Engine Tune-UpBy 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… scan tool, 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.