I have a 2005 R53 with 85k km on it that I've owned for about six weeks. Right off the bat I installed new plugs (NGK Iridium) and wires (also NGK). As far as I thought, these plugs were pre-gapped. Now I've read a bit and have been lead to believe that's not totally true.

I'm replacing the coil pack this weekend, and will be removing the wires to clean the engine bay and check the plug torque. Should I check the gap as well? I don't have tools for this, so I'd need to make a special trip to buy some. I'd rather not remove the plugs and fork over the dough for gapping tools if I don't need to. Plus I'm not totally positive I have the skills/know-how to re-gap them if necessary. Is this something I should be overly concerned about? Thanks!

 

Iridium plugs have very brittle tips....
Gapping can make them break...
unlike platinum which is flexible...

 

I replace my factory installed plugs at 48K, she ran great before but now she is peppy as hell and runs like a champ! I didn't gap mine when I got them...

 

well I DO check the gap and I've found Iridiums to be properly gapped out of the box for both MINI and Hondas in the last year . . .

a spacer gauge can be had for a couple of dollars at any auto part store and technically you could set the gap with a decent pair of needle nose. A slightly better feeler - specifically for spark plugs usually has a 'gap setter' attached and is STILL not very expensive.



on sale at harbor freight for $2

fancier
$7 at AutoZone

you only need a tool to open the gap ... to close it ya just tap it on the table top a time or two! Or am I showing my age? On my first car I needed to clean and gap the plugs every oil change.

 

So it's that easy? I mean, how hard is it to bend that little tab the difference between .032" and .034"? I'm afraid of getting accidentally ham fisted on it or something...

 

http://www.ngk.com/faqmain.asp

 

And the answer is... No, they're not - not remotely. Of four plugs, mine varied from .026" to .038". This is after about 2k km's use; not sure if that changes anything, but I don't see why it should. I bought both round- and wire-type gapping gauges, and checked and rechecked them all. I also bought a nice new pair of Channel Lock NNs, and went to work...

I regapped them all to .045" - figuring this was a happy medium between the .032" I'd read about everywhere and the .06" Out Motoring suggests when employing an upgraded coil pack. (I installed an MSD at the same time - and yes, I'm now aware it's probably no more or less useful than the stock coil.) Well, whether because of the new coil (doubtful) or the consistently regapped plugs, she now PURRS like a kitten. I kind of wish I knew whether it burned cleaner, or more efficiently... It's certainly smoother feeling, especially at higher RPMs. I'm honestly considering pulling it all apart and opening up the gap just a little bit more, just to see if it gets even better!

 

if you changed everything at both ends, go the last step and change your wires too

spark plug wires do wear out

I learned this in my Miata days where I saw a recommendation to change wires every 30,000 miles. I was way over that and hadn't noticed any real change but went ahead and bought wires. WOW, what a change. I'm no electrical engineer but I believe it has something with increased resistance building up or developing over time.

So why leave a potential weak link in the system?

When I do an ignition tune on the 79 (with a tweeked 1275) it includes plugs, cap, rotor, coil and wires. Points and condensor were replaced by an electronic module last time around.

 

My Iridium plugs were gapped correctly out of the box. I know this because I checked. It's part of doing the job, and if you didn't check, you didn't do the job correctly. Don't think about the cost of the tool. Think about the savings over paying a pro, and the piece of mind knowing what's in there.

 

I wasn't worried about the cost of the $2.99 tool. (I bought one of each model, after all.) I a) was worried I couldn't adjust the gap properly if I needed to and b) believed the literature that said NGK Iridiums are properly gapped for your vehicle, etc.

And I changed the wires back when I changed the plugs, back when I bought the car. I just bought some NGKs that were on sale, along with the plugs, and were a pretty shade of blue.

 

Obviously some of us are reporting pre-gapping to be on target, and some are disputing. We don't really know what happens to the part from the time it leaves the mfg until it ends up in our hands. A counter person could take one out of the box, then drop it, and put it back. Or a customer could do the same, and return it. So even if mfg's QC is 100%, it can be off by the time we get it. I check everything. Well that's not completely true. For instance, I don't mic up brake rotors, and check for runout. There are some things that are easy to remove, and will show themselves as bad on first use. I've also never had a bad rotor out of the box. I do check spray patterns on injectors. I do measure resistance of new spark plug wires and coils. I was also professionally trained as a level II mechanic, and did spend a total of eight years in that field, but I still consider myself a shadetree. So maybe I'm a bit more particular than need be. Of course some of those years were spent in manufacturing, and I KNOW how even acceptable products can vary. At least in America.

 

I'm not blaming NGK - just reiterating the importance of checking the gap, now that I've learned how to do it myself... The last leg of my plugs' journey was most likely by Canada Post (to Canadian Tire...ugh), so there's no telling what ills could have befallen them in transit.