Checks
| Action
|
DEFINITION: Fuel
economy, as measured by an actual road test is noticeably lower
than expected. Also, economy is noticeably
lower than economy was on this vehicle at one time,
as previously shown by an actual road test.
|
Preliminary
|
| • | Check the owner's driving habits. |
| - | Is the A/C on full-time? |
| - | Are the tires at the correct pressure? |
| - | Are there excessively heavy loads being carried? |
| - | Is acceleration too much or too often? |
|
Fuel System
|
| • | Check for fuel in the pressure regulator vacuum hose. |
|
Sensor/System
|
| • | Check the intake system and the crankcase for air leaks. |
| • | Check for correct calibration of the speedometer. Connect aJ 33431-C
Signal Generator
to the vehicle speed sensor (VSS) electrical connector. Turn the tester
ON and monitor the speedometer. |
|
Ignition System
|
| • | Check for the proper ignition voltage output using the following
procedure: |
| - | Clip the J 26792
Spark Tester to engine ground. |
| - | Connect one end of a spark plug wire to the spark tester. Leave
the other end of the spark plug wire connected to the coil being tested. |
| - | Connect another spark plug wire between the remaining tower of
the coil being tested and ground. |
| - | Crank the engine while observing the spark tester. A spark should
be observed. |
| - | Repeat the above steps for each coil. |
| • | If spark is not present at the coils, check for the following
conditions: |
| | Important:: If carbon tracing is detected on any component, replace that component
and the component's mate.
|
| - | Inspect the coils for cracks, carbon tracking/arcing, or a resistance
value outside the specified range. |
Coil Secondary Resistance
5,000-8,000 ohms | - | Inspect the spark plug wires for signs of arcing or cross firing,
cracks, carbon tracking, plug boot damage, pinched wires, incorrect
routing, or a resistance more than
the specified value. |
Spark Plug Wire Resistance
3280-4921 ohms per meter (1,000-1500 ohms
per foot)
| | Important: Spraying the secondary ignition wires with a light mist of water may
help locate an intermittent condition. Ignition components will
arc to ground when a secondary
component is malfunctioning.
|
| - | Check for a malfunctioning ignition control module (ICM). |
| - | Check the ignition system wiring for a loose ignition module feed,
ground connection, or damaged system wiring. |
| • | Remove the spark plugs. |
| • | Inspect the spark plugs for the following conditions: |
| | Important:: If carbon tracing is detected on any component, replace that component
and the component's mate.
|
| - | Check the spark plugs for signs of carbon tracing on the porcelain or
arcing at the plug wire contact. |
| - | Check the spark plugs for incorrect gap. Refer to
Maintenance Items
in Maintenance and Lubrication. |
| - | Check the spark plugs for damaged electrodes. |
| - | Check the spark plugs for incorrect heat range. Refer to
Maintenance Items
in Maintenance
and Lubrication. |
| • | If the spark plugs are gas or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. |
|
Engine Cooling System
|
| • | Check engine coolant level. |
| • | Check for an incorrect or malfunctioning engine thermostat. Refer
to
Thermostat Diagnosis
in
Engine Cooling. |
|
Engine Mechanical
|
| • | Check engine mechanical for the following: |
| - | Inspect for worn camshaft lobes. |
| - | Check the valve timing. |
| - | Check for bent push rods. |
| - | Check for worn rocker arms. |
| - | Check for broken valve springs. |
| - | Check for excess oil in combustion chamber and leaking
valve seals. |
| • | Inspect for incorrect engine parts, such as the following basic
components: |
|
Additional Checks
|
| • | Check the exhaust system for a restriction. |
| - | Inspect the exhaust system for damaged or collapsed pipes. |
| - | Inspect the mufflers for heat distress or internal failure. |
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