Spark Plug Analysis Needed (Pictures)
 

Well, here is the story. I bought my car used about a 2 months ago. It is a 2005 with 21,000 miles on it. Right after I bought it, I got the big emission recall done because the previous owner had seriously neglected the car and not had it done. When the dealership did the recall, they said the plugs did not need to be changed, even though I complained about a "pinging/knocking" sound when accelerating.

I finally got tired of the knocking sound and decided to go ahead and buy some new plugs at my own expense, and got my usual local mechanic to replace them this morning. Sure enough, the car seems to run better and on the ride home, I didn't here the knocking sound.

I don't know jack about spark plugs, but to me the old ones look pretty bad. My mechanic also said that 2 of the plugs weren't even tight when he went to take them out, which makes me think that the dealer removed them to inspect them and didn't tighten them back up when putting them back in. From what I have read on other threads these things come from the factory crazy tight. I wan't some opinions from people that know what they are looking at before I go and raise hell at the Mazda dealership.

A couple more pics.

Those look "normal". They are the old-style plug which were replaced with a different design in the middle of '05.

I suffer from loose plugs frequently. They simply back themselves out, so it may not have been the dealer's doing.
Typically, they wouldn't have even bothered to check your plugs if they were intent on not replacing them.

I just cleaned my plugs and they looked exactly like those...you're fine.

Spark plugs look OK, but you will need to replace your spark plug leads.

Looking at the first picture, they all look pretty good. What you should be looking for is the color of the center insulator (see pic). If the center insulator (red area on pic) is a brown or tan color, the plugs like the A/F mixture you're feeding the engine. You can generally ignore the other crap on the plugs except to get an indication of what the carbon buildup elsewhere in the engine might be.

You can't clean Iridium plugs. If you cleaned them... you ruined them.

and the very crappy pictures (next time take a picture of the end so that you actually see into the plug) the plugs look normal other than you had some arcing at one of spark plug boots. This indicates loose spark plug cables more than anything else.

I tried several times to get a good close up of the ends but my camera wouldn't focus clearly on anything that close-up so I got as many angles as I could. At least I actually took the time to post pictures instead of just describing them.

That one plug was the only one that had signs of arching so I am thinking that may have been my problem all along. After driving the car more this afternoon, it is definently running better, with no more knocking sound.

I think your dealer shitting you, those are like the very original *old style* plug. if they really check you should've got the newer style plug for the Engine no Start TSB - something that every 8 should have.

yeah yeah they probably giving you BS like *your car is fine dont need to change it* , my ass.

The plugs look fine to me. but I wouldnt really clean them, I think I can afford 80 bux for every 25000 miles (yeah you're @ 21K miles, but close)

Raise the hell at them, you can probably get some of your plugs money back if you do (or they will just give you some plugs for free) Take a picture of your battery, to see if they did the Engine no start TSB.

the trailing plugs (left 2 in the 1st pic) are the non updated plugs, the leadings (right plugs 1st pic) are the updated plugs. the X cut in the plugs is the update, so fuel can drain out of them.

those plugs look pretty normal for rx8 plugs, in piston terms they usually look like some archeological find :)

Hmmm... now I am really confused. My new ones that I just put in looked the same as these. 2 had the "X" design and 2 did not. I ordered them from Trussville Mazda last week.

Trailing plugs dont have the X pattern. Only leading plugs does.

j9fd3s is right.

You can get the same plugs for 80 bux. btw. Im not trying to take trussville Mazda business away ..... but when you buy plugs next time, you should go places like sparkplugs.com or amazon.com

Did the shop who changed your plugs put anti-seize on the threads ?

lol, maybe they didnt update the trailings? its been a while since i looked at one. ive got a pile of the leadings from the recall though...

:iamwithst except that I'll add "normal for a factory stock RX-8"

here's the last set that came out of my engine

https://www.rx8club.com/attachment.p...1&d=1179031810

I was just happy not to have to pay the $170 :Eyecrazy: that my local Mazda dealership wanted for them. I wasn't really sure what I was shopping for, so I wanted to get them from a dealer this time. Next time I will go bargain hunting.

bahjesus those are clean :)

as for the plugs, the trailings look great, the leadings look a little worn, you can tell because the normally sharp edges on the ground electrode are getting smaller and more rounded off.

The greenish corrosion is indication that your boot may have been partially or completely off the plug. I suggest new plug wires becuase the green corrosion is also going to be on the inside of the boot.

