There's a distinction between gear change and lock-up when
there's an abrupt drop in rpm.
For the latter, I know some buses tend to lock-up too early and
this means it has to lock-up again. This is due to a faulty
setting, and fits the description you have described, which is, it
fails half the time. They did not move on to the second gear but
tried to rev again at first gear once more.
For the former, the pitch of the engine will be entirely different
(though it may sound minimal to most people) when it's at second
gear, and the rpm drop is actually not as abrupt as a faulty
lock-up.
Most ZF gearboxes will, when it had cleared the first gear then
dropped back to second gear and wishes to accelerate, lock-up at
the second gear. This lock-up will sound like it is dragging and
will take longer. The ones which will occasionally jump back to
first gear and rev up again are usually LO3x's and 6HP's on B9TL
and KUB. A small number of Striders do that too.
Maybe you can give me the regos of the VO3x's next time then I'll
visit the buses. (:
It sounds more of the configuration of LO3x
It has this uniqueness when it was in HGDEP
SBS9600K is another bus that has this uniqueness but sadly few
months back they tune back it to normal configuration.
Asked the BC who drive the bus, he mentioned that it does not have
much strength and the temperature of water can hit 100 degrees
easily as he need to keep on step on the pedal.
