PC being Power Commander of course.
I'd already picked up a used Power Commander lll USB a few years back, I saw it come up on a Ducati forum and thought "Ooooh, I'll be needing one of them soon..." "soon" apparently being +5 years later! Oh well, time to finally get it installed so I dragged it out, blew the dust off and sized it up. It was quite surreal: the 851's electronic fuel injection was absolute cutting edge at the time, far in advance of Power Commanders and the like which didn't appear until nearly 10 years later in 1997. Yet here I was, trying to add modern tunability to what was now an electronic artifact. As Dr Seuss asked: "How did it get so late so soon?"
As no PClll's were made specifically for the 851/888 I had no option but to use something intended for a later bike, this being a Ducati 998 unit:
All good, eh? Er, not quite.....when I'd received the padded mail bag all I'd done was crack it open and confirm, yup, there's a PClll with a bunch of cables, and stashed it away for a later date. If I'd had a better look I would have noticed that I was missing one section of the harness:
The PClll is called a "piggy back" device but it's probably more accurate to call it an interception device. It basically intercepts the pulsed signals to the injectors and applies a pre-programmed correction factor before sending the corrected pulses (shorter or longer for more or less fuel) on to the injectors. The injection pulses correspond to rpm and the red terminal above picks up throttle position, so the correction factor is mapped against all given rpm and throttle positions to give optimum fuelling.
But without that section of harness all I had was signals going into the PClll but no way of firing the corrected signals off to the injectors. I put the word out on forums if anyone had a busted/damaged PClll I could use for parts, even asked the Australian distributor if I could buy a harness section, but no joy. Eventually I had no option but to find another cheap PClll online and pinch the lead off that, but it was a frustrating lil' hold up that I should have picked up earlier.
Now, to install the PClll you just unplug the OEM leads at the injectors and connect them to those lower un-circled connectors in the photo above, then connect the circled plugs onto the injectors. It's all colour coded so even I'd struggle to cock it up. One more termination connects to the Throttle Position Sensor, and you need a Ground connection, that's it...pretty simple eh?
So why does the ol' girl look like a puppy's play toy, with its insides on the outside?
For ease of access I was mounting the PClll on the battery holder panel, just above the battery:
It looks worse than it is, just a bit frustrating having to remove that mongrel airbox to install the harness with the rest of the wiring loom.
Bewdy, job done, time to fire it up....er, fire it up...oh c'mon...wtf?! The PClll is supposed to cycle through the throttle position bar graph on power up, but there's not even a flicker. Awwwww man it's pretty simple, hard to screw it up, but then I've under-estimated my stupidity before so I check everything over....
....nope it all looks fine and I'm at a complete loss, so I break for lunch (and an inspirational beer). Nothing. More inspiration (beer) is obviously required...still nothing.
I've actually got her booked in for a dyno tune in 2 days time so I really need to sort this.
In desperation and apologising profusely I called Russel at Dynotime, not only is he a suspension guru having done the business with my forks, but as per the business name this sort of stuff is his bread and butter.
And he was a bloody gem. He could have easily brushed me off, but instead put his thinking cap on and worked through it with me over the phone. We were still at a bit of a loss until he started musing about working with Justin up at Pro Twin and recalled him saying something about a polarity issue. And that was all I needed to hear.
The ECU does not switch 12v volts to the injectors when they are fired, the injectors actually have a permanent 12v supply and it is the ECU's job to switch that 12v (after the injector) to ground, which complete's the circuit and fires the injector. So when you unplug the supply to the injector and connect it to the PClll you are also supplying the power for the PClll. My problem? The Magneti Marelli P8 ECU was used in some models right up to the 996SPS, predecessor to the 998, so I'd just assumed there would be some standardisation....but somewhere in the 20 odd years between the 851 and 998 Ducati had reversed the orientation of the wires in that incoming injector plug. And BOOM we were away....
...on one cylinder! You have got to be fkkn kidding me?!
This time my fault finding was a lot more successful, but all the same I really didn't need to be bolloxed by stuff like this at one of the OEM injector plugs:
If I could have found its neck I would have surely done a Homer:
With that out of the way I also needed to sort some sort of air filtration prior to the tuning session, as the filter could realistically have a fair impact on air flow. I'd been ruminating on this for a while, just rolling it around in my head as I plugged away. The non-OEM Corsa-style airbox makes things a tad tricky as the airbox isn't even remotely sealed, and the race bikes never ran any sort of filter, so you are left with trying to fit something over the throttle bodies/intake trumpets themselves.
I was pretty impressed with the Pipercross filters fitted to the 749R/999RS so I had a look through their "cattle-dog". For a minute there I thought I was reading their smoko menu as I found myself looking at what looked like a loaf of bread...made of foam. It was intended for a 916 but would suit my application perfectly:
They call it a "sock" but it really is a "loaf", and If you imagine that loaf with a couple of pockets eaten out for the intake trumpets you have just pictured exactly what this is. I thought it might also help create pockets of still air in what I imagined to be quite a turbulent environment with air rushing out of the unsealed airbox.
A soldering iron through the foam formed a nice snug tunnel for the cross member. Job done, I think we're ready for the dyno...
