I have a 2013 V7 stone with 25,000 kms on it. It is my daily rider for commuting. Over the years I have noticed that it doesn't always feel the same each day when I ride it. Some days if runs great others it runs poorly. Often I found that after just starting it if I got on and rode right away it would stall. I even recall when I originally picked it up from the dealer and he had it idling in the parking lot that it seemed to hunt for the right idle rpm and would cycle up and down in rpm, just sitting there - day 1.
Since then I have learned a lot about whats going on with this bike and it is all about the fuel injection system. I would like to share a brief overview just in case anyone wonders.
The fuel injector system has a variety of inputs such as: Throttle position; air temperature; engine temperature and atmospheric pressure, rpm, crank position, speed. The output of the fuel injector computer (ECU) is pulses to each of the two injectors. The pulses turns on each of the two injectors at the right time in the piston position cycle and for a certain amount of time, ie pulse width, delivering a prescribed amount of fuel for that throttle postion, given all the other inputs. The supply to the injectors is fuel at about 80psi (from the fuel pump in the tank). Pulse length of injector 'on' time directly relates to the amount of fuel delivered to the cylinder.
Soooo. .. There is a 'map' in the ECU memory that translates the inputs (throttle position et al) to outputs ( pulse duration) given all the other inputs (temperature, rpm etc). This map comes in the bike from the factory and is designed to give performance but also to meet emissions requirements. From what I have learned, the settings tend to be a bit 'lean', that is to say a lower fuel to air ratio, in order to meet the emissions requirements. The result of being a bit lean is that it idles a bit roughly and a bit hot.
There are after-market fuel maps that you can buy and download to your bike, they tend to be non emissions compliant from what I understand but deliver better performance. The tool to apply them to your bike is free and runs in windows and can be obtained at guzzi diag here;
http://www.von-der-salierburg.de/download/GuzziDiag/ . I used this tool and applied the latest factory map to my bike, after experimenting with a purchased aftermarket map first. The factory update map that I applied was 352BV738 which was released long after my bike left the factory. It was simple to apply using that tool and an ebay ODB2 USB adapter that is needed for the interface.
After all of that I learned one other key thing. The ECU has two modes for referencing the fuel map: 'open loop' and 'closed loop'. In open loop the ECU uses the inputs (throttle, temperature, rpm, etc ) and the map to set the injector pulses. In closed loop, the ECU also measures Oxygen content in the exhaust (via the o2 sensors in the tailpipes) to measure unburned fuel and hence what the actual lean / rich mixture is. By measuring this, the ECU adjusts its pulse output, versus the map, to fix the too rich / too lean results as measured from the exhaust. This helps to meet emissions and to be more fuel efficient. The ECU, however, only uses closed loop when the rpm is constant for a while such as after a few seconds of idling or at constant speed on the road. As soon as you twist the throttle and ask for power it reverts to open loop as the closed loop sampling is too slow to accommodate a sudden need for power.
I have relaized that this is why my bike was 'hunting' at idle when i picked it up; the feedback loop was too rich / too lean/ too rich etc, and the ECU was adjusting on the fly but the closed loop is slow, so the idle would go up and down as it adjusted.
Also this explained my stall when idle and cold. It would be in closed loop after idling for a few seconds, then when I twisted the throttle it would go to open loop but clearly the map was too lean at that point in the open loep and it would stall. You can see in the guzzi diag tool when you are in open versus closed loop. Similarly I found that on the road if I twisted the throttle to accelerate there was a delay that made me think I had a sticky throttle, but this was really just the time to go from closed loop to open loop and apply power.
I think I also have one o2 sensor that is flakey and sometimes gives the ECU a bad reading which makes this whole closed loop thing quite unreliable.
So I unplugged both my o2 sensors and the ECU then reverts to open loop all the time. The result of this with the new fuel map is great. No hunting at idle, no stalling when cold, no hesitation when accelerating. I assume that I would no longer meet emissions and that I am slightly less fuel efficient, but i realized that the bike is really only in closed loop very little of the time anyway and it is the
transition from closed to open to closed that caused me trouble. So for me, the new map and disconnected O2 sensors such that I am open loop all the time, gives me a good performing bike.
