Spark plugs and dealership question...

Evolved

Member
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2006 Mazdaspeed 6 GT
So, I'm wanting to get the spark plugs changed in my Speed6. When I got the pre-purchase inspection I was told that there was some carbon buildup on the OE plugs. From reading on here I'd like to go with Denso ITV22's since they are pre-gapped, one step colder and iridium tipped (better for turbo cars). When I mentioned this to the dealer he said that he's seen a lot of problems with Denso's and knock and would prefer to use NGK's. Is there any basis to that? Should I just let him use NGK's?

I'm stock, by the way, but intend on putting an intake on in the near future...if it makes any difference.

Thanks!
 
Well, the stock plugs are NGKs, so he may have been referring to that. Most of the guys running the Densos (including myself) are happy with the performance with them.

If you were looking at the NGKs that are one step colder, they come pre-gapped at .044, which is too large of a gap to adjust with an iridium plug. The tolerances for adjusting gap are only .008 each way. The ITV22's do come pre-gapped at somewhere between .029-.031 from what I've seen.
 
^^Thanks for the input. I noticed in shopping around that the ITV22's are about the only good plugs out there that are pre-gapped for our cars. I think I'm going to purchase a set of those and have the dealer put them in.
 
^^Thanks for the input. I noticed in shopping around that the ITV22's are about the only good plugs out there that are pre-gapped for our cars. I think I'm going to purchase a set of those and have the dealer put them in.

I would just do them yourself. Extremely easy to do. Remove TMIC, unbolt coilpacks, and remove plugs, then do the opposite and you're set.
 
I would just do them yourself. Extremely easy to do. Remove TMIC, unbolt coilpacks, and remove plugs, then do the opposite and you're set.

What tools are required? Is it really that simple? I just got the car so I don't want to screw it up or bring it to the dealer down the road and have them seizure because I did work on the car myself....
 
What tools are required? Is it really that simple? I just got the car so I don't want to screw it up or bring it to the dealer down the road and have them seizure because I did work on the car myself....

Yes, it really is. You'll need a 10mm socket, flat screwdriver, spark plug socket with 9" extension, and some dielectric grease.

Removing the intercooler is straightforward. Take two bolts out for shroud, then 3 bolts holding it on, along with the two hose clamps which need to be loosened, then remove the TMIC. Coil packs are 1 or 2 bolts each, pull connector off, and lay aside, then you're set.
 
You forgot an 8mm socket for the coil packs.

You'll love the Densos, I just put some in mine and it feels peppier.
 
Evolved, I'm off from work through the weekend. I can help you out with this if you want. It's pretty easy, but hell, meeting another MS6 in St. Louis is fine by me.

Send me a PM if you're up for it. I'm in the Kirkwood area.

I'll be installing my H&R Springs late this afternoon/early evening. I've PM'd you my info.
 
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What tools are required? Is it really that simple? I just got the car so I don't want to screw it up or bring it to the dealer down the road and have them seizure because I did work on the car myself....

Get a piece of 3/8" rubber hose.. like fuel line.. you can get a foot for less than $1.50 at any auto parts store. wait for the engine to be cool before you start. stick the plug in the hose and then thread in the new plug with the hose. You don't want to cross-thread it into the head. If the plug starts to thread wrong the rubber hose will just slip and it won't do any damage. Back it out then just thread it again. You can save yourself a possible major headache doing it this way. I use the hose, gap tool, anti-seeze on the threads (make sure to get none near the tip though), 3/8" ratchet, 9" extension, spark plug socket, some dielectric grease, and make sure the old crush washer is still attached and make sure the new plugs all have theirs before installing. You can also use the hose to dig out the old plug from the hole.
 

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