Download TIMING LIGHT - Draper Tools

ENGINE TIMING
Proper ignition timing is critical in order to achieve peak engine performance and to ensure
maximum fuel economy. An ignition system timing check is critical during any tune-up procedure.
DEFINITIONS OF TERMS
DIS: Distributorless Ignition System; vehicles are equipped with multiple coils and a “control
module” for controlling spark distribution. Such systems may also be referred to as EDIS, IDI, C3I
or EI.
ECM: Electronic Control Modules, the vehicle’s on-board computer system. May also be referred
to as ECU, Brain or Module.
Ignition Timing: Checking when the No. 1 cylinder spark plug “fires” in relationship to a timing
mark or other reference point.
Late Model: Refers to vehicles manufactured during the current model year to vehicles
manufactured approximately four years earlier. For example: 1992 to 1997.
Tune Up: With reference to today’s “self-tuning” vehicles, the meaning of the term “tune-up”, has
changed significantly. A tune-up consists essentially of checking engine operation with Original
Equipment Manufacturer’s (OEM) specifications. Adjustments are made and parts are replaced
ONLY if engine performance is not within OEM specifications
ABOUT THE TIMING LIGHT
This Timing Light is designed for all 12 volt negative ground vehicles. Some models may also be
used on vehicles equipped with DIS (distributorless ignition systems).
1. OPERATING CONTROLS AND INDICATORS - GENERAL
(a) Xenon Bulb – Used to illuminate timing marks for checking timing.
(b) Swivelling Head – Contains the xenon bulb. Rotates over approximately 90° to allow for
easy illumination of timing marks in hard to reach locations.
(c) Control Panel – Contains the controls and indicators necessary to operate the timing light.
Specific controls and indicators vary between models. Refer to the appropriate paragraph
for a description of control panel controls and indicators:
(d) Inductive Pickup Lead – Detachable leads assembly to connect timing light to ignition
system:
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