I feel like I've been spamming this thread, but I have an update.
When the front sensor is set to -8C or below, the evap purge valve PWM, after about 60 seconds, changes to 0%. Then when the front sensor rises above -8C it changes back to 3-3.5% (again after 60 seconds). The PWM value remains the same when setting the front sensor at all other temperatures (tested up to 40C). This is at idle.
So what this means is that by setting the front sensor to -8C or below it turns the evap purge valve off.
It's almost certainly a safety mechanism to avoid ice building up in the valve and breaking it, there's examples of this protection on other vehicles.
What does this mean for the bike?
The bike still has a closed loop mode, it's still adjusting the fuel trim based on feedback from the lambda sensor, so by closing the purge valve all that is happening is the throttle body is opening more, or the injectors are pulsing less.
In open loop the purge valve is closed.
- When idling there will be some oscillation between CL and OL, during this oscillation it's possible there's a 20-50 millisecond response delay of the purge valve (if it wasn't turned off).
- That's equivalent to 0-2 sparks per change of CL to OL (assuming 30ms per spark at 4000 rpm, 4-stroke, 1-cylinder)
- That's with the valve open just 3%.
- That's not including all the air from the throttle body (which presumably is a much higher ratio).
- At higher RPM and constant speed the valve should be wider open, the throttle body should also be wider open.
- At initial acceleration the bike will switch to OL once.
- There will be a response delay with both the throttle body and the purge valve concurrently.
- There might be some asymmetry in response that means 0-2 sparks of different mixture (once per change of throttle).
- Again the majority of air will be coming from the throttle body.
This is also all assuming that the evap purge has little to no vapours. That would certainly be the case if it was cold.
- Shift-Tech's product won't work when the real temperature is greater than 15C
- Functionally it does not do what a booster plug or similar products do
- As the purge valve is closed, it's likely that the evap canister will become saturated with gas over time.
- When transitioning between 15->16C you may experience sudden surging as the evap purge maybe extremely rich from build up
- At warmer temperatures any effect might be reversed (i.e. when the evap system contains vapours).
As for Shift-Techs claims in general
- AFR/header glow etc.
- This depends on the frequency of the oscillations between open and closed loop and the length of time spent in each frame.
- Let's say we spend 500ms in CL then 500ms in OL (cycling again, and again).
- Shift-Tech product would spend only 20-50ms out of every 1000ms doing something different.
- A booster plug (just as an example) you would expect it to be doing something different every OL, so 500ms.
- If the bike is oscillating every 100ms, then potentially Shift-Tech product is offering 200-500ms of difference every second.
- However it turns out Euro5 means the bike has to spend much more time in the CL than the OL. So even if it's oscillating really fast, the its not going to contribute very much at all, and that also applies to the booster plugs.
- Regardless of where you start from the number's end up being really small, like 0.x% difference.
- Better acceleration through all gears
- This is weak claim. There's a single switch from CL to OL; at best they can only ever be a 20-50ms, 0-2 spark difference, one time, when you open the throttle. Only one bang is a single digit percentage 'better', if you are lucky.
- Smoother at idle/low RPM
- Not opening and closing a valve is by definition smoother. I didn't research it, so sure why not.
Do I still think it's a scam.
Firstly I'm pretty annoyed that Shift-Tech clearly sold a product without knowing what it does. Essentially Iskandar and myself have done all the research that they should've done.
It fails to do anything whatsoever in the summer months and it's possibly worse (surging) during spring and autumn. During winter the bike might make a different noise (no air sucked through the evap valve), but you'll probably not notice the 0.x% difference in actual fuelling.
It's arguably strongest claim is acceleration performance and that is also it's weakest in terms of delivery. Over time their product page has gone from "Reduced header glow" to "Slightly reduces header glow", all because Hypermotardking didn't get the result he was expecting. It's very clear that the product is being alpha tested on users.
So my opinion is yes, it's very much a scam.
If you want to open another can-of-worms, then it's time to start looking at opinions of whether removing the evap is good or bad.