PS, you can clean iridium plugs. I put them in a 600 degree Celsius oven for 5 minutes and it toasted off the unburnt organic residue. Then hit it with some aqua regia.

the upside: perfectly clean plugs

The downside: it completely cleaned the anticorrosion coating off the plugs :) After that they rusted in a day.

Lol, they didn't have any of that at Walgreen's. Closest I could come was a toaster oven and Aqua Velva. :uhh: :lol2:

Thanks for all the opinions. Whether they look like they needed it or not, I think it was money well spent because the car is running SOOOO much better than it was. I finally got the chance to get out on some back roads today and go through the rev's and it is running smoother and stronger than it ever has, even with it being in the mid 90's here today.

And the best part is that that horrible knocking sound is gone. :)

Not to thread jack but a question for the pros in here...

I just replaced my plugs today and needless to say these plugs are NOT cheap. Why cant we use a plug for another car and just set it to the correct gapping that the rotary specifies? I honestly dont know what the difference between all the spark plugs between different cars actually is because they all LOOK the same. Is the only thing different really just the gapping?

I use RX-7 plugs. http://www.mazdamaniac.com/portal/smiles/icon_shrug.gif

Just installed a set of FD plugs in mine. Just replaced the OEM ones at 32k miles.

http://i18.photobucket.com/albums/b1...s/P1030592.jpg
http://i18.photobucket.com/albums/b1...s/P1030596.jpg
http://i18.photobucket.com/albums/b1...s/P1030597.jpg
http://i18.photobucket.com/albums/b1...s/P1030598.jpg

But you're turbocharged :)

That doesn't matter, particularly.

lol, everybody knows running premix is bad now ... :hahano: :sarcasm:

Does anyone know the answer to my question I posted a few post back? What is the difference between the plugs between cars? is it the gapping or what?

gapping, heat ranges and longevity.

Generally, if you stick plugs that are too cold in a stock engine they just reduce the usable life of the plugs by a little bit.

the rx8 plugs are made for longevity and an even burn with the fine wire rare earth metals.

the downside of using lesser plugs is that you would have to keep an eye on them more frequently.

Plugs from other engines also have differant reach lengths, differant thread seats, and differant amount of insulator exposed. You need to get the spark in the right place in the combustion chamber too. And you don't want the spark plug to contact anything that is moving.

any comments on my plugs that I just pulled?

Ah ok, thanks guys!:icon_tup:

Not much that can be said other than use some anti-sieze next time. The thing that matters is the condition of the center insulator -- all your pics are of the outside shell, which doesn't say much about the condition of the plug...

The gap is wrong on RX-7 plugs.

The RX-7 gap is about .032 while the Reni gap is .050

You are probably costing yourself 10-15 HP

It is an entirely different style of plug.
The "gap" on the OEM plug is .049.
On the REW plug, there is no ground electrode, but 4 ground "blocks" that are also .049 from the center electrode.

my 0.02 is :

I hope you put Anti-Seize. is that rust on ur old plugs ?

cant really tell between good and bad from the picture, need to see the center of it. and I think your picture is too bright, take the picture with direct sun light behind you. That will give you some best picture.

Hmmm okay.

Since I sell plugs for the FC and FD in my webstore and gee I can measure the gap right now...

Whoops brand new 4 electrode plugs... gap at ...


.032

Try again. I have used and both the newer reni style plugs (NGK RE7CL and RE9BT), conventional NGK multiground RE plugs (BUR7EQP, BUR9EQP, BUR11EQP) and iridum (NGK IRL01-27 and 31) plugs in rotary 13BT, 13BRE and 13BREW engines for quite a while.

But I am sure using the older NGK multi-ground plugs are just fine in a Reni... they will last forever... just your gap is so small you are costing yourself both HP and gas mileage.

BTW, just for your info the factory spec for the BUR7EQ is .032 gap as well, so unless you have figured a way to re-gap a multi-electrode plug, you are using too small of a gap using that plug.

http://www.sparkplugs.com/productIma...1290%2D2%2Ejpg
BUR7EQ and EQP

actually my choice for plugs for a 13BT/RE/REW is the NGK RE7CL:
http://www.sparkplugs.com/productImages/1/re7cl%2Ejpg
Of course when using it with an older ignition set up as found on a FC or FD, you'll want to drop the gap back to about .038 when using a CDI system or .034 when not, for peak HP. But at $20 each (retail), they are by far the best price for a full Iridium plug used in automotive applications