nothing to do with CDE, it's about timing tables )

 

So, do you guys have some news about the CDE tuning ?

 

Hi Frederic
I've tried this about half a dozen times now, using different starting points in both CDE and VE tables. I pretty much always seem to end up with the same result.

The shape I end up with, I'm wondering if is a general V-Twin thing, rather than specific to the cam/exhaust I have. I'm beginning to wonder if CDE really matters short of having a general shape to your table.

Dynojet UK offer dyno tuning services here in the UK and I'm trying to work out how much they can cover (really spooky ...they just sent me an email as I was typing this). There is another shop a lot more local that tunes race Ducati and have done a couple of Harley, so may look to trying them.

 

Gordon,
Would you please explain the running experience you are describing.
Is the surge/miss/hesitation while taking off from a stop and feeling it?
Is it while lightly cruising in 2nd-5th gear?
Is it while trying to aggressively accelerate at that rpm?
These bikes will go lean under high load/low rpm below about 1750 rpm. And this requires a large VE in the 80-100/kpa-below 1750 to 1250 rpm area.
So, when and how do you get that stuttering?
Bob

 

Hi Bob,
The bit I don't seem able to get perfect is idle and 30-50kpa under 2k (yea I'm a fussy sod )

Take off from a stop is good in 1st or 2nd
A reasonable amount of acceleration is good at low loads, (too much is lugging and yes that will kick a bit)

I do see that high VE under 2000 @ 80-100 kpa, especially on the front cylinder

I've struggled to describe it over the last year or so but reading others peoples descriptions I would best describe what I think I am chasing as an intermittent miss, possibly only lasting a single cycle, maybe something like once or twice a second but very irregular.

Tuning CDE does get it much better (hence this thread) but I think I've reached the max of my ability without a Dyno.
Gordon