Ignition Coil Tips

Ignition Coils Do’s and Don’ts

The basic function of an ignition coil is to provide adequate energy to ignite the compressed air/ fuel mixture during the compression stroke of a gasoline engine. An accurate and robust flame initiation will lead to successful combustion under all engine conditions. An electronics circuit (driver) is used to control the timing of the firing event (switch the coil on & off). Driver circuit could be integrated with the coil as one package, it could be a standalone unit as in the case of an ignition module, or could be located inside the engine controller (PCM/ECM/ECU).

When selecting an ignition coil for repair it’s important to make sure you go with a product you can trust to help deliver no comebacks. It’s important to you, it’s important to your customer… and it’s important to us. So, why Delphi ignition coils? Simple. OE quality equals reduced comebacks and satisfied customers. Delphi uses its OE engineering and heritage to deliver OE technology ignition coils for the aftermarket. The Delphi name on the box is your assurance that the product inside will deliver the performance you expect.

Below is a list of best practices when performing ignition coil repair and replacements.

Recommendation	Reason
Coils should not have any visible damage and the boot should be fully seated. While assembling coils to the engine, if noticing any visible damage like a cracked coil housing, broken anti-rotational tabs or broken connector, disregard that coil.	Any damage part could lead to a premature failure and a poorly seated boot could lead to engine misfire.
Never remove or disassemble the boot from the coil.	Disassembling the boot from coil could lead to losing the spring and / or suppressor, leading to engine misfires and RFI noise.
Do not scratch the HV towers or the coil housing.	Scratching the coil body could lead to a cracked case and / cracked HV tower which would lead to arc thru and coil failure.
Never strike any part of the ignition system with a tool or other object.	This can lead to physical damage (micro-cracking that can’t be seen), which can cause a system malfunction or failure.
Never use hammers or other striking devices to install plug wire to the coil HV tower. Installation of the plug wire to the coil HV tower should be done by hand.	The striking process could induce micro-cracking (invisible to the human eye) at the coil HV tower and could deform / damage the plug wire terminal that may lead to premature failure.
Don’t apply any non-approved material to the surface of the high voltage tower which mates with the high voltage secondary leads.	This can jeopardize the seal integrity of the mating surfaces, which in turn can create a secondary high voltage leak path and carbon tracking.
Do not permit paint or other sprayed materials to be sprayed onto the electrical connectors.	Insulating-type spray can create a high resistance or open connection. Conductive-type spray can create an electrical short condition.
Always apply the specified torque to the specified mounting thru-bolt.	Loose thru-bolts could lead to failure under vibration. Over-tightened thru-bolts could lead to cracked coil mounting ear and / or premature thru-bolt failure.
Do not support the ignition system by the wiring harness or plug wire.	These leads are not designed to support the weight of the ignition system. It can create a poor electrical connection or become disconnected allowing the system to fall and subjected to potential physical damage.
Never force feed the engine wire harness mating connector into the coil connector. Always ensure the mating connectors are entirely seated and locking mechanism is engaged. A snap should be heard / felt upon a good connection.	This maintains a proper connection and prevents intermittent electrical connections leading to an improper ignition system operation.