Checks
| Action
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DEFINITION: Fuel
economy, as measured by an actual road test is noticeably lower than expected.
Also, fuel economy is noticeably lower than the economy was on this
vehicle at one time, as previously shown by an actual road test.
|
Preliminary
|
| • | Check owners driving habits. |
| - | Is A/C ON full time, or the defroster mode ON? |
| - | Are tires at correct pressure? |
| - | Are excessively heavy loads being carried? |
| - | Is acceleration too much, too often? |
|
Fuel System
|
| • | Inspect for fuel in the pressure regulator vacuum hose. |
|
Sensor/System
|
| • | Inspect the intake system and crankcase for air leaks. |
| • | Test for proper calibration of speedometer. Connect a J 33431-C
Signal Generator to vehicle speed
sensor (VSS) electrical connector. Ignition ON, tester ON and monitor the
speedometer. |
|
Ignition System
|
| • | Test for proper ignition voltage output using the following steps: |
| - | 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 adequate spark is not present at the coils, test for the following
conditions: |
| - | Coils--Evidence of carbon tracking or arcing, cracks in the
coils, or a resistance value outside the specified range: |
Coil Secondary Resistance
5000-8000 ohms (5K-8K ohms)
| | 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.
|
| - | Spark plug wires--Inspect for the following conditions: |
| • | Evidence of cross firing |
| - | Spark plug wires--Inspect for a resistance value more than
the specified value: |
Spark Plug Wires Resistance
3280-4921 ohms/meter (1000-1500 ohms/ft) | - | Malfunctioning ignition control module (ICM) |
| - | Ignition system wiring--Loose ignition module feed or ground
connection, or damaged system wiring. |
| • | Remove spark plugs and inspect for the following conditions: |
| - | Burned or damaged electrodes |
| • | If spark plugs are gas or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. |
|
Engine
Cooling System
|
| • | Test engine coolant level for a low condition. |
| • | Test for incorrect or malfunctioning engine thermostat. Refer
to
Engine Overheating
in Engine
Cooling. |
|
Engine Mechanical
|
| • | Test for the following: |
| - | Sticking or leaking valves |
| - | Excess oil in combustion chamber-Inspect for leaking valve
seals. |
| • | Inspect for incorrect engine parts, such as the following basic
components: |
|
Additional
Tests
|
| • | Inspect the exhaust system for a possible restriction in the following
components: |
| - | Damaged or collapsed pipes |
| - | Heat distress or possible internal failure in the muffler |
| - | Plugged 3-way catalytic converter--Test for possible plugged
conditions. Refer to
Restricted Exhaust
in Engine Exhaust. |
|
