DIY: Spark Plug change.......
 

Here's a little DIY on how to replace your own spark plugs. Some people have reported Mazda dealers charging $300 for this (:Eyecrazy: )! For anyone wondering why I changed them, they were extremely fouled from the first 10,000 miles of driving (before L and M).


*EDITED TO ADD- Remove the driver's side wheel before starting*

#1 - Jack the car using a good hydraulic jack, placing a piece of wood between the jack and your frame rail. This will prevent you from denting the underside of your car. ALWAYS PLACE A JACK STAND UNDER THE CAR. THIS COULD SAVE YOUR LIFE!

# 2 - From underneath the car, you have a clear reach at the rear plugs. I recommend breaking them loose with the wrench, but then removing them by hand. Not only do you avoid banging your knuckles on everything, but it goes faster.

Once removed, your plugs will look something like this. Clean them in your preferred method.

For the front rotor, the plugs are tough to reach. Next time, I will remove the driver's side wheel, but since I didn't have my lug key with me, I still reached them by turning the wheels all the way to the right. Behind the wheel, remove the upper fastener on the rubber splash "thingy". (Oooohh....Technical terms! :D ) This is NOT a screw, but one of those that only requires a quarter turn to release it, similar to the clips on your wheel well liner. Once it pops out, gently pop out the washer by sliding a flat head screwdriver under it and twisting gently. Did I say gently? Seriously people, these things beak easy.

If you've got skinny arms, you CAN use this method, but as I said: Take the wheel off.

3

The front plugs are now visible.

When reinstalling the plugs, be sure to apply a light coat of anti-seize to the threads.

Each plug is marked with a T or an L, which indicates leading or trailing. It is VERY important they are reinstalled correctly. Double check this, and note the T and L cast into the side of the motor beside each hole. Match these up.

Also, you did notice that the trailing plug wires are marked with green and blue tape, right? If not, make sure upon reinstallation that you attach them correctly.

That's it! I haven't even taken the car out yet to see if it helped, but at least I know how to do it now.

REMEMBER: SAFETY SAFETY SAFETY WHEN WORKING UNDER YOUR CAR!!

Nice DIY man. :D

Nice illustration ... job well done.

Sure it is dirty.

Is there any spark plug better than what we use? We use NGK Iridium right?

factory plug is the best. check out silverbullet.com for a write up on plug test on an Rx7. These factory plugs are really expensive so I guess cleaning is justified but I wouldn't reuse them too much. Plugs can crack under the high heat of a rotary engine if they become old.

I was not able to thoroughly clean the plugs.

I removed the carbon on the top surfaces, but without a sandlblaster, I couldn't get down to the bulk of the gunk that was deep inside.

It DID make a noticeable difference in throttle response and bottom end. The car pulls smoother, and the loss of power at 7K is gone. However.... The knock is still there. I think new plugs would do the trick, because it is lessened after the partial cleaning of the plugs. Mazda needs to step up and replace plugs on cars with several thousand miles on them before L was released. I doubt they will, though.

My plugs were replaced by the dealership under warranty at 12k miles, because I had a random misfire. Maybe you can get them to replace yours?

Few notes on this -

First off, VERY GOOD call on coating the threads of the spark plugs with anti-sieze. If you do this, when you go to remove the plugs later, you just break them loose then remove by hand. Don't do this, and you'll be there a half hour with a piece of pipe over the socket wrench, turning it a quarter turn at a time. Our convertible RX-7 had monkey-installed plugs, and I didn't think I was EVER going to get the #1 leading plug out.

For the time being, the RX-8's iridium plugs are the best thing going. The old copper or platinum NGK's the RX-7 used might be worth a try, but I think life would be a lot less, and I don't know if it would cause any driveability problems. They ARE a helluva lot cheaper, though - $5.99 for the coppers each, and about $8 or so each for the platinums.

On the plug wire markings - best case scenario, you do want the right wire going to the right plug. But, the leading plug wires, if the ignition fires like the RX-7 did, are swappable - leadings fire at the same time. Trailings don't, and swapping the trailing wires will result in detonation, which is hella bad on a rotary :). Long story short, it's a REAL good idea to make sure you've got the plug wires on right. The stock NGK wires are marked, but aftermarket wires might not be - probably would be worth marking them.

I have seen little spark plug cleaners before - it's a small doober you hook up to a compressed air source and it has sandblasting sand (or the like) in it. Screw in the spark plug, hook up air, squeeze the trigger, done. Dunno how well they work, or if they'd cause a problem with the iridium plugs (doubtful).

You'd be VERY suprised how many problems can be solved with a fresh set of plugs. I've seen people buy cars WAY cheap just because the plugs were fouled - the owner thought the motor was blown.

Does the '8 use different heat range plugs for leading and trailing? I'd reckon so.

Dale

Is swapping out the plugs and letting the engine sit for a bit with the holes open a reliable way to de-flood the car?

Not in particular. Best is to find some way of disabling spark and fuel - probably pulling the ECU fuse or the like, then cranking the engine over for a second or so to blow all the fuel vapor out.

You have to be REALLY careful with this, as atomized fuel is VERY flammable. You have to be certain the spark is disabled, as the disconnected spark plugs could ground to something and ignite the fuel in the air.

Dale

Where did the pics go? Yes I realize how old the write up is, anyone have a newer version?

Can you not reach the front rotor plugs from under the car like the back rotor?

Pictures have been missing on other "older threads". I believe it was due to some server problem. Contact a moderator and they may be able to restore them.

Yes, all the plugs can be reached from the bottom. No need to remove the wheel.

testing to see if adding another pic will fix the old ones....


Yep, that seemed to do the trick

Thanks Nubo! - for restoring the pics.
and Tony - for a great DIY post - I just finished copying that all to a single document...<g>

One thing, though... On my '99 Solara, Toyota called for double tipped NGK plugs that were gawd awful expensive (maintenance interval was 70K miles!) - I believe they were iridium as well - I seem to recall a note in the package about _not_ cleaning these b/c the plating on the electrodes could be damaged...
Anyone else have any background on this?

Do you have to use a special socket for these plugs, or are they just like any other plug?

When I did mine last week I used a regular 5/8” spark plug socket (pretty sure it was 5/8") Having at least a 12" ratchet extension helps also.

Thanks just wanted to make sure.

Improved Leading Plug
 

Just received my new plugs from sparkplugs.com and noticed the part # for the leading plug was different than what is called out in the workshop manual. It also has notches in the end that I hadn't noticed in any pictures before.
RE7A-L vs. RE7C-L

The following explains the difference (copied from sparkplugs.com)

NGK: Racing plug

14mm thread, 21mm reach, 20.6mm(13/16") hex, 62mm height, Trailing plug, solid terminal, notched shell aids cleaning, fine wire, (.08mm) iridium center electrode, fine wire platinum ground electrode .048" gap (1.2mm)

Original equipment, fine wire plug designed to give you optimum spark from your existing ignition system. Slightly recessed fine wire iridium center electrode requires less voltage to ionize(jump) the plug gap. This allows a stronger spark which will better ignite the air fuel mixture leading to more power. The iridium center and platinum ground electrodes for extreme durability. Fine wire platinum ground electrode to reduce quenching. This plug is improved over the RE7AL as the shell has been notched to reduce fouling and improve cold starting.

NGK Racing plug 6700 RE7CL $19.95

I'll be putting these in tomorrow morning. My car is a December, 2003 build date with 30K miles and has had several different flashes.