Ford Falcon: Barra six coil-pack breakdown causing a cylinder misfire (BA to FG X)

The Barra six runs one ignition coil per cylinder sitting directly on top of each spark plug. The moulded resin around the windings hardens with heat and develops hairline cracks - often too fine to see - and the spark leaks out through the body of the coil into the cylinder head instead of jumping the plug gap. That cylinder stops firing under load, the engine light comes on, and raw fuel goes down the exhaust. Left alone the unburnt fuel cooks the catalytic converter, which is the bill that actually hurts. Coils on these engines run at very high voltage, higher again on the turbo and V8 cars, and specialists report cheap replacement coils failing again within 20,000 km, so the brand fitted matters. They are normally replaced as a set of six along with the spark plugs.

• Shudder or stumble under load, worst uphill or in damp weather
• Engine warning light on, or flashing during acceleration
• Rough lumpy idle, sometimes only when cold or damp
• Clear loss of power and a jerky feel on part throttle
• Smell of unburnt fuel from the exhaust

1. 1

   Start the engine from cold, rest your hand on the gear lever and feel for a regular shake or hesitation that a healthy six simply does not have.

2. 2

   Watch the engine warning light: it should light up with the key and go out once running.

3. 3

   If it stays on, or comes on during your drive, the car needs diagnosis before you buy, and if it flashes, stop driving, because a flashing light means a misfire that is actively cooking the catalytic converter.

4. 4

   On the test drive get it to around 2,000 rpm in a high gear and squeeze the accelerator gently, because a coil that is breaking down shows up as a shudder under load long before it shows at idle.

5. 5

   Open the bonnet and look along the top of the engine at the six coils sitting on the plugs; cracked, chalky or oil-soaked coil bodies, or one coil that is obviously newer than the other five, tells you a story.

6. 6

   Ask when the coils and spark plugs were last done and whether genuine or budget parts were used.

Parts involved: Ignition coil.

$250 to $950 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “When were the coil packs and spark plugs last replaced, and with what brand?”
• “Is the engine light on now, or has it been on recently?”
• “Does it misfire when it is damp, or after the engine bay has been washed?”
• “Has the catalytic converter ever been replaced?”

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

• Autotrad 'BA BF Falcon Ignition Coils' technical article
• MotoringBox 'Barra Misfire! Replacing Coil Packs & Spark Plugs on my BA XR6 Turbo'
• P & G Motors (Seven Hills) 'BA Falcon missing at idle and underload'