'99 Merc Grand Marquis mileage 87K, as the weather warms, I get a distinct "spark knock" or "ping" when accelerating or putting a load on the engine. It gets worse as the weather warms, especially when I use the a/c. During the winter, I hardly ever notice it. I have tuned the engine, new fuel pump, regular maintenance, but can't solve the problem. I burn 89 octane gas, and that helps, but doesn't solve it. A friend said something about getting the car's computer "flashed". ??? I'd love to get this fixed without having to burn premium gas all the time. Any thoughts?
Thanks much,
Thanks much,
Mar 21, 2007 at 8:59 AM