So Today I changed my spark plugs. I bought my 04 mt 8 with 59K on it. It now has 65K. From what I have read on here at 60K things like spark plugs, coils, and wires need to be changed. As i removed the first trailing plug I noticed it look wrong. Then I saw the L on the side. I continued on and noticed that both trailing plugs were really leading ones. My car had four leading plugs in it. The plugs seem pretty new too. Anyone have any thoughts on this?

 

lots of stupid out there.

good that you caught it..

beers

 

im checking my plugs tomorrow to see if it has the L or T stamping on it? Where would this stamping be? Any pics? Also, why does the same car have (2) different plugs?

 

it would have a L or T at the base of the poreclin(mispelled)......

 

Because one plug is the main ignition while the trailing plug just ignites "the rest".

 

The leading and trailing plugs on an Rx8 have different reaches - the distances the plug is able to screw into the block/housing. I believe the trailing plugs have a longer reach than the leading. Running (4) leading means your "trailing" plugs are probably further removed from the combustion chamber. If the plugs are in good condition, it probably makes a minimal difference - akin to a weaker spark. I would think that as they wear, the "trailing" plugs would develop issues first as the plug was already operating with a disadvantage but this is purely speculative. I run 4 trailing Rx7 plugs (2 shimmed) in my car without issue so I imagine the reverse wouldn't be a serious problem.

 

thanks. After all my reading I had not read where using 4 leading plugs where an advantage or a common practice. It seemed odd so i just threw out the experience to see what people had to say.

 

What heat range do you use? How long do they run well? What gap do you set too and how much does it open up during those miles? Do you have pics of them after a full cycle.