Fault Diagnosis, Poor Driveability

FAULT DIAGNOSIS, POOR DRIVEABILITY
General fault diagnosis for poor driveablity is difficult to carry out. However, a number of tips are given below.

1. Cold-starting and warming-up problems can be caused by the coolant temperature sensor indicating an engine temperature that is too high.

Use an ISAT and read off the coolant temperature in Trionic, then contact Integrated Central Electronics (ICE) and use the ICE's coolant temperature as a reference. The difference between these two temperature readings may be ± 5°C because of tolerances. If Trionic does not have a reference ground from crimped connection J68 to pin 66, Trionic shows a coolant temperature that is approx. 20°C too high even if the temperature sensor is OK.

2. If the pressure sensor does not produce a correct voltage throughout the pressure range, this too can cause driveablity problems. Check also the hose to the pressure sensor for leaks.

3. Check the hose to the fuel pressure regulator for leaks.

4. The electrode gap of the spark plugs is of great significance to the running of the engine.

A gap that is too large causes misfiring at full load.

A gap that is too small causes unsteady idling.

5. Check the color of the insulator base of the spark plugs. If any spark plug has a distinctly lighter color, this may be due to this cylinder receiving a fuel/air mixture that is too lean.

If so, carry out flow measurement on the injectors.