Horrible backfire when I accelerate too fast/floor the car.
Hello, this problem started almost immediately after doing a sparkplug change. I decided to test out FC sparkplugs in my car. I recently switched backed to the stock FB sparkplugs and the problem still persists. I want to sell my car so I can afford a sports bike, so I would to take care of this problem as soon as possible. Any help is greatly appreciated as I would rather save my money and do the work myself.
An exact description of the problem follows: I take my car up to 3.5k before I can floor it as a result of my Mikuni dual 45mm barrel. If I immediately floor it at that RPM the car will rev up to approximately 4.5-5k RPM and then let out a horrible flaming backfire. If I immediately let up on the gas that is all that happens and it drops back to idle and then seems to run fine. However, if I continue to floor the car it will backfire repeatedly and at great speed resulting in a god awful sound and a complete lack of power. I am driving the car daily as if I do not attempt to accelerate fast there is no sign of any problems and it runs just as it always has.
I am presently thinking it might have something to do with the timing but I really do not know.
Thank you for you time,