"I bought a sweet Mazda Miata a few weeks ago and now have a nice combination car."
- Thread starter Rupunzell
- Start date
Rupunzell
Bernice Loui
Curious that the ground electrode that failed in the Miata was also made by Bosch...
I'm not a fan of platinum plugs and Bosch plugs in general. For a time Denso plugs were preferred for the Fiat and stock NGK-R plugs for the SAAB.
When the ground electrode fails, the coil will try to compensate by significantly increasing the voltage required to jump that far over sized gap. This increases the internal stress on the HV insulation exponentially.. One small pin hole caused by the excessive HV on the winding insulations leads to rapid and destructive failure of the HV coil.
The real question is, what happened to the four ground electrodes that are no longer attached to the spark plug? Odds are there will be internal damage to the cylinder head and piston.. like this (screw head fell into a cylinder):
http://www.motoiq.com/magazine_arti...rankenmiata--failure-is-always-an-option.aspx
Cats don't last forever, they have a finite life. If the ignition fails, un burned fuel/air mixture dumped into the hot cat will melt the cellular structure inside the cat causing it to melt internally and fail.
Tomorrow, the cylinder head is coming off the Miata and I'll post more about the findings later.
BTW, SAAB owns the patent on the DI cassette which puts a coil on each cylinder along with the control electronics. This is why other car brands can only put the coil on each cylinder, not the entire package.
Bernice
I'm not a fan of platinum plugs and Bosch plugs in general. For a time Denso plugs were preferred for the Fiat and stock NGK-R plugs for the SAAB.
When the ground electrode fails, the coil will try to compensate by significantly increasing the voltage required to jump that far over sized gap. This increases the internal stress on the HV insulation exponentially.. One small pin hole caused by the excessive HV on the winding insulations leads to rapid and destructive failure of the HV coil.
The real question is, what happened to the four ground electrodes that are no longer attached to the spark plug? Odds are there will be internal damage to the cylinder head and piston.. like this (screw head fell into a cylinder):
http://www.motoiq.com/magazine_arti...rankenmiata--failure-is-always-an-option.aspx
Cats don't last forever, they have a finite life. If the ignition fails, un burned fuel/air mixture dumped into the hot cat will melt the cellular structure inside the cat causing it to melt internally and fail.
Tomorrow, the cylinder head is coming off the Miata and I'll post more about the findings later.
BTW, SAAB owns the patent on the DI cassette which puts a coil on each cylinder along with the control electronics. This is why other car brands can only put the coil on each cylinder, not the entire package.
Bernice
Rupunzell
Bernice Loui
Cylinder head off engine. The damage from that spark plug electrode needs to be seen to be believed.
The pistons look like they have been sand blasted and the cylinder head is now scrap aluminum.
More Miata weirdness discovered. What I will say, the Miata is a highly engineered car for it's intended market. Virtually no engineering/design stone un-turned for production viability and cost.
Need an new image hosting service to share the images.
Bernice
The pistons look like they have been sand blasted and the cylinder head is now scrap aluminum.
More Miata weirdness discovered. What I will say, the Miata is a highly engineered car for it's intended market. Virtually no engineering/design stone un-turned for production viability and cost.
Need an new image hosting service to share the images.
Bernice
usta in Portland
Daily Driver
Bernice, an opinion please.
I'm searching for a useable next generation classic and have run across the Lexus SC300 from the early 90s. Do you know anything about them?
I'm searching for a useable next generation classic and have run across the Lexus SC300 from the early 90s. Do you know anything about them?