I've had an Arrow system on my 2015 DVT since day one and the bike has always ran fine. This summer I've kept it overseas and about 3 months ago it started to misfuel below 4k in any gear resulting in a really jerky throttle. It also popped loudly on the overrun and is using much more fuel under 4k (mate's riding behind me could smell the unburnt fuel). Over 4 k in any gear it's absolutely fine. At first I thought the fault was the exup valve 'cheat' spring arrangement that came with the Arrow so about a month ago I fitted a vizi-tec DUC.EE servo eliminator. This made no difference and in the last month the problem has got much worse. I'm having to slip the clutch all the time below 4k to stop the bike kangarooing down the road. The bike is overdue it's 12k service and bizzarely fluctuates between showing no engine light through solid engine light and sometimes flashing light. I've got the red 'date service' showing on the dash and also a red square showing 'BB' next to that. I'll be riding the bike home in October and getting the big service done. As 99% of the journey will be motorway and thus over 4k revs it'll be OK I guess but has anyone got any idea what could be going on?
Sounds like a faulty lambda sensor. The ecu runs closed loop fueling below 4K rpm and at low throttle input, meaning the ecu adjust fuel depending on lambda sensor input. At wide open throttle the ecu adjusts fueling from a fixed fuel table and it should run ok in all rpms even with a faulty lambda.
I did. I rode the bike home from Italy (as 99% of the journey was over 4k revs it was fine) and took it to On Yer bike at Aylesbury. They immediately said the 'misfuelling' was actually due to the bike dropping down to one cylinder when running below 4k. However it took them a couple of days to diagnose the fault. It was a split in a vacuum hose that was sealing itself up at 4k!!!! The hose cost £3.79 IIRC. I had quite a bit of other work done so they didn't charge me for the time spent trying to trace the fault. She's running sweet as now.
