Firstly thank you for taking the time to try to and offer some advice. i am a recent owner of a low milage 848SF, but sadly has recently developed a strange fault. when ridden normally there is no issues, however as soon as you start to ride it urmmmm enthusiastically , the engine management light comes on and shows a fault via the dash as step 21.2. once you come to a stand still 99% of the time disappears again. i understand this is relating to the stepper motor which i have removed cleaned resembled and tested and you can hear it operating once the ignition has turned off. performance wise i would say the bike is lacking in power i would describe it as flat (i also own a 848 as comparison). i have checked for the obvious things such as vacuum leaks ect any help or pointers would be great
The exhaust vavle was seized up however i have now got it constantly open and have tricked the servo with a spring and and cable, I was under the impression that the exhaust vavle stays open after a certan throttle position and it was simply for noise reduction.
Checked both lambdas both plugged in,a and no misfire. Strange though why it brings a fault up for the stepper motor. Any ideas as to why it would open once its up to temparature??
not really no. any possibly of an air leak? does it have a scot oiler? vacuum hoses good?. lamda probes can send faulty signals without showing errors. only a postcat lamda can affect the running. sometimes you can disconnect them and then see how it runs to diagnose. low fuel pressure from a partially blocked fuel filter. tps sensor track issues.
by stepper motor i wonder if it means idle speed control vale. does it have one? and could it be its gone out with its operating range trying to maintain a tick over because of an underlying running fault?
