Checks
| Action
|
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.
|
Preliminary
|
| • | Search for bulletins. |
| • | Check the owner's driving habits. |
| - | Is the A/C ON full-time (Defroster mode ON)? |
| - | Are the tires at the correct pressure? |
| - | Are excessively heavy loads being carried? |
| - | Is the acceleration too much, too often? |
|
Fuel
System
|
| • | Ensure each injector harness is connected to the correct injector
and cylinder. |
| • | Check for fuel in the pressure regulator vacuum hose. |
|
Sensor/System
|
| • | Check for proper calibration of the speedometer. Connect a J 33431-C
Signal Generator to
the vehicle speed sensor (VSS) electrical connector. Turn the ignition and
the tester ON and monitor the speedometer. |
|
Ignition
System
|
| • | Check 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. 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 spark tester. A spark should
be observed. |
| - | Repeat the above steps for each coil. |
| • | If spark is not present at the plugs, check for the following
conditions: |
| - | Check the coils for cracks, carbon tracking/arcing, or a secondary
resistance value outside the specified range. |
Coil Resistance
5000-8000 ohms (5K-8K ohms) | - | Check the spark plug wires for 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
1000-1500 ohms/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.
|
| - | Check for a defective module. |
| - | Check the ignition system wiring for a loose ignition module feed
or ground connection, or damaged system wiring. |
| • | Remove the spark plugs and check for the following: |
| | Important: If carbon tracking is detected on any component, replace that component
and the component's mate.
|
| - | Carbon tracking on the porcelain and pitting on the plug wire contact. |
| - | Burned or damaged electrodes |
| • | 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 the engine coolant level for being low. Refer to
Loss of Coolant
. |
|
Engine
Mechanical
|
| • | Check engine mechanical for the following: |
| - | Sticking or leaking valves |
| - | Excess oil in combustion chambers--Inspect for leaking valve
seals. |
| • | Refer to the appropriate misfire procedures in Engine Mechanical.
Inspect for incorrect engine parts, such as the following basic components: |
|
Additional
Checks
|
| • | Check the exhaust system for possible restriction. Check for the
following: |
| - | Inspect the exhaust system for damaged or collapsed pipes. |
| - | Inspect the mufflers for heat distress or an internal failure. |
|
