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Engine Tune-Up

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					Engine Tune-Up
   By Jonathan Rollins
   Tune – Up Procedures are done as part of a
    routine maintenance rather than to correct a
    drivability problem.
Wear safety glasses!
Spark plug replacement
   Most new engines do not require spark
    plug replacement for up to (100,000 miles)
Normal service and replacement items
in a minor tune-up are…
   Perform a visual inspection for obvious problems
   Check for trouble codes on computer controlled vehicles
   Replace spark plugs
   Service the ignition system, including checking secondary components
   Replacing the air and fuel filter
   Changing oil and lubricating the chassis
   Testing and servicing emission control system, and resetting the reminder
    circuit
   Adjusting the fuel system if applicable
   Cleaning the throttle body and idle air bypass on fuel injected engines
   Road testing before and after tune-up to check engine performance
Service and replacement items in a
major tune-up are…
   Perform a scope analysis of engine system
   Testing and replacing spark plug wires
   Testing and replacing fuel pump
   Replacing drive belts
   Replacing brake, transmission, and other fluids
   Replacing or rebuilding the throttle body
   Rebuilding or replacing the distributer
   Adjusting the valve train (some engines)
   Replacing weak sensors: oxygen sensor, cam position sensor, crank shaft
    position sensor, ect
Six of the diagnostic tools
used during a tune-up are…
 scantool, an exhaust gas analyzer, a
 compression gauge, a multi meter,
 an oscilloscope, a vacuum gauge,
 and other tools
Some performance factors affected by
a tune-up are…
   Engine power acceleration
   Fuel consumption
   Exhaust emissions
   Smoothness of engine operation
   Ease of starting
   Engine service life
      General Tune-Up Rules
   It is important to gather engine and vehicle
    performance info before performing the
    tune-up because this gives you clues on
    what you need to investigate or replace.
   It is important to bring the engine up to full
    operating temperature prior to diagnosing
    an operating condition because when the
    engine is cold you cannot obtain accurate
    test results.
   Its important to maintain a vehicles service
    records because if a problem occurs you
    can check your record to correct the
    trouble.
        Tune-up safety rules
   It is important for the battery to be
    disconnected before maintenance so it
    does not accidentally crank the engine or
    electrical fire.
Tune-up safety rules to follow
   Wear eye protection
   Set parking break
   Place vent hose on exhaust pipe
   Disconnect battery
Typical tune-up procedures
   Battery problems-dirty case top, corroded terminals, and physical damage
   Air cleaner problems –clogged or contaminated filter, inoperative air flaps
    or disconnected vacuum hoses.
   Belt problems- looseness, fraying, and slippage.
   Low fluid levels- engine oil, brake fluid, power steering fluid, ect.
   Deteriorated hoses- hardened or softened cooling system, fuel system, and
    vacuum hoses.
   Poor electrical connections-loose or corroded connections : frayed,
    pinched, or burned wiring and terminals.
Three important steps in replacing
spark-plug wires are…
   To remove the spark-plug, first check that the spark-plug wires are
    numbered or located correctly in their clips. Grasping the spark-plug wire
    boot, pull the wire off the plug. Twist the boot back and forth if it sticks
    Ignition coils must be numbered before plugs can or located correctly in
    their clips. grasping the spark-plug wire boot, pull the wire off the plug.
    Twist the boot back and forth if it sticks. Ignition coils must be removed
    before plugs can be replaced. Be sure engine is cool before removing
    spark-plugs. Removing a spark-plug from a warm aluminum head can
    damage the threads in the spark-plugs holes.
Tools used to remove spark-plugs
   Swivel ratchet, an extension, and a spark –
    plug socket.
The correct colors for the tip and
insulator
   Grayish or brown= properly burning
   Black or wet= not firing or engine problem
   If the spark-plug wire is not put on the right
    cylinder spark-plug, the plug will not fire.
Oxygen sensors
   One and two wires need to be replaced at
    50,000-60,000 miles
   Heated three-wire oxygen sensors should
    be replaced at about 100,000 miles
Recommended procedures for
replacing a sensor
   Disconnect the negative battery cable.
    then, separate the sensor from the wiring
    harness by unplugging the connector.
    Never pull on the wires them selves, as
    damage may result.
Three primary adjustments
performance during a tune-up
   Pick up coil air gap adjustment
   Idle speed adjustment
   Ignition timing adjustment
Diesel engine tune-up
   Diesel engines require periodic
    maintenance similar to gasoline engines
    but don’t have spark plugs to replace or an
    ignition system.
Typical service tasks performed during
diesel engine maintenance intervals
are
   Replacing the air filter element
   Cleaning, draining, or replacing the fuel filters
   Adjusting engine idle speed
   Adjusting accelerator and governor linkage
   Inspecting the engine and related systems
   Adjusting valve and injector timing
   Changing engine oil and oil filter
   Servicing emission control systems

    maintenance intervals are specific periods ( in miles or months ) for
    component service.

				
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posted:2/12/2012
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