Staintune Fuel Injection/Dobeck Performance/Techlusion Unit - Ducati

Written March ’05, Ducati based, with some info on how the idle trimmer works also.

The major problem we encounter when tuning Ducatis fitted with the newer Magnetti Marelli 5.9M ECU is lack of adjustability.  We’ve fitted lots of the Ultimap U59 replacement ECU and many others have gone the Power Commander route, but a lower cost option is somewhat lacking.  So when we had the Staintune rep down recently I got one of the Staintune Fuel Injection units (which is a rebadged Dobeck Performance/Techlusion unit) from him to try.

Given I’d never played with one of these before I thought I should prepare myself a little before I got to the dyno and wasted a whole lot of company money.  The Staintune rep had told me about a couple of websites for Dobeck Performance and, saying the .au address contained a bit more tuning info, but I still didn’t get the answers I wanted.  So I emailed Dobeck to get a clear picture of how it worked.  The first paragraph of their reply contained the line “i don't mean for the info to sound abrupt this is just what we use to combat some of the skeptics in the field.”

Which impressed me no end, but given I’m both a skeptic and a cynic it’s probably well aimed.  The info was somewhat lacking too given what I’d asked and really didn’t help answer any of my questions.  I got some more specific info after another set of very specific questions and even rang to speak to one of the people there, but it was pretty clear after this that they weren’t going to tell me exactly how it worked so I might as well just go play with it and work it out myself.

The Dobeck Performance unit is a very simple product – it can only add fuel and does so in three separate zones.  But just because it’s basic doesn’t mean it’s not valid or a piece of crap.  It just means it’s basic.  And don’t think it’s basic because the people behind it aren’t very smart.  It’s basic because the people behind it have aimed it at those who don’t have a lot of EFI tuning experience and in particular the owner who likes to play.  Believe me, when you have 256 individual map points on a main fuel map, an offset fuel map and a spark map to play with it’s very easy to just disappear up your own arse in confusion.  The more sophisticated the product the more possibility for screwing it right up.  I know because I’ve been there and done it.  So basic can be good.

There is also another version of the Dobeck unit now being marketed by Moto Creations in the USA and Vee Two which is also software adjustable at dealer level to some extent I’m told.  I have only seen the BMW specific unit carrying the Wunderlich name so far, and these have a couple of extra features to do with the closed loop operation that the other units may not.

There are two Ducati units available under the Techlusion or Dobeck Performance name: the cheaper 1047 which you fit using scotch lock terminal thingys to the appropriate wires and the more expensive 1047ST ‘plug and play’ model which has proper two pin connectors and takes its power from the injectors themselves.  Staintune sell only the 1047ST and the Dobeck Performance websites don’t list the 1047 any more.

Some extra info about the units:

  • The system works by adding fuel in time increments (milliseconds), not in percent.
  • The 3 trim pots on the Ducati units come with a maximum addition of 1.6 milliseconds (ms), although this can be increased on special order.  Setting 1 is zero, setting 11 is +1.6ms (yes, it goes to 11), the other settings increments thereof.
  • The 1047 version adjusts idle mixture as part of the Green adjustment.  At idle the green LED should be on.
  • The more expensive ‘plug and play’ 1047ST unit doesn’t affect idle mixture – the Green adjustment starts at around 1,300 RPM.  At idle all 3 LED should flash.

What I really wanted to know was how or when the ‘yellow’ pot was turned on – was it a preset pulse width or a rate of RPM increase thing or something else altogether.  The only way I was really going to find out was to ride the bike with the Mathesis on the tank so I could read fuel rates and figure it out.  I did this on two bikes – the ST3 and S2R demo bikes I’d been playing with.  The Mathesis display is quite slow in updating – maybe once a second – so it’s hard to be really accurate with pulse widths.

On the ST3 the yellow came on at around 18 to 19 degrees throttle in the RPM range I was riding it at (3,000 to 6,000 RPM).  This corresponded to injector pulse widths of between 5 and 6ms, and was always on for any pulse width over 6ms, but never on for any pulse width under 5ms.  So it seems safe to assume that around 5.5ms is when the yellow will come on.  How this relates to load (throttle angle) depends on the model I guess.

The ST3 idles with around 3.1ms pulse widths and cruise @ 80km/h is around 7.5 degrees throttle and 3.2 – 3.5ms pulse widths.  These numbers are very similar to a 916 fuel map, so I’ve used a 916 Senna eprom fuel map as an example of how the addition of fuel in increments translates into percentages.  The fuel map below is setup as the SFI was for the ST3 – green on 1 (no addition), yellow on 9 and red on 3, with the RPM switch just under 8,000 RPM.  As stated above with this ‘plug and play’ unit the idle is not effected. 

As you can see the red pot is not pulse width based – once you go over the switch RPM you get the red fuel added at all throttle openings.  Meaning the low throttle is very rich.  How this would affect the bike at a track day for example, when you’re in this area of the fuel map coming out of corners I don’t know.  I imagine this is why Dobeck recommended the switch RPM to be set quite high, well above the normal cruising range.  This will need to be considered when you’re setting the switch RPM, especially if you want to set it low based on WOT dyno results.

