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This is only a preview of the February 1996 issue of Silicon Chip. You can view 26 of the 96 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Articles in this series:
Items relevant to "Computer Bits":
Articles in this series:
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Engine Analysis On The Run . . .
Fluke 98
Automotive
ScopeMeter
Every auto shop these days has
an extensive array of electronic
engine analysis equipment.
Now there's one that fits in the
palm of your hand for "real
life" measurements and even
personal computer analysis.
By RICK WALTERS
T
HE FLUKE 98 AUTOMOTIVE
ScopeMeter provides a compact
measuring system with a large
liquid crystal display which will allow
auto mechanics to carry out a wide
range of diagnostic measurements, both
on the bench and on the road.
When it was released, the Fluke
ScopeMeter was a clever concept
which was immediately accepted by
the electronics industry. Now Fluke has
produced a new version aimed at the
car service industry, the Automotive
ScopeMeter.
The measurements available include
voltage, resistance, dwell angle, oxygen
sensor, general sensors, RPM, primary and secondary ignition, relative
compression and EFI duty cycle. In
addition, by using the optional diesel
probe set, diesel injector pressure pulse
4 Silicon Chip
and diesel advance measurements
can be made.
Engines catered for include three,
four, five, six and eight cylinders,
two and four cycles, diesel or petrol
and 6V, 12V & 24V batteries. It also
can measure conventional Kettering
ignition systems with a distributor,
vehicles such as the Holden V6 with
distributorless ignition and vehicles
with a coil for each spark plug.
Probably one of the most useful
features of the ScopeMeter, especially
for new users, is the help system. The
trouble with most modern electronic
equipment, from the humble video
to even the mobile phone, is that the
number of functions packed into the
unit is so great that the manual is
needed each time you need to carry
out more than the basic operations.
The Fluke has a big yellow MENU
button which, when pressed, brings up
the menu screen. The selected function is shown in reverse video and the
up and down arrow buttons are used
to scroll through the menus. Above the
F5 button the SELECT legend is shown
(1-7). Once the choice is made, full
instructions appear, showing which
leads to use and which ScopeMeter
input to connect (1-8). This “connection help” function can be turned off
once the user is completely familiar
with the unit.
As well as the menu help, there
is a key labelled “i” which, when
pressed, displays information about
the highlighted menu choice, while
you are in the menu program (1-12) or
information about the function keys,
when a test is running (1-14).
Fig.1: this graph shows the relative
compression of each of the eight cylinders
in a Holden V8, recorded at a cranking
speed of 133RPM. The "best" cylinder (in
this case cylinder 6) is rated at 100%, with
all others relative. The variations between
cylinders in this 85,000km-old motor are
clearly evident.
The ScopeMeter is normally powered from its internal nicad battery,
with a mains plugpack supplied to
recharge or trickle charge it. In emergencies, four standard “C” cells can be
used but these cannot be recharged.
The use of batteries allows “on-road”
testing to be readily carried out.
One very useful accessory supplied
as standard is the automotive demonstration board. This small PC board
simulates five functions, allowing you
to become familiar with the operation
and functions of the ScopeMeter at
your leisure instead of under the
bonnet of a car.
The board outputs are labelled
injection, secondary ignition, sweep,
general sensors and oxygen sensor.
Chapter two of the comprehensive
manual includes a tutorial using the
demonstration board to carry out eight
simulated tests.
It starts by taking you through the
process of measuring the voltage of
the 9V battery supplied to power the
PC board. The next tests are resistance
measurement and two plots of the voltage across the SWEEP potentiometer
on the PC board for clockwise and
anticlockwise rotation.
This is followed by a measurement
of the oxygen sensor signal, using the
RPM potentiometer to vary the viewed
waveform. Next are general sensor
Fig.2: data from the Fluke 98 (screen shot at left) has been transferred to
the personal computer database for this particular vehicle. A profile of
vehicle performance over time is a very handy aid in vehicle diagnostics.
and RPM measurements, again using
the RPM potentiometer to vary the
displays. The last tests measure a simulated secondary ignition coil voltage
and an injector waveform.
By the time you have worked
through these examples you will be
quite conversant with the selection of
the menu screens and the interpretation of the readouts.
The tutorial continues with a description of the methods used to plot
one parameter over a period, how to
plot a trend which will compute the
maximum, minimum and average
values over the period and how to use
the “flight record”.
This flight record is a very useful
function, allowing you to store up to
1280 divisions in a cyclic memory,
the length in time being equal to 1280
times the timebase setting in seconds.
This means, for example, that if the
timebase speed is 10ms per division,
you could store 12.8 seconds of information. So what use is it?
Let’s say that you have a vehicle
with an engine misfire under load and
you don’t have a dynamometer. To
diagnose the problem, you turn on the
Fluke, select ignition, secondary, OK,
record and flight record, connecting
the leads as instructed. You then take
the car for a run and when the fault
occurs, you press the clear memory
button. This starts saving the measurements into memory. Once you have
felt the misfire, you press any button
to store the information. When you get
back to the workshop you can analyse
the stored information and decide on
the steps necessary.
Among the options is SW98W,
FlukeView 98 for Windows Software.
This allows the transfer of any stored
waveforms to an IBM or compatible
PC with, at minimum, an 80386
processor and Windows 3.1. Once in
the computer, you are able to read,
document, save and print any results
from the Fluke.
The software allows you to keep a
record of the relevant parameters for
particular cars or perhaps even particular clients. By comparing current
data with previously stored information, the present state of tune can be
readily established.
These records are kept in a database
which can be set up in a way which
best suits your application. For example, you can group the information as
Manufacturer, Model, Engine Capacity, Test Category, Test 1, Test 2, or
Manufacturer, Engine Capacity, Test
Category, Test 1, etc.
A neat feature of the database is that
when you are selecting a previously
saved screen, as you change the model
or capacity, the thumbnail sketch of
February 1996 5
Fig.3: this graph shows the firing voltages for each of
the cylinders of the Holden V8 engine. Note again the
variations from cylinder to cylinder.
the graph changes immediately, to reflect your choice. This helps greatly in
locating a particular record, especially
if you know what the waveform you
are searching for looks like.
Once you have become familiar with
the operation of the ScopeMeter, the
94 pages of chapter five of the manual, headed automotive applications,
describe the procedures for testing all
vehicle sensors, along with expected
readings and waveforms.
Fig.4: an "ideal" injection pulse for a specific engine as
shown by the Fluke 98 software database. This allows
mechanics to instantly compare results achieved during
tests with manufacturer's specifications.
Sections follow on air/fuel, ignition,
electrical system and finally diesel
RPM and advance measurements.
This review has only covered some
of the wide range of measurements of
which the unit is capable. Features
such as single shot function, dual trace
operation, etc are all fully covered in
the comprehensive user manual.
The current cost of the Fluke 98
Automotive ScopeMeter is $3990.
An automotive temperature probe is
Protect your valuable issues
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$330. The FlukeView 98 for Windows
software is $435 which includes the
optical connecting cable. The diesel
probe set is $440. All the above prices
exclude sales tax which must be added
to the figures quoted.
The review sample came from
Philips Test & Measurement. For
further information, contact the distributors, Obiat Pty Ltd, 129 Queen St,
Beaconsfield, NSW 2014. Phone (02)
698 4111. Fax (02) 699 9170.
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