Review on 🚘 Mercury Optimax Ignition Coil 339-879984T00 from Automotive Authority - Improved SEO by Jorge Kumar

If I could rate ZERO stars I would except they at least require a signature for delivery. This is almost the only factor of salvation. Firstly, I don't even know if I received the right product because the devices are packaged in a single box with no part numbers and definitely no identification. Yes, they look identical to the original product, but that doesn't mean anything at all. Secondly, these coils are sold as non-genuine units, with the description saying "This ignition coil meets or exceeds OEM specs." After receiving the package, I took a couple of coils and checked the resistance at the contacts with one multimeter. I have the displayed values on a diagram from the current Mercury Service Manual. They went out of range immediately, and some tests showed complete continuity where it should be between 12 and 20 kΩ. I suspect other positive feedback on this item has not actually been tested with a multimeter and/or has not really validated the performance criteria. According to a Mercury service bulletin, a bad coil can burn out your ECM. I called Mercury Marine direct (Wisconsin Service Support). The tech I spoke to confirmed that the resistor values have not changed with the updated part numbers and the chart I have is still valid. So I was led to believe that this aftermarket reel was either wrong, poorly finished or just not up to spec. They're over half the price of the original, but I'll be returning them and ordering the correct ones. Sometimes you really do get what you pay for.