Technical Queries

Spark plug upgrades


  1. Posted on August 16th, 2019 by Rob Marshall
  2. You can spend hundreds of pounds on aftermarket bolt-on products that claim to improve your fuel consumption – some work, others are simply gimmicks. Even so, fitting quality replacement parts can have a greater relevance. The spark plug has a very hard life. It must contain forces that equate to fifty times that of gravity, […]

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The perils of cheap ignition coils


  1. Posted on August 5th, 2019 by Rob Marshall
  2. Ignition coils have been crucial to the petrol engine, even before one was used to power a horseless carriage and are still vital today. Their role is to provide a high voltage spark that is used to jump across a gap on a spark plug, to ignite the petrol and air mixture. Without a decent […]

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Fitting spark plugs to a GDI engine


  1. Posted on May 10th, 2019 by Rob Marshall
  2. While many of us leave car maintenance to garages, many owners are technically-interested in what goes on beneath their bonnets, even if they choose not to join the rising number of DIYers who like to get their hands dirty. The humble spark plug is one of the most critical of car components, yet is one […]

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Be wary of DPF additive overdosing


  1. Posted on May 2nd, 2019 by Rob Marshall
  2. We have heard recently of problems occurring, when drivers dose additives into their diesel cars to help clear a partially-blocked diesel particulate filter (DPF), as pictured. Subsequent problems occur not due to the additive itself but because the operator does not follow the instructions.   DPF additive problems The additives work by promoting higher temperatures […]

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How to test battery health


  1. Posted on January 7th, 2019 by Rob Marshall
  2.   Several GEM members have called our technical helpline recently, asking why a battery that has a healthy voltage can seem to be unable start an engine from cold. A voltage test does not tell the whole story and this is why:   State of Charge vs. State of Health Taking a voltage reading will […]

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Will your car make you ill?


  1. Posted on December 11th, 2018 by Rob Marshall
  2. According to Volkswagen Commercial Vehicles, drivers are at risk of breathing-in allergens that are trapped in vehicle cabin filters, after the summer’s pollen count hit a 12 year high between late-March and early-September.   Cabin filters, also called ‘pollen filters’, prevent a variety of particulates from entering a vehicle’s interior. This ranges from seeds and […]

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Why you need to replace old HID headlight bulbs


  1. Posted on December 4th, 2018 by Rob Marshall
  2.   One of the many advantages with High Intensity Discharge lamps, as opposed to filament bulbs, is that they last longer – or so we thought. As more cars have been equipped with them from new, it has been noticed that, while HIDs do not fail suddenly like a traditional filament light bulb, their output […]

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Brakes become top killer defect


  1. Posted on November 30th, 2018 by Rob Marshall
  2. According to the Department of Transport, mechanical defects caused 1,539 road traffic incidents last year, leading to 359 serious injuries and 32 deaths.   Faulty brakes accounted for 570 accidents last year, 129 serious injuries and nine deaths, eclipsing defective/ill maintained tyres as the second highest mechanical defect.   Lack of Access The main problem […]

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Sensors lead the way in warranty claim


  1. Posted on October 29th, 2018 by Rob Marshall
  2. A report that says sensors have pipped alternators to become a top warranty claim (for those sold by the RAC dealer network) came as little surprise to us, when the news hit GEM’s technical helpdesk. There are several reasons for this, such as virtually everything mechanical being influenced, or controlled, entirely by electronics that depend […]

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Why has re-gassing air conditioning become so expensive?


  1. Posted on August 10th, 2018 by Rob Marshall
  2. We have received members comments on how air conditioning regassing has become considerably more expensive, especially during this summer. While you could be sceptical and comment that unscrupulous garage owners have bumped-up their prices during the summer heat, the truth is somewhat different. Saving the planet or an air ‘con’? Air conditioning gas is a […]

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