Go48

Simple way to remember:
Leading =lower
Trailing=top

The grammer may not be correct, but so what.

HCS

I see that Sparkplugs.com has Denso plugs for the 8. Does anyone know if these are any better that the NGKs? Are they worth a price premium of 75%?

cliffkemp

Unless they can gap the plugs better than ngk, there is no benefit. Spark plugs just deliver the spark. The coils could make a difference if defective or burned. New vs new, there is no benefit unless the gap is off by either brand to the point where top end is affected. too wide a gap and takes more to make the jump, too short a gap and not much can go wrong really. .48 is stock but, if found to be larger, could hurt your coils in the long run cause will take more volts to make the jump and hence more heat to the coils on topend if above 5-6k depending on condition of the coil. Get all that?

HCS

Got it. Thanks

alz0rz

iTrader: (41)

Did this for the first time 2 weeks ago.

Took of the driver side wheel and had clear access to all 4 plugs... I didn't even have to go underneath the car. (1 jackstand)

Extension with a standard 13/16 spark plug socket got them all out easily. Took me 20 minutes to change all 4 spark plugs and wires this being my absolute first time.

EXTREMELY easy to do and learned a few things about my car in the process.

Only hand tool needed:

MiNoo511

When I bought my '06 8, the glove box had four spark plugs in it. Are those replacements for the stock ones? And I had those spark plugs for awhile now, over two years without installing it, would they still work fine?

Jedi54

iTrader: (7)

they might be the old version. got part #'s?
OR they could be from a completely different mazda that a tech or porter accidentally left in your car.

MiNoo511

I don't have the parts with me because I'm at work right now. When I get a chance, I'll go grab it and post the part numbers. Thanks

MiNoo511

Hey Jedi, the part numbers for the spark plugs are RE8B-T and RE7C-L and there are two of each kind. Are they for rx8s? Are they the old version?

mkztg

I wanted to say thanks for all the guidance this thread provided. I changed out my plugs, wires, and coils today. I'm not very mechanically inclined so it took me 2 hours but I got it done and had fun doing it. Only 25k miles on my 04 but it was running like crap so I decided the car needed this... Man was I right. She runs very smooth now! Thanks RX8Club!

BOB9995

MKZTG
The next time you need to replace your plugs, you might want to try these guys, they are cheaper than dealer prices. http://www.sparkplugs.com/results_ap...1&AAIA=1416844
and they have the NGK plug update that Mazda required, you no for the trailing, or was it for the leading plugs.

BOB9995

peterlemonjello

Just changed my plugs at almost 60k miles. This set had almost 18k miles on them.

HCS

Just wanted to drop a line and say thanks for the DIY. It helped a lot

tomdoerflein

I'm going to change my plugs next week and have noticed a couple of posts similar to the above here. Is it necessary to index the plugs? Do they need to be shimmed so the reachis correct? Or do I just drop them in and torque to the specs?

solito

Just recieved my plugs from Advanced Auto and wanted to verify that these are the current plugs for our car. I called Advanced Auto to confim this and they said it was correct. ...But, before I install these, I just need another confirmation from a forum member. These are the plugs sent:
The box says NGK Laser Iridium Premium(RE9B-T) and (RE7C-L)

Truly appreciate.

RX8-Frontier

yep. 7's in leading, 9s in trailing (that's also why the L and the T are there...)

solito

RX8 Frontier

gtommy

iTrader: (2)

After trying to clean and install some new plugs yesterday following the DIY, I noticed that the 2 trailing plugs (which need a wobble to be taken out) were going in the thread with an upper angle.

By that I mean that when I try to put the plug back in, the upper part of the plug is touching the end first, while there's a gap left at the bottom part of the spark.
It's somehow inclined tower to upper side.

I read that one person had the same kind of problem in this thread.

Any idea what could be done to solve that? What could be the consequence of having that?

It was the first time I removed the plugs myself, it was always done at Mazda before so I suspect they did that...

The 2 leadings sparks go in perfectly and firmly. Not the trailing ones.

AE92

iTrader: (1)

i have that same problem. i was attempting a cleaning. so i started with the front rotor leading plug, i tried to install it and it just stopped only after going half way in. so i backed it out and noticed its threading wrong. just like the guy before you. so im taking it to a machine shop tomorrow and hopefully they can re tap it. wost case is a helicoil. in order to do that, they'll have to remove the left engine mount. im just glad it still runs but im only going to run it to get to the shop. im scred that since the plug isnt all the way in, its not going to ge tth eproper cooling effect from the block itself and may crack. and i do hear wat sounds like a very minor compression leak or rhythmic gas leak from that area. i cant feel anything around the plug though. and the idle seems fine and it revs up . but thats just dumb so im taking it to the machine shop monday.

StealthTL

iTrader: (1)

Always use a dab of Never-Seize.

Always.

ALWAYS.

The steel will weld to the aluminum without it, always - I had my first rotary plug seize in 1976 and the need for anti-seize compound on the threads has been in the service manuals since back then.......


S

DOMINION

^Yup that stuff works great.

AE92

iTrader: (1)

so uhh any solutions on spark plugs goin in crooked yet?

gtommy

iTrader: (2)

I did apply anti-seize to the spark thread. I guess it will make the removal process much more easier...

But still, before I install the 2 new sparks and cleaned the other 2, they were misfiring a lot. Now they don't, but Im still having a big big lack of power. It takes forever in any gear to get to 9K. No push at all.

I'm going to change the other 2 sparks so I ll have 4 brand new sparks installed but with the inclined trailing plugs, I believe that this is where the problem is coming from.

So can it be fixed? I have no clue how... and Im blaming mazda for that.

Actually they installed 2 coils last month along with a plug wire. When I was changing my plugs, I noticed that the wire was loose (on the spark end). Conclusion : I simply don't trust mazda dealers anymore. Specially when they tell me that changing 4 sparks is an 1h30 job.

So now, what should I do to get the trailing thread fixed? (get rid of the inclined angle)

skrubol

iTrader: (1)

Which plugs are normally replaced as part of that big TSB? I remember them only replacing one set.

I just replaced 3 of my plugs and the coils. The rear trailing plug would not come out no matter what. I was able to back it off a few threads, very painfully, and then it just stuck. It must be totally cross threaded. I cracked a 1/2" plug socket with my impact wrench trying to get it off.
The other trailing plug hole had slightly damaged threads as well, but came out and went in without too much trouble.

AE92

iTrader: (1)

was this a problem from the dealer or did you guys cross thread it yourself? and "gtommy", were you driving this all this time around with your plug halfway in? or did you actually crank it down into the hole so it sealed?