Pasman

Wondering why a 1989 C4 specifies a different spark plug
than the rest of the 964's? NGK specifies a different plug for
the 1989 vs. other years. Curious why??

18T_BT

Must be a typo on their site is all. If you look up 1994 964 it lists a different plug for the same engine. The three prong Bosch is what was OEM. I think they selected it for longevity reasons and to help against misfires not performance, which is strange as it's a double plug engine anyway. Back then they also said to change them every 15K and later updated it to 30K. If your car isn't misfiring, don't change the plugs.


https://www.ecstuning.com/Porsche-19...ion/ES2718230/

https://www.ecstuning.com/Porsche-19...ion/ES2718232/

http://www.pelicanparts.com/catalog/..._pg1.htm#item3

Pasman

Thanks 18T, I changed the plugs to Bosch, since it was original OEM, but thought that the NGK website was strange for listing different plugs for the different years.
Hopefully see you driving around the DMV area.