Bad ignition coil symptoms
Scroll through these bad ignition coil symptoms to find the one that matches your vehicle.
No start is a symptom of a bad ignition coil
The engine will crank but will not fire up. This is most likely in an ignition system with a single ignition coil. However, if the vehicle has a distributorless ignition system (DIS) or a coil on plug system, you generally won’t see a total failure to fire up during cranking that’s related to a coil pack or coil on plug failure. In those cases, you’d most likely see a fire up but rough or misfiring idle or stall.
Poor fuel economy is a symptom of a bad ignition coil
When the insulation on the windings breaks down, you can get internal shorting that greatly decreases the secondary output voltage to the spark plug. This creates a cooler spark and that affects the quality of combustion. You’ll see lower MPG, poor acceleration and possible rough idle and misfires at high RPMs/
Stalling is a symptom of a bad ignition coil
Stalling due to a failing ignition coil is most noticeable on 4-cylinder engines simply because the engine can’t keep running if 25% of it’s cylinders aren’t firing.
Misfire is a symptom of a bad ignition coil
Since the spark plug isn’t getting the proper voltage, it may not fire at all or may fire with a weak spark. Either once can cause a no-combustion or wear combustion even that results in a misfire. Ignition coil and spark plug related misfires happen most often on heavy acceleration. If your vehicle idles fine but misfires when accelerating or increasing speeds, suspect a failing ignition coil, bad ignition coil, the problem with spark plug wires or a bad spark plug.
See this post for information on how to test an ignition coil
©, 2020 Rick Muscoplat
Posted on by Rick Muscoplat