1. Engine Tune-Up

2. Introduction
Tune-up procedures have changed in recent years and are done as part of routine maintenance rather then correct a drivability problem New engine can run for longer periods between tune-ups. Most new engines do not require spark plug replacement for up to 100,000 KM

3. Engine Tune-up
Ensures that the engine , ignition system, fuel system and emission control systems are with in factory specification Auto manufacturers normally recommend a maintenance tune-up after a specific engine operating period, based on mileage and vehicle use

4. Minor Tune-up
Involves parts replacement and fluid replacement, filter and spark plug replacement A vehicle with 40,000 KM to 60,000Km may only require a minor tune-up

5. Minor Tune-up Typically involves these tasks
Visual inspection of the engine compartment
Replace spark plugs
Replace oil/filter/lube
Replace air/fuel filter
Ignition service points or timing
Check for fault codes

6. Major Tune-up
Besides the steps listed for a minor tune-up a major tune-up requires more diagnostic tests using a scan tool, gas analyzer or a compression gauge

7. Major Tune-up Replace drive belts
Replace brake, transmission, differential and other fluid
Replace weak engine sensors e.g. O2,
Replace spark plug wires

8. Importance of a tune-up
A tune-up is very important to the operation of an engine. It can affect:
Engine power and acceleration
Fuel consumption
Exhaust pollution
Smoothness of engine operation
Ease of starting
Engine service life

9. Tech Tip
If a computer controlled vehicle has performance problem, such as a rough idle, stalling, surging, a tune-up will not correct the condition in most cases. Performance problems in many newer vehicles are caused by the failure of an engine component, or sensor.

10. Questions

11. Spark Plugs
The spark plugs use high ignition voltage to ignite the fuel mixture between 4000 and 28,000 volts is needed to jump the gap at the electrode

12. Spark plug reach
Reach is the distance between the end of the plug threads and the seat or sealing surface on the plug shell If the reach is too long the plug electrode might contact the piston Or too short won’t reach the combustion chamber for complete burn

13. Types of Plugs
Resistor spark plug the plug wire has an internal resistance designed to reduce static in radios most newer vehicles require resistor plugs Used of Fuel injected vehicles to reduce E.M.I

14. Non Resistor spark plugs
Has a solid metal rod forming the center electrode Not very common in street applications but found on racing or off road applications

15. Spark plug Gap
Is the distance between the center electrode and the side electrode

16. Spark Plug Heat Range
Is a rating of the operating temperature of the spark plug tip Is determined by the length and diameter of the tip and the ability for the plug to transfer heat
Hot Plug: long insulator tip and will burn off deposits Cold Plug: has a short insulator tip will prevent over heating and preignition Manufactures will specify heat range

17. Hot/Cold Plugs

18. Spark Plug Replacement
Grasp the spark plug boot pull the wire off the plug will twisting back and forth
Use compressed air to remove debris away from the spark plug hole
As you remove each plug lay it out in order so you can read them
Set the spark plug gap on the new plug refer to specs.
Use anti seize on threads (aluminum head)
Use your fingers to start the plug in the hole (short piece of vacuum hose)
Once started use the socket and ratchet to tighten it up
(spark plug sockets have rubber boot inside)

19. Spark Plug Gap Gauge The style is used on a platinum tip plug
Standard Spark plug

20. Engine Compression Testing
It is frequently made during a tune-up to check the engine’s mechanical condition If a engine fails the compression test mechanical repair must be made before the tune-up

21. Compression Test
Is used to measure the amount of pressure during the engine compression stroke If the compression readings are not within spec. something is mechanically wrong with the engine It should be done anytime there is an extremely rough idle, a popping noise from the air inlet or exhaust, excessive blue smoke and blow-by

22. Exhaust Smoke Readings

23. Blown Head Gasket
A blown head gasket can cause pressure, coolant and oil leakage This blown head gasket allowed compression stroke pressure to flow into adjacent cylinder

24. Gasoline Engine Compression Test
Remove all the spark plugs so the engine can rotate easily
Block open the throttle plate this will prevent a restriction of air flow
Disable ignition system to prevent sparks
If its fuel injection it should also be disabled
Thread the compression gauge into one of the spark plug holes
Crank the engine allowing it to rotate 4 to 6 compression strokes
Write down the gauge readings and repeat these steps

25. Wet Compression Check
Should be completed if a cylinder pressure reads below specifications during a standard compression check This will help determine what engine parts are causing the problem

26. Wet Compression Test Procedure
Squirt A tablespoon full of 30 weight motor oil into each cylinder with the low pressure readings Install the pressure gauge and recheck (warning do not put too much oil in or there will be false readings )
If the compression gauge readings increase with oil in the cylinder then piston rings or cylinder is worn out If the pressure remains the same then valves or head gasket may be leaking The oil will seal a ring but not a burned valve or head gasket

27. Compression Test Results
Normal compression readings will make the gauge increase evenly to spec. The pressure should not vary more then 15 to 20 psi in each cylinder General spec for gasoline engine 125 to 175 psi Check service manual for the manufacture spec.

28. Causes of low Compression
Burned valve Burned valve seat Physical engine damage Blown head gasket Worn rings or cylinder Valve train trouble (Broken valve spring) Jumped timing chain or belt

29. Questions What is a compression test?
Why do we want to perform a compression test?
What are some examples of engine compression problems (smoke )
What is a general specification of a cylinder compression reading?
What can a Wet cylinder compression test tell us?

30. Summary
An engine tune-up returns the engine to a condition of peak performance A minor tune- up is a basic tune-up done when the engine is in good operating condition A major tune –up is more thorough and is done when the engine systems (ignition, fuel, emission ) are in a worn condition

31. Summary
Depending upon the age and condition of the vehicle any number of parts may need replacement during a tune-up With modern computer controlled vehicles never reroute wires. Keep all wires in there original location A compression test is frequently made during a tune-up to check the engine’s mechanical condition Diesel engines do not require tune-ups like gasoline engines they do not have spark plugs or ignition system to fail

32. Signs Of Engine Problems

33. Heat Range of Spark Plugs

34. Spark Plug Reach
Reach is the distance between the end of the plug threads and the seat or sealing surface on the plug shell

35. Compression Test Results
Is used to measure the amount of pressure during the engine compression stroke The pressure should not vary more then 15 to 20 psi in each cylinder A wet compression test the oil will seal a ring but not a burned valve or head gasket