Fuel injection faults (V12)
Symptoms
Rough idle, hesitation, poor fuel economy (even worse than usual), hard starting, stalling.
Cause
The Lucas/Bosch digital fuel injection system relies on multiple sensors and vacuum lines. Common culprits include: air leaks in the intake manifold (the gaskets shrink and crack), faulty coolant temperature sensor (sends incorrect data to the ECU, causing rich or lean running), stuck injectors (varnish from old fuel), and perished vacuum hoses.
Fix
Diagnose systematically.
Check for vacuum leaks first (spray carb cleaner around joints while running, if the idle changes, you've found the leak).
Test the coolant temperature sensor.
Clean or replace injectors.
Replace all vacuum hoses (they're cheap, do them all).
Budget $500-2,000 AUD depending on what needs doing.
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