banflu

Hi everyone,

4 years ago I was on here complaining of knock on my S2000 (has some Mugen mods as per signature). It is now very clear that this was due to the low octane fuel available locally - my car being JDM (higher compression ratio) and the Mugen ECU needs high octane fuel to function properly without knocking. I now found a solution for increasing octane and the knocking is virtually gone completely.

Anyway, back then some members had asked about the condition of my spark plugs.. and I had showed them these pictures (this is from March 2010 - stock platinum plugs):









Back then, some members had suggested to switch to new plugs - one step colder - NGK BKR8EIX. I think this made sense due to my knock problems and my car's modifications. So I bought a set of these and installed them.
Yesterday I decided to pull them out to check their condition after 4 years and 15,000 kms... this is what I found:















I am definitely no expert on reading spark plugs... but I see a lot of carbon deposits on these and I don't think it's normal. It leads me to suspect that maybe I don't really need to go one step colder.
However I might be completely wrong. So, any help would be appreciated regarding the condition of these plugs and whether I should change anything.

For what it's worth, I now cleaned them with a soft brass brush and re-installed them. Some carbon deposits are still there, though.

Thanks in advance.

Patrick

zeroptzero

I was going to suggest using a magnifying glass to inspect the deposits, if they look like silver/metallic ball-shaped deposits that is from detonation - molten metal splatter. I think it looks like some metallic splatter from the pictures but you need to look at it close up.

I don't think going one step colder would have hurt anything. The colour of the first plugs is mostly from fuel additives, those plugs looked okay. The newer plugs look like they are running leaner than the older plugs with the whitish deposits ?. Have you made any changes that would have leaned out the air-fuel mixture ? I'd still be concerned about detonation and the appearance of the deposits.

banflu

Hi, thanks for your reply.

I had pulled the first set of plugs about a week after I got the car.
The previous owner had said that he used to use NOS racing octane booster. I am assuming it contains MMT and I'm assuming this is what caused the reddish/brownish tint to the first set of plugs.

For the last couple of years I've been using a mixture of toluene with gas, and I've also been adding some ATF into the mixture as a lubricating fluid.
Now I have just stopped using ATF and instead started to use 2-cycle oil (TCW3) as this was designed to burn with fuel, and to lubricate upper cylinder parts. However I have now reduced to dosage because from research I've been doing it seems I was using too much. Also, this TCW3 I'm using says it was specifically designed to reduce or eliminate spark plug fouling... which is what I think I am experiencing.

Now seeing these deposits on the plugs I am suspecting that they may have been caused by the ATF burning inside the combustion chamber, and leaving deposits behind.
I think it's important to note that the engine was/is working perfectly fine; I just had a free weekend and thought to pull the plugs to see how they're doing.

I will use it for another 2000 km or so and remove them once again, to see whether the new fuel mixture of a low dosage of 2-cycle oil (instead of a high dosage of ATF) changes things.

Thoughts?

zeroptzero

Oh yeah octane additives will cause the darker colours of the older plugs.

Now that you provided that information the deposits on the plugs are ash deposits caused by the process of burning oil in the chamber.

On the next inspection check for silvery balls clinging to the insulator (under a magnifying glass and bright light) just to be sure you aren't getting detonation.

Slowcrash_101

I thought ash deposits were from burning crappy gasoline.

redlineracing

A dry,clean tan/grey color would be normal.

An "8" plug may be too cold......go down to a 7 OR 6 and see the results.

BTW...I run NGK BKR6E Gap .40 in my DD '03 w/102k miles.Does not burn oil.

\rlr
carolina

zeroptzero

Ash is present in most motor oils, when it burns in the combustion process it creates deposits like those in the pictures. Manufacturers are moving towards low SAPS oils to reduce deposits and negative effects on pollution control equipment. The fact that the OP was actually feeding oil into the combustion chamber would make the deposits much worse than normal.

s2000Junky

I see oil burning on your plugs, and running too lean. This is black wet looking crap on the outer of your plug and on your plug threads and base, and the white crusty crap on the electrode. When you add oil to your fuel, it displaces the fuel so you run leaner. In closed loop its not an issue because your computer will see the lean condition via 02 sensor and will add the necessary fuel, but at the last 2/3rd of your throttle % and WOT there is no computer intervention and you run leaner, couple that with your Mugen ECU which typically run leaner then stock to find more power along with a higher timing advance which wants more fuel, and your compounding the issue. I don’t know who told you to run ATF (never heard of this) or Two cycle oil in your car, but it was poor advice. Standard crank case oil getting into your combustion chamber will increase detonation tendency, and would be inclined to think ATF would as well. 2 cycle oil has a totally different formulation, so probably no harm there, however it will still displace the fuel you need as mentioned.

You can keep the colder plugs your using, but I would replace these with new and stop with the 2 cycle oil. Your just going to dirty up the internals of your engine and sensors causing more long term issues then good. Running a calculated amount of denatured alcohol is an effective and relatively safe way to go for upping your fuel OCT.

banflu

Thanks for your concise & helpful post.
Indeed, the Mugen ECU ignores the O2 sensors so if I was leaning out the mixture with the ATF it was not being compensated for.
I will get some new plugs - the same kind as I'm currently using (BKR8EIX) - however I'm not sure about stopping the use of TCW3 2 cycle oil.
From research I've made, the best way to increase octane in NA engines is by using toluene or xylene. These two hydrocarbons have a much higher octane rating than ethanol. However in most "homebrew" recipes, an additional lubricant is always recommended - especially at higher ratios.
Now I do agree that I may have been using too high a dose. Which is why I now halved the dosage to roughly 1:600 (1 part TCW3, 600 parts gas mixed with toluene/xylene at around 80%, 20%).
I've been making more research on this and I have found someone who actually recommends using TCW3 at this ratio even in normal fuel (without added toluene).. he found out that using TCW3 at this (small) ratio keep the engine internals cleaner, and according to him, makes for slightly better fuel economy. Check here: http://www.ls1.com/forums/f48/been-testing-oil-91206/


Obviously I cannot vouch for him but the guy looks like he knows his stuff...


Now let me go get those plugs..

iDomN8U

Sorry for the troll post.. But why are you doing this?

I would run within the conditions your in... Crappy low octane gas? Ditch the ecu and run stock ecu.

I see catastrophe going down the path your on.

A cooler plug should help with pre-detention but it won't produce miracles. (They are in better shape then the top plugs)

Your also following the recommendations on what works for him, which doesn't mean it will work for you. Without the proper equipment to test your conditions under a controlled environment, your rolling dice, risking the health of your motor.