I've been noticing that my car seems to "miss" a little, although I still have a great deal of power, but unfortunately not a VAG-COM to log the misses. So, I decided to buy the NGK Iridium plugs and check it all out.

It was very straight forward pulling the coil packs and plugs. I checked all of the Iridium plugs and each one was perfectly gapped at .28mm. I labeled and pulled each of the factory plugs and the gap ranged from .28mm to .32mm and the tips varied from bright white to a dark brown. I think the discoloration may have come from octane booster that I used in the past. I think that I'll pass on that stuff from now on. There is quality 105 octane racing fuel very close to my work for those times I need a boost.

The coil packs all looked very good and you could see shining gold on the contacts that looked practically new. Like was suggested on Fortitude, I used a little anti-seize on the plug threads, torqued them down to 18lbs, and used dielectric grease on the tips. When everything was reassembled, the engine just purred and I haven't noticed any of the "misses" experienced before.

There's my plug for the plug.

Cheers!

 

Well, I thought that after 400 miles I'd give everyone an update. My "misfires" are gone and the car is purring like a happy kitty. It's tough to tell if I have more HP like they say, but it has definitely made the car run nice and smooth. I've run about 300 miles on the 91 program, and now around 100 miles on the 93 program, and both are very strong. Worth the $8-$10 a plug in my opinion if they last at least half as long as they state, which is 80k miles.

Cheers!

 

Good stuff, Chef, thanks for the post and updates. I've been experiencing erratic misfires on cylinder 2 last year, bad enough to cause a CEL on cold starts. Service rep suggested it was bad gas (I hadn't eaten anything to warrant that recently)... I changed gas, and it was fine for about 8 months, until this past weekend when the CEL popped up again and stayed on for a couple of days.

I'll give the Iridium plugs a shot, sounds like they're worth a shot.

 

Interesting. With 91 and 93 are you referring to the RON of the petrol over there? Forgive my ignorance.

I once tried some iridium plugs in my 1.8T and as you say it's a good idea to take the power claims with a pinch of salt. I certainly didn't notice any difference. The benefit I suppose is knowing that you're using a 'quality' product. It's just another box you can tick I suppose.

 

The octane rating used in the US is slightly different than the UK. The US uses (RON+MON/2) which will give you a lower number than RON, but have the same detonation resistence. Our cars in the US spec a minimum of 91 (R+M/2) with ideal being 95. Tuners here typically use a base program of 91 and options for 93 & 100 programs, although the higher octane gas is a little harder to come by.

Hope this helps.

Cheers!

 

Sorry, this is a little bit off topic.

So over here standard unleaded is 95 RON and a drop of the good (eg Shell V-Power) is 99 RON. How does this compare? I always use V-Power and I've always had my remaps set up for it too. Bluefin is 98 RON by default.

 

In California, standard unleaded is 87 (R+M)/2, and premium is 91. Some states have premium as high as 93, thus the different programs. Our car's computer will adapt the timing from an ideal of 95 to the minimum ideal of 91, down to 87 with a reduction in power if need be. I'm not quite sure what the correlation between the two numbers is without research. Maybe a smarterchap will come out with the numbers?

Everyone here basically runs their car on 91, and adds racing fuel, or an octane booster for the bigger programs. I personally won't ever use the octane booster again, but the racing gas is sweeeeeeet!

Cheers!

 

95 RON in Europe translates to an (R+M)/2 of 90-91 US - which is considered lowest level of premium, here. North American regular is about 91-92 RON in Europe.

 

That all sounds about right. I knew that the octane levels were a little higher in Europe.

 

I just changed my plugs today after experiencing misfires in 4th and 5th gear around 5k -6k RPM. I'm happy to say I immediatly noticed a lot smoother acceleration AND my misfires are gone (did several 0-90mph runs full throttle). I bought my plugs from sparkplugs.com for about $7.50 each. They're located in soCAL so you can get them next day if you pay for ground shipping.