Checks
| Action
|
DEFINITION: Fuel
economy, as measure by an actual road test is noticeably lower than
expected. Also, economy is noticeably lower on this vehicle than at
one time, as previously shown by an actual road test.
|
Preliminary
|
• | Check the owners driving habits. |
- | Excessive vehicle weight loads |
|
Sensor/System
|
• | Check the throttle body, throttle position (TP) sensor, and accelerator
cables for proper operation. |
• | Check the knock system (KS) for excessive spark retard. |
|
Fuel
System
|
• | Check the fuel injectors. Refer to the following: |
• | Check for fuel in the pressure regulator. |
• | Check the minimum idle speed. |
• | Check for items that cause the engine to run rich. |
|
Ignition
System
|
• | Check for proper ignition control (IC) circuit connections at
each ignition module assembly. |
• | Check for proper ignition voltage output using the J 26792
Spark Tester . |
• | Check the ignition coils for cracks, or damage. |
• | Check for a missing or damaged ignition module assembly grounding
spring. |
|
Engine
Cooling
|
• | Check for an incorrect or malfunctioning engine coolant thermostat.
Refer to
Thermostat Diagnosis
in Engine Cooling. |
|
Engine
Mechanical
|
- | Sticking or leaking valves |
- | Broken or weak valve springs |
- | Excessive oil in the combustion chamber-leaking valve seals |
• | Check for incorrect basic engine parts. Inspect the following: |
|
Additional
Checks
|
• | Check the exhaust system for possible restrictions. |
|