[Engenia]

The ECU should be controlling the idle speed. It shouldn't be set with the stops or any leakage past the butterflies.
If the throttles are properly synchronised, the idle mixture is set so that the engine idles smoothly and the stepper is set at the correct # steps for the ECU type, the stalling will be minimised. It can be further minimised by adjusting the idle speed in the map from 1200 to 1250 or even 1300, and the idle mixture set slightly rich.
Have a look here for a sync procedure that works for me, be aware though, that this is for a Sagem ECU. Walbros control their steppers slightly differently, so consult your workshop manual.

 

[Engenia]

.. can TuneECU tell me if the throttles are in sync or do i need to delve under there. At the moment if i slacken off the cable adjuster the bike idles, just, at around 950rpm but tends to be erratic . Do i set this on adjustments where it says target rpm or on the actual mapping.

TuneECU can't tell you if the throttles are in sync. You need to remove the airbox and get your hands dirty.

950 is WAY too low. Are you sure the stepper is even working?

In order to raise the idle speed you need to download the map from the ECU, edit the idle map & upload it. Don't do anything until you get the engine running properly though.

 

[Engenia]

.. why is it not good practice to adjust via the knob adjuster thereby leaving the butterflies open a little.

If the butterflies are open even slightly during tuning, the ECU won't be fully in control. Once its tuned, use it at your leisure, but I don't see why you would need it if it is tuned correctly.

The Tornado doesn't need (or have) the manual adjuster. If you want it to have a higher idle speed, simply edit the map. You'd only want to do that if stalling is a problem, and you haven't been able to tune it out.

 

[Engenia]

Next mod is the fitting of a pair of deep tone horns.

Need to see how you do this

 

[Engenia]

..I believe it's the ecu cannot keep up with the light flywheel effect of quickly cutting the gas?

That's pretty much the root cause. The engine can spool down very quickly. At some point the ECU must open the IACV to make it idle. Sometimes it can't do it fast enough, the engine revs drop too low and it stalls. It's a common problem with many sports bikes, even some cars.
It can be improved by running it rich at idle, raising the idle speed from 1200 to 1300 and having well synchronised throttle bodies - so that all are pulling equally at idle.
One trick you can use is to let i spool down in gear, selecting neutral much closer to idle.
Another is to keep the throttle slightly cracked when selecting neutral, and shutting it off once the revs have dropped close to idle

 

[Engenia]

Had a fiddle with vacuum gauges and Errols paper method , adjusted 2 butterflies best i could , air bypass screws don't make a lot of difference unless moved a lot. Tune ecu reads like shown, idles low on one map, soon cuts out on the other "economy"map when button is pressed which makes me think it may be a mapping issue
View attachment 39125

Target idle speed setting is a concern, if it's real. -127 rpm is a bit low ...... should be 1200
Stepper position is also weirdly low, although I'm referencing my Tornado, which is 30 - 40 when tuned correctly.

Your butterflies should very nearly seal off the throttles. Any difference between them should be corrected (synchronised) with the air bypass screws. At least one of which should be fully closed when sync'd.
Do you trust your vacuum gauges?
Have you an air leak perhaps? Ineffective bypass screws would suggest this is so. There is an o-ring at the base of each throttle that is a bitch to install properly, especially if it is reused. Or maybe the butterflies aren't sealing as much as they need to. Any air leaking past is not under ECU control.
Idle AFR should be 12-13. Outside of this the engine won't idle well. Do you know what it is?

A few notes :-

• The manual idle adjustment screw on TNTs overwhelms the ECU idle speed control. It will attempt to close the IACV to reduce the idle revs, but once it's closed, it has no more control (other than ignition angle)
• The TPS should be reset with that manual adjuster set to zero. If you don't, the ECU won't have the correct butterfly angle to use for injection.
• The paper method isn't mine. I borrowed it from Lloyd IIRC.