17 18
valve open.
When the pulse ends, the injector nozzle is closed.
This open to close time is the Pulse Width and is measured in
milliseconds (ms).
The most common automotive application for measuring pulse width is
on fuel injectors.
You can also measure the pulse width of the fuel mixture control
solenoid and the idle air control motor.
This exercise shows how to measure Pulse Width on Port Fuel
injectors.
(continued on next page)
To measure pulse width (mS):
Select the
“mS-Pulse”
function
with the function dial.
Press the
±
TRIG button for 2
seconds until the negative (-)
trigger slope is displayed on the
upper left side of the display.
NOTE : The applied time for most
fuel injectors is displayed
on the negative (-) slope.
Insert:
Black lead in
COM
jack.
Red lead in
V-
Ω
-RPM
jack.
Connect:
Jumper wires between the fuel
injector and the harness connector.
Connect black test probe to a good
ground at the fuel injector or the
negative (-) vehicle battery post.
Connect red test probe to the fuel
injector solenoid driver input on the
jumper cable.
Start the engine. A pulse width in
milliseconds should be read.
Note: Initially, the unit will read “OL”,
then readings will descend and
stabilize to the actual pulse width. If
“OL” remains, re-check your
connections.
Meter Functions-RPM/
×
10RPM
Select the
RPM
range with the
function dial.
OR
Select the
×
10RPM
range with the
function dial (1,000 to 12,000 RPM).
Multiply the displayed reading by
ten to get actual RPM.
Press STROKE / DIS
button to select through
RPM for 4-stroke, RPM
for 2-stroke and DIS ignitions.
Connect the inductive pickup
by connecting leads to the
meter.
Black lead in
COM
terminal.
Red lead in
V-
Ω
-RPM
terminal.
Clamp the inductive pickup to a
spark plug wire. If no reading is
received, unhook the clamp, turn it
over and connect again.
4
2
4
2
¦ ¸
Auto Power Off
4
2
Black-
Red +
Mixture
Control
Shown
GOOD
GROUND
JUMPER LEAS
FROM PORT
FULL INJECTOR
¦ ¸
Auto Power Off
4
2
