Checks
| Action
|
DEFINITION: Fuel
economy, as measured by an actual road test is noticeably lower than expected.
Also, economy is noticeably lower than the fuel economy was on this
vehicle at one time, as previously shown by an actual road test.
|
Preliminary
|
| • | Refer to Important Preliminary Checks. |
| • | Refer to Visual/Physical Checks. |
| • | Review the owner's 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? |
|
Fuel System
|
| • | Inspect the fuel injectors using the following tests: |
| • | Ensure each injector harness is connected to the correct injector/cylinder. |
| • | Inspect for fuel in the pressure regulator vacuum hose. |
|
Sensor/System
|
| • | Inspect the air intake system and crankcase for air leaks. |
| • | Test for proper calibration of speedometer. Connect the J 33431-C
Signal Generator and
Instrument Panel Tester to the vehicle speed sensor (VSS) electrical connector.
Turn ON the ignition, with the engine OFF. With the tester ON, 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 J 26792
. Connect the other end of the spark
plug wire 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 J 26792
. A spark should be observed. |
| - | Repeat the above steps for each coil. |
| • | If spark is not present at the coils, test for the following
conditions: |
| - | Coils--Cracks, carbon tracking/arcing, or a secondary resistance
value outside the specified range |
Coil Resistance
5,000-8,000 ohms (5K-8K ohms) | - | Spark plug wires--Signs of arcing/cross firing, cracks, carbon
tracking, plug boot damage, pinched, improper routing, or a resistance value
outside the specified range |
Spark Plug Wire Resistance
9840 ohms per meter (3000 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 faulty.
|
| - | Ignition system wiring--Loose ignition module feed or ground
connection, or damaged system wiring |
| • | Remove spark plugs and inspect for the following: |
| - | Burned or damaged electrodes |
| - | Improper heat range or reach |
| • | If spark plugs are gas or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. |
|
Engine
Cooling System
|
| • | Inspect the engine coolant level for being low. Refer to
Loss of Coolant
in Engine Cooling. |
| • | Inspect and test for an incorrect or faulty engine thermostat.
Refer to
Thermostat Diagnosis
in Engine
Cooling. |
|
Engine Mechanical
|
| • | Inspect engine mechanical 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: |
Refer to
Symptoms - Engine Mechanical
in
Engine Mechanical 3.8L.
|
Additional Checks
|
| • | Test the exhaust system for a possible restriction. Inspect for
the following: |
| - | Inspect the exhaust system for damaged or collapsed pipes. |
| - | Inspect the mufflers for heat distress or possible internal failure. |
| - | For possible plugged 3-way catalytic converter--Refer to
Restricted Exhaust
in Engine Exhaust. |
|
