I did a complete scope test on my MZ3 HB 2.3L with ATX last year and found this:
I did a scope test on the dyno at my shop with the old plugs as well as 2 new sets of plugs gapped at .051 and a tight .046. On the old plugs at rpms above 3,000 I noticed the spark was being blown out. Here is why:
Plug gap on the factory standard plugs.
.065
.060
.060
.073
I installed NGK iridium plugs at .045 gap (had to regap the plugs) and found under a dyno load testing with a emission and scope analyser, emission output was much better with a narrower gap than stock. Spark was scoped on a computerized analyser and the spark was jerky even when I had the factory .051 gap. A narrower gap did much better, which the power was nice and even throughout the dyno pull.
The reason for the narrower gap I chose is because the factory spec gap showed spark to not be as strong as I prefer at a higher rpm. You want a spark that has a good flame, but not too large so it blows out. Although a C.O.P. configuration is used on both Mazda engines, having a wider gap still can be bad where emissions and good fuel mileage is concerned. Before the change, I was seeing an average in the city of 17. After the change, I saw a 5 mpg increase. Mileage on the highway is also better.
I did a scope test on the dyno at my shop with the old plugs as well as 2 new sets of plugs gapped at .051 and a tight .046. On the old plugs at rpms above 3,000 I noticed the spark was being blown out. Here is why:
Plug gap on the factory standard plugs.
.065
.060
.060
.073
I installed NGK iridium plugs at .045 gap (had to regap the plugs) and found under a dyno load testing with a emission and scope analyser, emission output was much better with a narrower gap than stock. Spark was scoped on a computerized analyser and the spark was jerky even when I had the factory .051 gap. A narrower gap did much better, which the power was nice and even throughout the dyno pull.
The reason for the narrower gap I chose is because the factory spec gap showed spark to not be as strong as I prefer at a higher rpm. You want a spark that has a good flame, but not too large so it blows out. Although a C.O.P. configuration is used on both Mazda engines, having a wider gap still can be bad where emissions and good fuel mileage is concerned. Before the change, I was seeing an average in the city of 17. After the change, I saw a 5 mpg increase. Mileage on the highway is also better.
