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
|
| • | Refer to Important Preliminary Checks in
Symptoms
. |
| • | Refer to Visual/Physical Checks in
Symptoms
. |
| • | 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 owner accelerating too much, too often? |
|
Fuel
System
|
| • | Ensure each injector harness is connected to the correct injector/cylinder. |
| • | Check for fuel in the pressure regulator vacuum hose. |
|
Sensor/System
|
| • | Check for proper calibration of speedometer. Connect J 33431-C
(Signal Generator) to VSS electrical
connector. Turn ON the ignition and tester, monitor the speedometer. |
|
Ignition
System
|
| • | 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 coil(s), check for the
following conditions: |
| | Important: If carbon tracking is detected on a component, replace that component
and it's mate.
|
| - | Coil(s) - Cracks, carbon tracking/arcing, or a resistance value outside
the specified range. |
Coil Resistance
5000 - 8000 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
7000 ohms (7K ohms)
| | 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 faulty.
|
| - | Ignition System Wiring - Loose ignition module feed or ground
connection, or damaged system wiring. |
| • | Remove spark plugs and check for the following: |
| | Important: If carbon tracking is detected on a component, replace that component
and it's mate.
|
| - | Check the spark plugs for carbon tracking on the porcelain and pitting
on the plug wire contact. |
| - | 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
|
|
Engine
Mechanical
|
| • | Check engine mechanical for the following: |
| - | Sticking or leaking valves. |
| - | Excessive oil in combustion chamber-Leaking valve seals. |
| • | For incorrect basic engine parts. Inspect for the following: |
| • | Refer to Base Engine Misfire Diagnosis
for diagnosis procedures. |
|
Additional
Checks
|
| • | Check exhaust system for possible restriction. Check for the following: |
| - | Inspect exhaust system for damaged or collapsed pipes. |
| - | Inspect mufflers for heat distress or possible internal failure. |
|
