For 1990-2009 cars

## Poor Fuel Economy Petrol

Checks | Action
--- | ---
DEFINITION: Fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, the current fuel economy is noticeably lower than the vehicle's previous fuel economy, as shown by an actual road test.
Preliminary Checks |

• | Refer to Important Preliminary Checks in Symptoms - Engine Controls .

• | Inspect the air filter for correct type and for dirt or restriction.

• | Inspect the vacuum hoses for leaks, restrictions and correct connections as shown on the vehicle emission control information (VECI) label.

• | Review the vehicle operators driving habits for the following items:

- | The A/C compressor clutch being engaged all the time

- | Excessive idling or stop and go driving

- | Correct tyre inflation

- | Excessively heavy loads being carried

- | Too much acceleration, too often

Advise vehicle operator to fill the fuel tank and recheck fuel economy.

Fuel System Checks |

• | Test the fuel pressure. Refer to Fuel System Diagnosis

• | Inspect for fuel system leakage.

Sensor Checks | Test the engine coolant temperature (ECT) sensor for correct operation by performing the following:

1. Allow the engine temperature to reach ambient air temperature by leaving the engine OFF for several hours, overnight for most accurate results.
2. Turn the ignition ON while leaving the engine OFF.
3. Using a scan tool compare the ECT and intake air temperature (IAT) sensors displayed temperature.

The sensors should be within 3°C (5°F) of each other.

4. Replace the ECT sensor or repair the ECT sensor circuit if the ECT is not near the expected value.

Ignition System Checks |

• | Remove and inspect the spark plugs for the following conditions:

- | Wet plugs

- | Cracks

- | Wear

- | Incorrect gap

- | Burned electrodes

- | Heavy deposits

• | Test for an open ignition control (IC) circuit.

• | Inspect the spark plug wires for the following:

- | Cracking

- | Hardness

- | Correct connections and routing

| Important:: More timing advance is required to operate the vehicle on LPG than on petrol.

• | Test for correct operation of the Knock Sensor system.