Checks
| Action
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DEFINITION: Fuel economy,
as measured by an actual road test is noticeably lower than expected. Also,
economy is noticeably lower than it was on this vehicle at one time,
as previously shown by an actual road test.
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Preliminary
|
| • | Refer to Important Preliminary Checks |
| • | Refer to Visual/Physical Checks. |
| • | Check owners driving habits. |
| - | Is A/C ON full time (Defroster mode ON)? |
| - | Are tires at correct pressure? |
| - | Are excessively heavy loads being carried? |
| - | Is acceleration too much, too often? |
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Fuel System
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| • | Check for incorrect fuel pressure. |
| • | Check the fuel injectors. |
| • | Ensure each injector harness is connected to the correct injector/cylinder. |
| • | Check for fuel in the pressure regulator vacuum hose. |
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Sensor/System
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| • | Check the intake system and crankcase for air leaks. |
| • | Check for proper calibration of speedometer. Connect J 33431-B
(Signal Generator) to VSS electrical connector. Ignition ON, tester ON and
monitor the speedometer. |
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Ignition System
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| • | Check for proper ignition voltage output using the following steps: |
| - | Clip the spark tester J 26792
to engine ground. |
| - | Connect one end of a spark plug wire to the spark tester; leave
the other end of the spark plug wire to the coil being tested. |
| - | Connect one end of another spark plug wire to the other coil tower;
connect the other end of the spark plug wire to ground. |
| - | Crank the engine while observing the spark tester; a crisp blue
spark should be observed. |
| - | Repeat the above steps for each coil. |
| • | If adequate spark is not present at the coils, check for the following
conditions: |
| - | Coils - Cracks, carbon tracking/arcing, or a resistance value
outside the specified range. |
Coil Secondary Resistance
5000 - 8000 ohms (5K - 8K ohms) | - | Spark Plug wires - Signs of arcing/cross firing, cracks, carbon
tracking, plug boot damage, pinched, incorrect routing, or a resistance greater
than the specified value. |
VIN 1 Spark Plug Wires Resistance
3280 - 4921 ohms per meter (1000 - 1500 ohms per foot).
VIN K Spark Plug Wires Resistance
3280 - 4921 ohms per meter (1000 - 1500 ohms per foot).
| | Important: Spraying the secondary ignition wires with a light mist of water may
help locate an intermittent problem. Ignition components will arc to ground
when a secondary component is malfunctioning.
|
| - | Malfunctioning ignition control module. |
| - | Ignition System Wiring - Loose ignition module feed or ground
connection, or damaged system wiring. |
| • | Remove spark plugs and check 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. |
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Engine Cooling System
|
| • | Check engine coolant level for being low. |
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Engine Mechanical
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| • | Check engine mechanical for the following: |
| - | Sticking or leaking valves. |
| - | Excessive oil in combustion chamber-Leaking valve seals.
Refer to Oil Consumption Diagnosis |
| • | For incorrect basic engine parts. Inspect for the following: |
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Additional Checks
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| • | Check the exhaust system for a possible restriction. |
| - | Inspect exhaust system for damaged or collapsed pipes. |
| - | Inspect mufflers for heat distress or possible internal failure. |
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