Part of Unit: Engine Fundamentals
Lesson Plan Overview / Details
Students will learn to diagnose and repair ignition problems. Students will learn that there are some common problems to look for, such as a loose spark plug wire or an arcing spark plug wire, when attempting this service.
- Class time
- 55 Minutes
California Career and Technical Education Standards
- T.C.C1.1 Know and understand common environmental conservation practices and their applic...
- T.C.C1.4 Evaluate the advantages and disadvantages of existing, new, and emerging systems...
- T.C.C2.1 Understand and use appropriate tools and equipment, such as wrenches, sockets, a...
- T.C.C3.7 Perform necessary procedures to maintain, diagnose, service and repair vehicle o...
- T.C.C7.1 Understand how to maintain, diagnose, and repair electrical systems.
California Academic Content Standards (Reinforced)
Objectives and Goals
Students will be able to diagnose common ignition problems and service an ignition system properly.
Activities in this Lesson
- Hook - Hooks / Set
Do you ever wonder why a car backfires while driving down the street? This question will be answered today. I would like each student to write down three reasons why a car backfires and we will make comparison at the end of the class while working in groups. Our findings will be all different but interesting.
- Lecture - Lecture
Some of today’s engines use spark plugs designed to last for up to 100,000 miles, but most spark plugs need to be changed about every 30,000 miles. During a tune-up, a complete set of spark plugs is usually installed. When a spark plug is dirty or has worn electrodes, a misfire can result. Symptoms of misfire are usually only noticeable at idle.
Some spark plugs have carbon resistors. Others have a semiconductor suppressor that is not energized until 1000 volts. This kind of spark plug can be checked with an ohmmeter.
When replacing spark plugs, it is important that the correct replacement is used. The code number on the spark plug tells about the hear range, thread size, type of seat, whether the tip is extended, or whether or not it has a resistor.
The spark plug gap is usually set from the factory. It is important to double-check the gap before installation. It is not unusual to find closed gaps or gaps that have changed because of rough handling.
A wire gauge can be used to check the gap. It has an arm that is used to reposition the bendable electrode on the plug.
When installing spark plugs, it is recommended to apply a little bit of anti-seize compound on the front two threads of the plug before installation. Anti-seize is especially needed on aluminum heads to prevent electrolytic action between the steel spark plug body and aluminum head.
Spark plug gaps in older cars are specified small gaps around 0.035 inches. The gaps on newer cars can vary up to 0.80 inches. It is important to look up the specification of the gap.
Removing spark plug cables must be a careful operation if cables are to be reused. The rubber boots usually become formed to the ridges on the spark plug. They must be twisted to loosen them. Handle them only by the plug boots so they do not suffer internal breaks. Changing cables one at a time will avoid accidental mixing them up in the firing order.
- Modeling - Demo / Modeling
After the lecture, I would show the students a picture of spark plugs and spark plug wires so that I can demonstrate the way the spark travels. I will also have a spark plug and a set of spark plug wires for each group of four students so that they can follow while I am demonstrating the way it functions.
- Group work - Group Work
I would have students work in groups of four taking turns explaining why and when spark plugs must be changed. I would also show and explain how to gap a spark plug, while having the students gap a spark plug as a group. It is important to demonstrate to students the proper way to install and remove spark plug wires while the students work as a group to do the same procedure.
I would pass out a hand-out to each student. On the hand-out, each student would have to identify the different parts of a sparkplug. They will also identify the names of all tools necessary to remove a spark plug and spark plug wire.
- Closure - Closure
I would have students start cleaning up shop area and put away tools. I would also do a quick review of today's lesson and answer any questions that students may have about the lesson.
I would then choose individual students and ask specific questions about today's topic.
- Assessment Types:
- Demonstrations, Observations,
I would choose one student from each group and have him explain:
- The importance of have a proper spark plug
- The right procedure of gapping a spark plug
- The proper way to install and remove a spark plug
If the chosen student needed help, other members of the group can participate with helping.