WAI offers best practice tips and advice for Ignition Timing faults and diagnosis

Ignition timing is critical to the smooth operation and efficiency of a petrol engine. When faults occur within the ignition system, they can cause drivability issues ranging from hard starts and misfires to complete no-start conditions.

Leading rotating electrics and engine management brand, WAI, shares its best practice advice on common ignition timing faults, the causes and how technicians can diagnose them quickly and accurately.

The distributor, mechanically linked to the engine’s camshaft, plays a vital role in routing high-voltage current from the ignition coil to the spark plugs in the correct firing order. It houses key components such as the rotor, cap and in some designs, the ignition pickup. Any wear or fault here can directly affect spark delivery and timing.

The Ignition Control Module is effectively the ‘brains’ of the ignition system. It receives input from the pickup coil or crankshaft position sensor and controls the ignition coil’s primary circuit, ensuring the spark is delivered at precisely the right time. As such, failures here can mimic many other faults in the ignition system and need careful diagnosis.

Common Causes of Failure

Heat can cause issues with the ICM as they are particularly sensitive to high under-bonnet temperatures, which can degrade internal circuits. Worn distributor components including rotor wobble, misfires, or worn caps are also classic failure points.

Moisture or oil contamination inside the distributor cap, or at module terminals, can cause poor connections and faulty ignition coils or weak grounds can over-stress the ICM and lead to premature failure.

Diagnosis Tips for Technicians

WAI suggests technicians use a spark tester to check for spark output  - no spark may point to a failed ICM or pickup coil. They should also inspect distributor cap and rotor for cracks, wear, or carbon tracking, plus, test pickup coil resistance with a multimeter (typically 500–1500 ohms) and ensure good continuity. On vehicles with early OBD systems, WAI says technicians should scan for codes to gain further diagnostic insight.

The brand says workshops should always apply thermal paste (not dielectric grease) to the back of the ICM where it contacts the distributor or heat sink - this ensures proper heat dissipation.

Also, when fitting a new ICM, WAI advises to always check wiring, clean grounds and verify the ignition coil is not drawing excessive current and also, confirm that the ICM and distributor match the application. Variations in wiring or design can cause frustrating no-start conditions.

With a wide range of OE-matching ignition components - from modules and distributors to sensors - WAI offers quality and coverage across thousands of vehicle applications. All parts are rigorously tested and backed by a strong warranty, giving technicians confidence in both the repair and the component.

Richard Welland, COO at WAI Global, said: “Ignition timing issues can be tricky to diagnose, but with a structured approach and the right parts, technicians can resolve problems efficiently. At WAI, we’re committed to supporting the trade with reliable ignition products and practical technical advice that helps workshops get it right first time.”