What are Thunderbird COPs and what do I do when they fail?
COP is an abbreviation for ‘Coil on Plug.’ It is a combination of a standard spark plug and an ignition coil, built in to a single unit. Older vehicles used spark plugs and a distributor to provide ignition spark to fuel for combustion. COPs eliminate the need for a distributor and individual spark plug wires by combing the functions of both into a single, stand alone components. The ignition coil is the part of the ignition system that generates high voltage to the spark plugs in order to ignite the air/fuel mixture in the cylinder. Ignition coils are compact electrical transformers that boost voltage as high as 40,000 volts, which is the level needed for proper combustion. The part is made up of two sets of windings that operate together to generate the required output voltage. One of the windings, called the primary side, has fewer windings than another one, known as the secondary side. Current running from the battery into the primary side creates a magnetic field. When the coil is signaled by the engine control module, the primary side magnetic field collapses and a surge of electricity flows to the secondary side, where the current necessary for combustion is developed and sent to the spark plug. When an ignition coil fails, it can lead to serious engine problems, including misfiring, rough idling, diminished acceleration, and poor engine performance.
How do I know if I have a COP problem?
COP issues are typically characterized by rough idling, engine misfires, or a more severe loss of power which may cause the Thunderbird to go into ‘limp’ mode … capable of only slow speeds until the problem is corrected. A COP failure may or may not be accompanied by an error code on the dashboard, but when the problem surfaces, it is typically quite obvious to the driver.
Why do COPs fail?
While there are a number of possible reasons for COP failures, they tend to relate to leakage of either water or oil, or both into the cylinder heads. This can be caused by a ruptured valve cover or windshield wiper cover gasket, however, fluids may find their way into the plug well other ways. Whatever the cause, once a COP fails it must be replaced for proper engine operation. Failure to do so can result in damage to the catalytic convertor, which can be very costly to replace.
When do COP issues typically arise?
COP issues tend to appear on Thunderbirds with 20,000-30,000 or more miles, however, they can fail at any time depending on the age and mileage of the car. Some Thunderbird owners have driver 50,000 miles or more without a COP failure, while others have experienced problems with as few as 15,000 miles on their cars.
What do I do if I have I COP problem?
If you have a COP problem, you will know something is wrong with your Thunderbird, but you may not know if it’s the COP. As mentioned previously, you’ll experience rough idling and misfiring while driving. If you ignore the rough running and continue to drive, you may cause damage to your catalytic convertor or other engine components. If your Thunderbird goes into ‘limp’ mode, you’ll probably have drive it or have it towed to a mechanic or your Ford dealer. If you’re a ‘do-it-yourselfer,’ and have the skills, tools and patience, here’s a link to a step-by-step guide to replacing the coils: http://www.justanswer.com/ford/3tllc-step-step-change-coil-plug-2002-thunderbird.html
While COP issues can occur with all 2002-2005 Thunderbirds, the 2002 was not covered by the Ford TSB, or ‘Technical Service Bulletin” alerting owners and dealers to the problem. 2003 Thunderbirds were given extended factory coverage to 10 years / 100,000 miles. Details appeared in a Customer satisfaction Program -07M07, from July 2007 that covered the 2003 year. A update to this Program 07M07, Supplement #1 dated May, 2008 extended the coverage to include the 2004 and 2005 models. The 2003 coverage is for coils and gaskets, the 2004 & 2005 covers the coil only due to a redesign in ’04 & ’05 that was supposed to eliminate the leaking gasket issue. 2003 and later Thunderbirds were eligible for replacement of failed COPs under the TSB, saving affected owners a substantial amount of money. Some T-Bird owners have had COPs replaced on more than one occasion, depending on which COP failed and when. COPs are also covered by various Ford Extended Service Plans, which are still available for qualifying 2004 and 2005 Thunderbirds.
But what if my Thunderbird is not covered by either a TSB or an extended service plan?
Depending on how many COPs need replacement, and where you have repairs performed, the cost to replace all eight COPs can run $ 800 or more. Independent repair shops and mechanics can often replace COPs for less than a Ford dealer will charge. Ford dealers use only Ford OEM replacement parts, which typically cost more than aftermarket COPs which are available from a number of different manufacturers.
When you need to replace one or more ignition coils, we recommend Ford Motorcraft Ignition Coils for the highest-quality and most reliable OEM replacement. There are, however, many aftermarket replacement coils available in all price ranges.
