Lesson Plan Industry Sector
Transportation

**Vacuum Testing / Driveability (updated) by Michael Fleming

Lesson Plan Overview / Details

Students will learn the expected vacuum readings, good and bad, and how vacuum changes with different vehicle driving condition.

Lesson Time

Lecture, Model, Lab
3 Days

Objectives and Goals

• Students will understand how engine vacuum is related to engine load and throttle position.
• Students will learn how to use a vacuum gauge to diagnose vehicles.

Activities in this Lesson

• Student Cars - Hooks / Set

In the front of the class, have a select amount of varied weight automotive parts from a piston, to a camshaft, to a crankshaft, to a head, and then a stripped engine block. Select students one at a time to come up and carry the parts to a table at the back of the room. Start with the lightest and work to the heaviest. Afterward, ask students what they noticed. Guide the discussion to the idea of weight and load and compare it to strength and breathing. Ask them how they would measure the work or load if they were a car with the same demands. Hold up a vacuum gauge and describe its use as a diagnostic tool and a measure of engine load and throttle position.

• I always stress with my students the availability of information on the internet that was not around when I was a student.  I tell them the best technicians are the best at research, in other words, they excel at educating themselves and are capable of applying the new information to real situations. Show the students the following You Tube Video.

• Transition to direct instruction using the white board.  If you are an Engine Performance and Emissions Diagnosis class, I like to first list the smog systems that use vacuum (Intake & Ported).  For Iintake list PCV, EVAP, AIR, TAC. For ported, list EGR.

See student notes: Next draw four large columns and divide them in half. On the top draw four basic driving conditions: stop, part throttle, wide open throttle WOT, and deceleration (one in each column). The whole time, describe the loads placed on the motor and expected vacuum, engine rpm, and throttle position. Then on the second row, go back and list these conditions for each picture. Last I draw a throttle body and two vacuum gauges (Intake & Ported). In each column have the students start to anticipate what position the throttle is in and what is the expected vacuum (note that the video did not sho ported vacuum, and that it only has vacuum at part throttle).

You will find that the students start to feed you the information as you draw and they begin to predict what is happening.

• Now watching the video the second time, have students call out what the driver is doing based on the vacuum gauge readings. They should now know the driving condition, throttle position, engine load and have an idea on rpm response.

• Instructor Modeling - Demo / Modeling

Take the students out into the shop and show them the different vacuum ports on a vehicle. I prefer to show a carburated, OBDI and ODBII car to show how vacuum hose routing has evolved. Identify intake and ported vacuum ports, and use the vehicle emissions decal to trace the vacuum hoses from the source to the device they control. Next hook up a vacuum gauge to an intake manifold port and show the how vacuum reflects throttle position, engine load and rpm.

For safety, I always reinforce blocking the tires and checking the vehicle to make sure the parking brake is applied and it is in park or neutral.

• Classroom Worksheet - Lab / Shop

I find that when students study and transfer the knowledge from a textbook or study sheet, the information is remembered longer. I use our textbook from Prentice Hall Media by James Jalderman, but the attachment is from the Internet. Project the study sheet for all to see.  Stress to students that the best mechanics are the ones who are capable of doing research and then apply their new knowledge into a real situation. Give students the attached worksheet to write all the vacuum readings for varied engine problems located on the bottom of the page. Only after they drawn and labeled each example may they go out to perfom the lab exercise part.

• When four to five students have completed the drawings / labeling, give them a vacuum gauge and pliers and assign them to a vehicle. After they follow the steps in the worksheet properly, allow them to create a misfire, create a vacuum leak, or clamp a socket into the tail pipe to create a plug exhaust situation. Extra credit can be given if they recognize differences in vacuum readings with each "bug."

• I provide closure by creating dialog with the students in the group setting. After I stamped off a group on the activity, I ask the students to summarize what they have learned, and I ask for their thoughts on the usefulness of the tool (the how & when the skill would be used in an actual shop).

Assessment

The instructor should rotate through the shop activity monitoring for safety glasses, proper vacuum gauge application and diagnosis. Open ended questions will check each student's understanding. Each student should also be observed using the vacuum gauge correctly. After verification of all of these assessments, the instructor should use a slected stamp to stamp the worksheet and the completion of the skills.