Idling rough? A little down on power? Slight loss of vacuum?

Check your plugs to see if they are screwed in!

I was going to switch to my "9" range leading plugs last night and when I went to remove them, they were floppy! At least one full turn out!
Now, I put those plugs in myself and I know that they were one 1/4 turn ratchet-tight from hand tight (about 12 ft/lbs) 8k miles ago.
Trailing were still tight.

Well, new plugs in and my idle vacuum shot up 3 kPa.

 

I changed mine a few days ago. I was expecting them to be in there tight, but they required almost no effort to unscrew. Is 12 lbs the recommended torque? I thought I recalled 20 or 22 somewhere.

 

Interesting that you are running 9's in the lead when months ago you blasted my opinion of running colder plugs in FI engines as another preventative measure against detonation. Why the change of heart?

 

Jeff,

are you running RX7 or RX8 plugs? I've heard some good things about the FD plugs and they are a hell of alot cheaper.

 

152 in/lbs or 12 ft/lbs.

Different plug design. I'd rather have the "7" range in the cross head plug, but "9" is what I have in my box.
Since I don't have detonation (and its 117°F and I can only get ethanol-ated 91 here, which sucks) I wouldn't be able to comment on the effect of the range change.
However, changing plug range is a last ditch effort if you do have detonation. It will only effect high RPMs, anyway.

They are FD plugs. Hence, my experiment!

 

Check them, don't count on the dealership doing it right. It's easy, and they get carbon deposits. Do the carb clean on them and use some coolant on the threads of the plug. 10 drops evenly. Reason I do that is, I had big trouble getting them out from dealership work. I thought I was gonna break #2 leading. I had to use both arms. One to hold it straight, and one to turn. There was a bunch of carbon build up, the last time I pulled them. ECU reset after that too. I sure hope my TB is clean.

Just use the coolant, and tighten down good. Without the coolant on there, you are unable to know if its all the way in. It just may get hard to turn. With coolant, they glide in until it hits bottom. Kinda like KY for cars. When its tight, your good.

 

I'm using what Scott recommended, NGK-5255 plugs. They are very cheap and seem to run well.

 

Actually, you should use real anti-seize.
It looks like silver crayon. Coolant will evaporate and leave the plugs loose.

 

Those are the Platinum trailing plugs for the FD. BUR9EQP. That is what I just installed.

 

while we're on ignition topic, do we have any favs for ignition wires? It's been 2 1/2 years with mine, and they do not feel very tight on the plugs.

I was admiring the Magnecor 10mm wires:
http://www.mazdatrix.com/8ignition.htm

I found a few topics from a while back, wondering if there's any changes since then.

 

I have the Racing Beat wires, but those magnecors are suppose to be good as well.

 

I made my own out of a Carroll silicone universal kit.

 

Question: Are you using FD trail plugs in trail also? I compared the two last week and confirmed that the FD trails are longer than RX8 trails which would be a concern for plug seating to the housing I would think. I actually tried the 8 plugs in an FC application and the results were not good. Good test though.

Agreed as a last ditch if you do have detonation. That would indicate tuning issues for sure. I like the colder range plugs as part of the whole package as they allow a "slightly" leaner mixture to be utilized while still on 93 pump gas.

No band aids here

 

Scott ships 5255 for both trailing and leading. He said there was no need for different sparks to be used.

 

I have the 8.5mm set of Magnecors installed, as of a couple of weeks ago. No problems.

They should last a long time being silicone covered wires, from what I have read.

 

No 93 here, so that wouldn't be an option.

The FD trailing plugs should be installed with a a set of shims.

 

Previous post say's different. Most people would not know to find a shim and install it.

Everything I've read say's different.

That one needs two different plugs.

What does the Mazda race team use on their Formula 1 or GT cars?

 

Who's previous posts? When using 5255 there is no need for anything besides what comes in the box.

 

The 2nd and 3rd gen plugs are all the same length regardless of lead and trail unlike the Rx8 which has a shorter lead plug. This would mean that using anything else in the lead hole on the 8 would require a shim of the right thickness for the plug to properly seal to the housing.
Or you can trust that what was designed for the engine will work best but cost more and not require trying to find indexing shims.
(if you really need them, try Pegasus Racing)

2 rotor stuff I am familiar with use NGK race plugs usually in 11.5 heat range and at a cost of around 35.00 each last time I bought some

 

Just went over 15,000 miles on my bone stock 8. When should I change the plugs? I know the stealership changes them at the 30K service.

BTW... speaking of recomended services. I know I'm due for one at 15K. Will I run into warranty issues if I do the work myself and try to save some cash? I know it sucks for resale because I can't prove that it was done. Anyone?

Thanks.

 

There's really not much to do at 15k.

I would do coolant, diff, transmission swaps at 30k (I had diff and transmission done twice by 30k though)

 

read the owner manual do what is req.... keep records of
what is put on the car.

beers

 

So do I need to change the plugs at 15K or no?

 

i would pull them and look at them....

i think they are good for about 20k...

the service life on them is 30k.

beers