Last year, I decided to transform my low mileage, pampered sunny day, stock Miata into my new track day bitch. I decided to do everything at once (just like they tell you not to do): suspension, chassis upgrades, roll bar, brakes, tires, exhaust, etc.
In the course of installing gauges, I found that my Raptor shift light refused to work properly. This surprised me, as I had removed it from my old Miata (where it worked fine) and installed it exactly the same way into the other car. Both cars are '96's. The light's self test worked as it should, so I knew I had good power and ground. The problem seemed to be with the tach signal, although my factory tach is working fine. I sent the light back to Raptor to have it tested and they said it worked fine. I believe them.
To make a long story a little shorter, I bought a Porsche, hurt my shoulder and then pushed the Miata into the corner of my garage where it sat until this weekend. I made another attempt to install the light with no luck. I gave up on that, dusted off the car and went for a ride.
It idles fine and runs good at high rpm, but I noticed a bad misfire between about 1700 and 2000 rpm. I figured that it was probably old gas, so I went and filled it up and then took a few runs up and down the highway. Still the same problem. I'm starting to suspect that I am having an ignition issue that is not only making the car run poorly, but also confusing the shiftlight.
I made sure that the plug wires were making good contact, but that made no difference. The plugs and NGK wires have only about 10k miles on them, but they're also ten years old.
I plan to check the resistance of the wires, if I can find a spec for them, change the plugs, and check the timing. I thought I might have jumped the timing, but the car idles smoothly and runs great at high rpm, so I'm not sure.
I'll probably hook up the shiftlight and set it up for a three cylinder to see if it works, before doing anything else.
Any other suggestions that I should look into?