The owner of the dyno I use also uses the Dobeck units and his comment on a yellow setting of 9 was that there must be something wrong if I needed that much more fuel.  However, given what the fuel map for the ST3 is and what I expected to have to add it seems about right to me.  From all the recommended settings I’ve seen from Dobeck the usual appears to be green on 3, yellow on 3 and red on 4.  This introduces another thing to know – the yellow setting is added to any green setting.  To account for this you also need to remember that 1 is zero and 11 is 10.   So if the green is on 3 it’s 2 increments up.  If the yellow is on 3 it’s also 2 increments up.  But if you wanted to turn the green off (back to 1) you need to turn the yellow up to 5 to keep it the same. 

Tuning the way I do by finding max power settings on a dyno is the reverse to how Dobeck recommend owners do it (this unit is somewhat about owners playing and avoiding people like me).  Mark Dobeck founded Dynojet and the tuning philosophy here uses their same logic as the carb system – you start by getting the pilot setting right (green), then do the needle (yellow), then do the main (red).  Although it’s not quite the same in terms of the correlation between the effects of the red pot and a main jet you get the idea. 

On the S2R the numbers were very similar – the yellow came on in the same 5 to 6 ms range.  As the S2R uses lower flow injectors than the ST3 5.5ms corresponds to a similar throttle opening – around 20 degrees throttle.  On a 620 though, 5.5ms is up around 50 degrees, so I expect the 620 won’t pull the yellow in until much higher throttle openings.

Getting back to the cheaper 1047 unit and the idle interaction.  The SFI pots work by adding fuel in increments.  This is exactly the same as how the idle trimmer in the 1.5M and 5.9M ECU works – it adds or subtracts fuel (from the main map) in increments of pulse width.  So if you set the idle mixture properly you’re then going to override that using the green pot, making the idle richer.  The recommendation I got was to set the idle lean and go from there, but in reality you could just use the idle trimmer in this area and work up from there.

However, as most people don’t have access to a Mathesis, if the baseline setup was right – TPS, etc, you could use the green pot to set the idle mixture (assuming it’s too lean) to effectively give the same result.  And given the idle trimmer and green pot work exactly the same way this will also affect all low throttle cruise.  As most running issues with Ducati are based around leanness at low throttle caused by bad baseline setup I guess this is one way owners can get around the issue.  Even going to the extent of using a gas analyzer to set the idle mixture by the green pot.

As the ‘plug and play’ 1047ST doesn’t affect idle mixture you really need to get the mixture set using the Mathesis for all 1.5m and 5.9m ECU bikes, then adjust the cruise from there.  I did try setting the ST3 lean at idle as I knew a rich idle setting could impact on the high RPM WOT fuelling that would probably be rich anyway with the cam timing mods, but with the trimmer at 0 the idle was around 4% CO.  Knocking it back to -10 gave me around 1.5% CO, but the idle went bad well before that.

This is a bit unusual for the late bikes – the shower injector equipped 749 and 999 often idle quite well at low CO settings, which is amazing given that fuel is dribbling past the throttle blades to get into the engine.  I set the ST3 to -2, giving a CO of around 3.5%.  We usually aim for idle CO of 3.5 to 4.5%, although the Ducati service charts usually say 3 to 6%.  6% just makes them a little richer at lower throttle openings more than anything else.  The S2R was also around 3.5% CO at idle.

I used the S2R to see how much pulse width change corresponded to a 10 point change in idle trimmer setting.  This is for the 5.9m ECU, the 1.5m ECU is 3.6 times less sensitive, meaning a 10 point change on the 5.9m equals 36 points on the 1.5m.

With the trimmer at -6, we had an idle CO of 3.5% and pulse widths of 2.46 to 2.52ms.  With the trimmer at +4 we had an idle CO of 6.5% and pulse widths of 2.66 to 2.72ms, 0.20ms more.  With the trimmer at -1 we had an idle CO of 5% and pulse widths of 2.54 to 2.60ms, 0.08ms more.   So it would appear each point of idle trimmer is worth around 0.02ms, or 8 points is equal to one increment on the SFI for any pot.  And adding one increment to the green pot on the 1047 unit will change the idle CO % by around 2.5.  More on a small engine, less on a big one due to the different idle pulse widths.

As an aside, this is why using the idle trimmer to richen WOT can lead to other issues – to get the same change as the SFI on settings 9 and 11 I’d have needed to add 64 and 80 points to the trimmer.  This would have richened the idle by 50 to 60%, way too much to compensate for by winding out the air bleeds.

Overall using the SFI is defined by how well the requirements of the bike suit the compromise of only 3 zones of richer adjustment.  I use the FIM zone system on the older “ECU with eprom” bikes and having 3 zones for the WOT RPM range alone can be frustrating sometimes.  That system uses 7 zones of adjustment plus an overall adjustment, all in plus/minus %, and for most jobs we do – inlet, exhaust and cam timing mods – it works very well when based on the Ultimap eprom series with their quality mapping.  But with the SFI if you have a situation where you go lean then rich then lean at WOT (as the S2R did) the SFI won’t give you what you need.  I understand why they went with the 3 zone thing in a marketing sense, but it really is rather limiting.  Working in millisecond increments is also limiting compared to working in %.

Overall, I had mixed results with the SFI.  The ST3 responded quite well to it, the S2R showed its limitations.  This is very much the nature of even basic mods – the result is rarely consistant, and the 800 engine’s mapping is quite effected by inlet and exhaust changes, whereas the very similar 620 and 1000 are much less so. Even the ST3 shows fairly minor air/fuel changes with the usual mods.

Changing the engine characteristics markedly will exceed the limits of the SFI fairly quickly I expect.  Large increases in capacity could also create some issues - in that situation % changes are much more appropriate.

If I get to play with one of the later units I’ll update this report.

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