Compression Tests + Spark Plugs Flashcards
How much volts does a spark plug produce?
3000 - 15000 volts
What is the purpose of an ignition system?
- it ignites the air/fuel at the correct time.
What are the three common varieties of ignition systems?
- distributor ignition system: 1 coil for all spark plugs
- distributorless ignition systems: 1 coil for every PAIR of spark plugs.
- direct ignition system: 1 coil per spark plug.
What is the purpose of the ignition coil?
- transform the low voltage from the battery into high voltage to spark the plugs.
What could be the result of compression loss?
- leaking valve
- carbon built up on valves
- worn compression rings
- blown head gasket
- burnt valves.
What is this reading telling you?
Engine Spec’s: 150 PSI +/- 10%
Cylinder #1: 150 PSI
Cylinder #2: 160 PSI
Cylinder #3: 70 PSI
Cylinder #4: 150 PSI
leaking valve
What is this reading telling you?
Engine Spec’s: 140 PSI +/- 10%
Cylinder #1: 90 PSI
Cylinder #2: 105 PSI
Cylinder #3: 100 PSI
Cylinder #4: 105 PSI
worn compression rings and cylinders
Engine Spec’s: 160 PSI +/- 10%
Cylinder #1: 20 PSI
Cylinder #2: 20 PSI
Cylinder #3: 150 PSI
Cylinder #4: 140 PSI
Blown head gasket
Engine Spec’s: 150 PSI +/- 10%
Cylinder #1: 190 PSI
Cylinder #2: 210 PSI
Cylinder #3: 200 PSI
Cylinder #4: 195 PSI
Excessive carbon built up
What are the different types of spark plugs?
traditional style: nickel plated copper plug (can be readjusted).
platinum plugs: does not require gapping
iridium plug: does not require gapping
Where can you find spark plug specs for a vehicle?
under the hood, or through mitchel
How should gapping be done with spark plugs?
- use a spark plug gapping tool
- the L shape ground is what will be bent (not the electrode)
- check the gap with a feeler gage
