Westerbeke 6.5 MCG Service Manual page 66

ON·BOARD DIAGNOSTICS 1 PC INTERFACE SOFTWARE
Start off by collecting date from the time that the engine is
started.
If
you have a genset that has the idle mode, start the
PC interface communicating and data logging before you
start the engine.
If
you have an engine that does not have an
idle mode, start the PC Interface as soon as possible after the
engine is running. Let the engine warm up for about 10 to 15
minutes before trying to apply an AC load. Monitor and
record AC volts and amps if possible.
After the engine is warmed up, start applying an AC load by
turning on various devices. Let the unit run at each load
change for a couple of minutes so that the unit is stable.
Monitor and record AC volts and amps if possible at each
load site. Continue to as AC load until the unit is at or near
full power rating. Power is determined by multiplytng the
AC voltage times the AC amperage. This will determine if
the unit is overloaded or not.
After loading up the genset, begin to reduce the
1-c
load. Let
the unit run at each load site for a couple of minli.tes to
stabilize. Continue to reduce the AC load and monitor
voltage and amperage until there is no AC load on genset.
This will give a technician a baseline of what is going on
when the engine is running under a controlled load condition.
Finally, after running the controlled baseline test, this might
sound strange, but sometimes the customer might know a
particular scenario that will cause a problem for the unir.
Sometimes we hear customers say that the unit runs fine for
awhile and when my air conditioner shuts off something
happens.
Try
repeating the scenario that the customer men-
tions. Always start by recording date from the start up for a
least a couple of minutes with no load on the generator to
get a starting point. Then continue to record data until the
problem shows up.
If you have a unit with no idle mode, and the unit shut down
under some kind of fault, the date log will automatically stop
and save the file. If you have a unit with an idle mode, and
the unit was to shut down under some kind of fault, you will
have to manually stop the data log to save it. Or in the case of
shutting of the DC circuit breaker, this will also cause the
data file to stop and save itself.
WHAT TO DO WITH THE DATA
All of the data that is being recorded is also being displayed
on the PC Interface in the various boxes. The following
information applies whether you are looking at the data file
after it has been recorded or watching it live in the PC
Interface. The data file can be opened in most spreadsheet
software such as Microsoft Excel.
Some of the data that is being collected is pretty much self
explanatory and simple to follow. For example, I think that
engine temp, air temp, oil pressure, and battery volts would
be easy to figure out. Some of the other items may be less
familiar.
64
Sp,eed
Simple enough, this is the speed that the engine is running.
the genset is set up to operate at 60 Hz, then the engine needs
to run at 1800 rpm (belt driven units may be different). If the
unit is set up for 50 Hz operation then the engine speed will
be 1500rpm.
When a genset is
gov~rning
properly, you should see read-
ings slightly above and below the desired speed. Even a well
tuned engine will vary a little. The point is you should see
readings above and below the desired speed. If you see speed
readings remain more than 20 rom above or below the
desired speed for a prolonged period of time, there could be a
problem, especially if this is noticed with no AC load
applied.
If the speed is too high with no AC load applied, check the
data box labeled Stepper Pos. (steps). The throttle is con-
trolled by a stepper motor. Usually the step count for the
engine running with no AC load is typically in the 20-30
steps range. A couple of steps above or below this range
does not indicate a problem. However, if the step count is in
the single digit numbers or even showing a zero, the problem
maybe that the thrrottle body assembly may be out of
calibration or not functioning properly. The stepper motor
can only go to a positioin that it thinks is zero. If the
calibration is off, the stepper cannot move the throttle closed
enough to slow the engine down. An engine that has this
problem will run at the proper speed once some AC load has
been added. However, when that load is dropped, the speed
will be too high, and in some cases may cause the engine to
over-speed and shut down.
If the engine speed is too low with no AC load applied, there
is probably a totally different problem. Again, look at the
Stepper Position. Is the speed low but steps are high? This
would mean that the throttle is being opened to compensate
for loss of speed but the speed is not coming up. Check
to
make sure that the
fuel
level is full in the fuel system and that
the fuel is good and the filters are clear. Bleed the fuel system
to remove any air. Check to make sure that the air intake
screens are clean. Check to make sure that the spark plugs
have not fouled.
If the engine speed is okay when running with no AC load,
but once underway with some AC load being aplied the
speed drops and stays below the desired speed, first check the
AC power by multiplying the total AC amperage times the
AC volts to get the kilowatts. If this number is higher than
what the unit is rated for, then it is overloaded., Shut off
some of the devices until the speed returns to normal and
check the power again.
If
there is only a small AC load
applied and the speed cannot maintain, follow the same
suggestions from the previous paragraph.