hhughes1

Time will tell but I used this and some vendor recommendations for my decision. These are spec'ed for the car.

An unaltered engine will run within the optimum operating range straight from the manufacturer, but if you make modifications such as a turbo, supercharger, increase compression, timing changes, use of alternate fuels, or sustained use of nitrous oxide, these can alter the plug tip temperature and may necessitate a colder plug. A rule of thumb is, one heat range colder per modification or one heat range colder for every 75–100hp you increase. In identical spark plug types, the difference from one full heat range to the next is the ability to remove 70°C to 100°C from the combustion chamber.

BerBer63

Can someone describe the issue with those plugs just for my education? Thanks and glad it worked out hughes

Sincity

Doesn't that mean that whomever has a tune should get plugs one range cooler? Glad you got it sorted out with costing that arm.

NORTH 44 C63

I was thinking about the possibility of using SLS plugs in the C63. Looking at the NGK website it appears the SLS runs a cooler plug (8 vs 7) so your reasoning makes complete sense.

j bro

very interesting and very annoying dealer could not figure out something as simple as that!

Glad u got it sorted out

hhughes1

Thanks, I think the word here is would not. It was actually the shop foreman hovering over the car to make sure that anything done would be billed. My SA was in CYA mode (he quit while my car was there) and no one was thinking like a mechanic just blaming the headers for what the STAR was showing. Feels better resolving it yourself anyway. Got two weeks of a free loaner as well.

GermanCars

One needs to be aware of problems that can be caused by different types of fuel. The problem of spark plug glazing can be real with leaded racing gas and/or additives as well as too hot a heat range. The ceramic ends up with a coating that alters the heat range of the plug. Misfires can result. The problem was worse before fuel injection, when overly rich/lean fuel mixtures added to the mix. It used to be a REAL big problem back before exotic metal plugs like platinum, iridium, etc. which can broaden a plugs ability to reject heat and still not foul at idle and low load conditions. Not to mention high voltage ignition systems. The term "Italian tune up" is just heating up the plugs to burn off residue, not applicable these days of feed back (oxygen sensor) fuel systems and computer controlled ignition systems.
However, if something goes awry such as a sensor failure, batch of bad or additive laden fuel, glazing and other deposits can occur and misfires will result.
Congrats on figuring it out!



.

grane

For the NGK range, an 8 heat range plug is colder than a 7.

For Bosch, a 7 heat rang plug is colder than an 8.

I am led to believe a 7 HR Bosch and 7 HR NGK are more or less comparable as to heat range, all other design features being equal.

jspAMG

You ca't blame the dealer too much. They aren't race mechanics. They are trained to make the car work as designed. They do not always have too much performance experience, if any. They have the parts available to them and nothing else.

Most importantly, if its a warranty issue, they aren't going to get paid for hours and hours of time to chase problems on a modified car.

Jim

j bro

hey hughes so i am getting an mhp tune by the end of the month, does that mean i might as well get some colder spark plugs to avoid any problems? as it could add as much as 95 bhp

GermanCars

My unsolicited opinion would be: depends on how you use your newly discovered power.
If you are staying on the street with short burst of full load you MAY want to go with one heat range cooler plug.
If you will track the car or spend extended periods of time at full throttle (absolutely nuts on the street!) you DEFINITELY should go to a cooler plug.
Have fun and be safe!

RNS-11Z

well i just ordered these plugs and k&n filters from that site. Thanks heaps hughes!!!! Also, those plugs are not for sale in Australia. Im currently experiencing a similar problem, but not as bad and only just slightly, since i changed my plugs recently with the factory spec. If i had seen this thread previously it would of saved me a few hundred $$$.

h.

hhughes1

Back with a 30 day follow up. Car has had zero issues and is actually running better than before thanks to having fresh plugs and the switch to an MHP tune. I will be at Roebling Road this weekend (provided Emily stays away) and again on August 20,21 so we'll see how lap times are affected. Was hoping to have a track specific tune on the new ECU that I bought but there are some issues relating to immobilizer coding for replacement (spare) ECU's that need to be worked out.

Regarding the original issue, after the plugs were replaced, the codes came back but the car ran much better. The front O2 sensor was replaced even though no specific O2 codes were being thrown and the problem went away completely. Should have started with Mthis' advice at the beginning but I think the issue was combination of several factors and may have began last year with the cam position issue being the first domino.

GHAZAN

Hey North,

How are those SLS plugs running? They are gapped a little differently than stock, not sure if it's a meaningful difference (.039 vs .044) Do you remember by chance how much they were each roughly?

RNS-11Z

I've had these plugs for 3 days now. The car is running amazing. I think the best ever and works awesome with the mhp tune.

GHAZAN

densos or SLS? what mileage do you guys recommend changing them at in general?

GMW

Hi all,
I just got the one stage cooler ngk sparkplugs should the gap be adjusted to .040?

Merc63

Where did you get these and what is the code?

GMW

I actually went on sparkplugs.com and ended up talking to a lady from Monarch Products Inc based in California. They didn't have Densos but after explaining my situation with the approx 77hp increase from my tune and what I read in the forums combined with my own experience, they recommended 1 stage cooler NGK sparkplug #6706 instead of the OEM #6043.

However they told me to have them regapped that's why I was asking on the forum otherwise I'll give them a call tomorrow.

GMW

Has anyone else fitted these NGK plugs? Per gap distance?

Merc63

According to this site: http://sparkplugs.com/results_app.as...1&AAIA=1443250

OE gap is 0.044"

GMW

Thanks!

ASHRAF C63

So I have been looking at spark plugs to replace my OEMs

what spark plugs are know to be the better performer out of the bunch?
I know life span should be a little shorter, but which ones should I go for

I also have Kleemann LTs and a tune and I beat on the car regularly

Edit, after some reading, I want to go with Brisk LGS, should I go for heat range 12? and what's the best place to get them from?

-AJ

Mort

Weistec used to recommend Brisk plugs one heat range colder but are now selling Bosch.

http://weistec.com/all/c/c-63/2012-2...m156-m159.html

ENV²

Are those Weistec plugs suitable for a p31 car with Eurocharged v5? I am getting the knocking/misfiring shakes in my car. Feels like plugs. Do you guys recommend the Weistec plugs or something better or more economical but cooler? I am going RoW boxes soon as well.