Spark plugs need replacing after 3,000 k :(

[method]

Got a bit of a problem, im hoping someone can tell me what it is from the colour of the plugs.

All i know is if they are black its running rich and if they are white your leaning out.

The plug is black but the top looks like its corroded a lot. A rusty colour with lighter flakes on it.

My car doesnt blow smoke to my knowlage so i dont think its running rich, or very rich at that. I bought some iridum plugs, biggest waste of money and after 3,000k's, not even 2 months my car is missing again.

It only misses under boost and sometimes its quite bad. Its either the plugs, the leads or the coil packs.

Thought id check the plugs first and they dont look too healthy. Was wondering if you guys could tell from the pictures.

Is there an easy way to tell if the leads are gone? I have some aftermarket leads. They look like they are good quality, quite thick and have a heat resistant brading and they are earthed.



Cheers

[Al]

Are all the plugs like that? Or just one or two?

[fivebob]

You can't really tell much from a plug that's just been removed from an engine, especially if it's been idling before they were removed. The only way to accurately read your plugs is to run the engine at the rpm/load level where you want to take a reading, then shut the engine down and coast to a stop before removing the plugs.

That said however, have you been running octane booster?

[method]

Will check all the plugs tomorrow.

Funny thing is i just took my car for a "drive" at 1am and it didnt seem to be missing at all. thru 1st 2nd and 3rd, repeated the test for accuracy.

Pictured is no1 plug, its the only one i removed. I quickly wiped it with a cloth and put it back in, checked all the leads at the coil and plug end.

Could it have been a loose lead? Funny thing is none seemed to be loose but i twisted them anyway to make sure they were seated. And the missing only happened under full boost, then all the way to redline.

Hmm, they would be a tad hot if i did that, if the problem comes up again i will chuck some replacements in, i will check them all tomorrow.
Is there a way i can safely "clean" them, they are iridum tiped so i will be careful.

Yes i used wynns octane booster once, around the start of the month, i was forced to feed my car 95 so i put in a bottle of octane booster and kept the rpm low, im paranoid about detonation even though a lot of people run such engines on premium,.

[Boldy]

According to this supra site

http://www.cygnusx1.net/supra/techtip/sparkplug.html

its looks like carbon fouling?

[fivebob]

According to this supra site

http://www.cygnusx1.net/supra/techtip/sparkplug.html

its looks like carbon fouling?

Err, how to reach that conclusion? You read the tip of the insulator, not the edge of the plug.

[fivebob]

Yes i used wynns octane booster once, around the start of the month, i was forced to feed my car 95 so i put in a bottle of octane booster and kept the rpm low, im paranoid about detonation even though a lot of people run such engines on premium,.

That's probably your problem, and the cause of the orange deposit on the top of the plug. Methylcyclopentadienyl Manganese Tricarbonyl (MMT) is well known for fouling spark plugs and it's best to avoid it. If you need octane booster use Toluene, not as convienient, but it won't cause problems if used correctly.

[method]

Thanks fivebob, I will carry some Toluene with me, how much should i use? Originaly thought i could carry a bottle of methanol and mix around 7% into my fuel next time giving me around 98 octane.. i think

[Al]

It should run alright on 95 shouldn't it? You have more intercooling than an mr2 does and my car had been running on 96 since it came into the country in 1997

[fivebob]

Toluene should be safe up to around 25%, though 10% should be more than enough and should result in approx 97 Octane. Toluene levels already in fuel can vary, but seeing as you're in Auckland you should get a fairly consistent result, as the base stock has tighter tolerances than the rest of the country. That said however, results of adding toluene wouldn't vary by more than 0.25 at that level.

Don't use methanol, as that opens up a whole raft of possible problems like crosion of fuel rails and moisture entrapment. Even ethanol poses problems if there is any water in the fuel, it can all drop out of suspension and collect in the fuel pickup area. Often resulting in a stalled engine, as it gets a dose of 100% ethanol & water mix

[fivebob]

It should run alright on 95 shouldn't it? You have more intercooling than an mr2 does and my car had been running on 96 since it came into the country in 1997

Maybe, but it's a personal preference thing, I'd prefer to run 98 all the time, but would run 95 in my gen II engine, but probably not in a Gen III, and most definitely not in a Caldina, but that's just my opinion of the relative detonation sensitivity of the 3S-GTE variants. method's car is one I have no experience on so I can't comment, but I would say there's a lot more to detonation sensitivity than charge temperature.

[markbrown06]

that rule only applys with the ledded fuels

[ROBODISCO_20v]

If you have a look in the back of a NGK catalogue it had pictures of common problems with plugs. Easy way to diagnose a prob

[fivebob]

If you have a look in the back of a NGK catalogue it had pictures of common problems with plugs. Easy way to diagnose a prob

Not this problem, unless they're now printing pics showing the results of using Methylcyclopentadienyl Manganese Tricarbonyl (MMT), which IMHO is the most likely cause of the problem.

Also even with those pics as a reference most people don't know how to do a "plug chop" or how, and what part of the plug to read. 99% of internet mechanics will read them wrong anyway