While many of us have spare 'bandwidth' during our interminable incarceration, I thought I'd ask for some help with this. My Moto Morini developed a major issue last year that has, to date, proved insoluble. Sharing, as it does, all ignition, fuel supply, injectors, ECU systems with Ducati, I thought I'd ask the forum and see whether what has so far defeated the current Morini importers, the historical, long standing previous importers and two separate respected, now independent, Ducati factory trained technicians, can be answered here... The symptoms are; it runs clean as a whistle until revs drop to 1400 RPM and there, the engine cuts out. Dead. Have to restart, no matter road speed, or what gear its in. I realise the tickover could simply be wound up to 1450 RPM, but that isn't the answer. My limited knowledge of fuel injection tells me that below 1400 RPM, the stepper motor should be controlling the tickover once the enriched cycle finishes. This seems to be what is not happening. So far, this is what has been done: New plugs New coil sticks Fuel tank removed, drained and dried out to be certain there was no pool of water Fuel filter replaced Internal fuel hoses replaced to ensure there was no loss of pressure from a tiny split The whole fuel tank was also swapped over at NLM, again to ensure it could be entirely eliminated along with all its components The dash was also swapped to eliminate any issue with temperature readings that are stored there My Morini has a BDS map, that was also removed and replaced with a standard factory one and when it made no difference, they were swapped back. The ECU was swapped for a factory fresh one, again no difference The stepper motor was also substituted for a brand new one sent by Morini to try and solve the problem for me (on a 10 year old bike!!) - no change.. A leak down test Brand new TPS The loom between the ECU and stepper motor was also forensically checked and found to be fully OK Nothing done so far has made one iota of difference! I have come to the conclusion it must be a faulty sensor sending corrupt info to the ECU that works perfectly, but then sends gibberish instructions to the stepper motor, that is also working perfectly well, but not doing what it should, based on those instructions. Does that make sense? If so, does anyone have any suggestion as to the likely culprit sensor? The bike worked perfectly when it was put away, but a few months later, when called back into action, it had become this recalcitrant beast.. Any ideas? Thanks
The only sensor I can think of that could affect the stepper motor is the crank sensor although I've never heard of that happening. Usually they fail completely or at high revs although I came across one that allowed the bike to start but run really roughly across the range as if the timing was out, which it probably was.
Sounds more like charging circuit to me, right where the alternator kicks in at 1400 rpm onwards. Voltage is my guess as it controls everything electrical, Have you checked amps and volts with a scope or decent meter>
Have you cleaned the stepper motor? Many years ago I ran an injected yank motor and it suffered from a sooted up stepper on a regular basis which caused tick over problems. The valve sits quite close to the seat and when it gets covered in crud can disrupt the airflow at tick over to the point where the engine won't run. Don't know if this would apply to your Morini but sounds like you're running out of options
The bike runs beautifully throughout the rev range above 1400.. however, thank you Derek, I'll look into replacing the crank sensor. No, Peter, I haven't checked, largely because I had no suspicion relating to charging as after a trip down to Madrid on it last year, taking in the hundreds of hairpins during 2 days riding in the Picos, the 2,000 or so, engine re-starts in Madrid traffic and Picos nadgery, convinced me that the strongest components on the bike were the starter motor and battery! Again, thank you, I will get it tested, as you suggest. Thank you Hugh, this is one I can discount though, having swapped the stepper for one that @final_edition kindly donated to the cause, and also with the one the factory sent. Thank you for your suggestion
