SL1 cylinder 1 misfire

Some thoughts:

1. Make sure the plugs are still good, clean, and gapped properly (oil or carbon build up can foul them). Also make sure the injector is firing properly.

1. I've seen where the injector connector just needs to be removed and then sprayed with some electronics contact cleaner then re-attached. I've also seen where an injector can become clogged and not spray the proper fuel pattern. A good fuel additive, like Techron, might be a cheap fix.

2. Make sure your wires are good. The insulation can break down over time and not be noticeable but can cause arcing between wires or from the wire to the engine and result in misfires.

1. I've seen where the coil tower pack can corrode and cause occasional misses. You can easily remove the plug wires and then remove the assembly to clean it thoroughly with a wire brush, etc. Remember to mark which wires go where and route them exactly as they were originally.

2. Since you are having trouble with the misfire at higher speed, I'd also not rule out that it could be a fuel delivery problem. When was the fuel filter last changed? Could the fuel pump be starting to die and not delivering enough pressure?

1. When was the air filter last changed? Although a long shot, a severely clogged air filter might cause the problems at higher speed you are seeing as well.

2. Although not likely your problem, make sure the throttle body is cleaned occasionally. This usually manifests itself at idle not at high speed.

Good luck

Bob

I agree with Bob's suggestions. I recently acquired a 97 SL1 which I am trying to sell. It had the "Service Engine Soon" light on. Autozone read the code, misfire on cylinder 1. Plugs were totally burned out. I put in a new set of plugs, light went out, but I was still getting some stumbling. Cleaned the ignition wire connections which were very dirty, still no improvement. I lightly misted the wires at night to see if there was any arcing, there was not. Then, on a lark I swapped in a known good set of wires (from my 95 SW1) and what a world of difference. Smooth as can be. I'll add that normally I would have ohm'ed out the wires but some idiot must have hid my volt/ohm meter.

-David