Is your engine juddering, does it run rough, has a loss of power or misfires?

Is your engine management warning light (EML) on, or just not starting? Your coil may not be sparking. If your vehicle has a running problem, from our workshop in Chatham in Medway we have the knowledge and capability to test and see if a coil is working.

The Technical Bit Explained:

The coil is a type of electrical transformer that increases a vehicle’s battery supply to a point that allows the spark plug to spark and ignite the air and fuel mix. It’s ability to increase the power is the only similarity because unlike a power transformer, an ignition coil has an open magnetic circuit and the iron core does not form a closed loop around the windings. The energy that is stored in the magnetic field of the core is the energy that is transferred to the spark plug.

The Modern Systems:

In a modern system the ignition is instead electronically controlled. Much smaller coils are used with one coil for each spark plug or one coil serving two spark plugs.

A large ignition coil produces about 40 kV which is quite amazing to think that this power has originally come from a 12 volt battery. These coils may be remotely mounted or they may be placed on top of the spark plug (coil-on-plug or Direct Ignition).

Where coils are individually applied per cylinder, they may all be contained in a single molded block with multiple high-tension terminals. This is commonly called a coil-pack.

The Results of a Bad Coil:

A breakdown in the coil’s internal workings can result in a weak spark making the engine misfire and cause rough running. It could give bad fuel consumption or a loss of power. Total failure of a coil can cause the vehicle not to start at all.

Why Choose Auto Experts Medway?

We at Auto Experts Medway in Medway have established a superb reputation for high quality vehicle repair services, refer to our testimonials from our customers from Chatham, Gillingham and Rochester on our testimonial page.

Auto Experts Medway Chatham in Medway can plug a scanner into your vehicle and diagnose the fault. We are in Medway towns close to the centre of Chatham.


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With two bays we are one of the largest testing stations in Medway. Use our booking request form to book your MOT and one of our team will get back to you to confirm.




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