mike martinez

I have a turbo subaru motor in a sandcar with an older link unit. At 4700 rpm the motor begins to misfire. It sounds like it's hitting the rev limiter. The rev limiter is set at 6800 rpm. I set the programmer to the test rpm page then brought the motor up to 4700 rpm and noticed the readings started to jump around. With this info, the problem seems to be more ignition related rather than fuel. I have tried 3 different computers, a new coil, new spark plugs (gapped to .024"), new resitor spark plug wires, new timming belt, new cam sensor, checked all grounds, tried 3 different ignitors and I still get the same problem. It runs smooth up to this rpm level. It almost seems as if there is some sort of feed back or interfence signal that is corrupting the low voltage signals. Is it possibe the suppressor on the coil power supply might have gone bad causing voltage spikes? What else can I look at to determine were the problem might be? Thank, mike martinez