A Spark Transfer International (STI) Coil on Plug (COP) Warranty and Diagnosis
Karlyn Industries/STI distributes high-quality COP components. The manufacturer utilizes independent engineers to monitor their coils and test warranties. Most coils that are returned DO NOT have a problem. Rough running engines that set misfire codes can have multiple causes. It is the responsibility of the dealer/installer of Karlyn STI products to verify that the following items of inspection have been performed, in order to comply with warranty replacement.
General misfire codes are most likely due to an intake vacuum leak or fuel delivery problem. Misfire codes identifying a particular cylinder are usually due to a fouled spark plug, dirty or dead fuel injector or loss of compression in the cylinder (burned or bent valve, weak or broken valve spring, or leaky head gasket.)
If the crankshaft position sensor fails, the loss of the basic timing signal will prevent the system from generating a spark and the engine will not start or run. A failed driver circuit within the powertrain control module (PCM) can kill an individual coil and prevent that cylinder from firing. Replacing the coil without addressing the cause will only result in another damaged coil.
Misfire codes can also be triggered from a damaged wire harness due to poor grounds. Inspect the wire harness carefully. You may have to cut back the insulation to verify that there is no corrosion or melting of the wire harness due to poor grounds.
A faulty harness can cause the coil to fail. If you simply install a new COP, it may seem like you have corrected the problem but, merely replacing the coil without repairing the grounding problem may result in future coil failures.
In summary, it is important to remember that ignition misfire can also be caused by other factors such as worn or fouled spark plugs, loose or damaged coil connectors or terminals, dirty fuel injectors, low fuel pressure, intake vacuum leaks, loss of compression in a cylinder, even a tank full of "bad" gas contaminated with water. These other possibilities should all be ruled out before a COP unit is replaced.
Note: A fouled spark plug can damage the COP. Karlyn STI recommends that you always replace the spark plugs when you replace the COP units & that all the ignition coils be replaced at the same time. As a form of preventive maintenance, the manufacturer suggests this be done every 60,000 miles. Karlyn STI warrants their coils to be free from factory defects for the period of 12 months or 12,000 miles.
The main goal here is a real solution to your ignition problem which will result in happy customers. Temporary solutions will only result in the return of non-defective parts and in unhappy customers who will continue to have the same problem.