General Technologies TA500 SmarTach+COP : Multisystem Engine Analyser - Manual (Page 7)

4. APPLICATION INFORMATION
4.1 Taking measurements
1- Select the ignition system to measure following the instructions in in ‘3.4 Measurement
Procedures’.
2- Observe the spark burn time and spark KVolt reading of the display. Some variations
of the readings are normal and reflects actual changes in the spark voltage and burn
time in the ignition system.
3- Record or memorize the maximum, minimum and average reading. Repeat the
test for each of the spark plug wires or ignition modules of the engine and note any
readings that are significantly higher or lower than the average.
4- Ignition problems may sometimes appear at higher engine RPM, but not at low
or idle speed. We recommend that measurements be made at idle speed and
normal engine operating temperature, and then at increasing RPM, and up to
equivalent of highway speeds, typically about 2000 to 2500 RPM. Do not exceed maximum
permissible (“red-line”) engine speeds. Make all measurements at about the same
engine speeds, using the TA500 tachometer function to check the RPM.
4.2 Diagnostic using spark burn time and spark KVolt readings
Small variations in spark burn time and spark KVolt readings from cylinder to cylinder are
normal, and do not indicate any problem.
For diagnostic purposes, the attention should be focused on SIGNIFICANT DIFFERENCES
in readings, most likely caused by problems in the engine or the ignition system itself.
Important:
• The RPM and spark burn time displayed by the TA500 are absolute measurements.
• Spark KVolt is a relative measurement and should be used only to compare between
ignition modules or spark plug wires in the same engine.
• In COP mode, always perform a calibration of the spark KVolt in one of the ignition
modules as described in ‘3.4.2 Measuring Coil on Plug and Coil near Plug ignition
systems’ before proceeding to measure and compare results between cylinders.
• When measuring on spark plug wires (SPW mode) the placement of the capacitive
pick-up along the spark plug wire will also cause some variation, due to the internal
resistance (or impedance) of the spark plug wire. For example, if the capacitive
pick-up is placed on the spark wire near the distributor or the DIS coil, voltage reading
will be higher than if placed near the spark plug.
4.3 Common causes of long burn time readings
• Shorted, dirty or too small spark plug gap.
• Dirty or damaged spark plug insulator or boot allowing spark “tracking” across
insulator.
• Rich mixture. Most likely due to leaking fuel injector, or faulty oxygen sensor.
• Low cylinder compression pressure. Could be caused by leaking valves, worn piston
rings, blown cylinder head gasket, etc.
3.5.2 Capture function (For COP and SPW modes)
The capture function is used to measure and hold maximum spark KVolt and spark burn time
readings. This function is most useful when performing a no-start test or when measuring
ignition modules in places in which it is difficult to position the capacitive pick-up over the
module and read the display at the same time.
To use the capture mode:
1- Follow the directions in ‘3.4 Measurement Procedures’, to setup the TA500.
2- Press and hold the ‘Secondary Function / Capture’ button (for approximately 3
seconds) until a flashing “CAP” appears in the secondary display A.
3- To exit the capture mode, press the ‘Secondary Function / Capture’ button
momentarily again.
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Notes:
• The capture function holds the maximum spark KVolt and spark burn time displayed
(measured) values.
• The values held while in capture mode can be reset by pressing the ‘Power ON/OFF
/ Reset’ button momentarily.
• When in capture mode, only the ‘Power ON/OFF / Reset’ and ‘Secondary Function /
Capture’ buttons will remain operative, in order to prevent accidental changes in the
setup of the TA500.
• Upon exiting the capture mode, the held values are reset.
3.5.3 Auto power off
To help prolong battery life, the TA500 will automatically turn off after a period of
approximately 3 minutes of inactivity.
A period of inactivity means:
• No buttons are pressed
• No measurements are taken
Burn Time
Cycles
mS
Peak
Fig. 8 - Typical display in capture mode
Flashing letters