new bad plugs?

[Jim mac]

my last 200x old plug looked bad, installed a new ngk ug and chased what I thought was a ignition problem until I did the pull the plug and there's no spark. put the old plug in and it fired right back up.
now the new 200x, old plug looks iffy, grabbed a new ngk plug (I bought 4 on ebay) and the new plug doesn't fire.
Anyone run into this issue? jim

[Shep1970]

Yes, beware of made in china ngk copies- ebay/amazon sellers have been selling them for a few yrs and they are junk.

shep

[Jim mac]

I watched a you tube video about fake ngk plugs. one thing they posted is the P in Japan should have a line on the bottom of the P which mine did not and the slashes are off. jim

[car46999]

I too have recently had an issue with counterfeit spark plugs. Unfortunate for me they were on a V6 in a minivan that are hard as heck to change out. My symptom was misfires way before they advertised life that I have previously gotten out of the same genuine plugs.

I have decided that no more Amazon or Ebay spark plugs for me.

[ATC200X4716]

I've gotten bad genuine NGK plugs out of the box. This was 25 years ago even. Used to refer to them as NFG plugs not NGK plugs.

[El Camexican]

Same here. RedSox set me up with a US rep, but they never called back. Probably no point, they’ll never catch the people doing this and even if they did, they’d have a tough time prosecuting them overseas. The tell on my plug wasn’t that it didn’t work, it was that the lettering was a really cheesy.

[Footy]

Thanks for this info. I will buy the plugs at my local dealership. I still have 2 family owned shops near me. Almost all are big box stores now and I hate them.
20 years ago I had a 1983 ATC200E and it would only run on Champion spark plugs. The NGK would start and run but would foul after only a few rides. Champion plugs would last for years. It was not burning oil as I had rebuilt the top end. I never did figure that one out.

[207wheelin]

I once had a Yamaha snowmobile that would run for a few hours then die. Swap in a new plug and it would fire right up again. No fouling just dead. It's the only time I've ever seen such a thing.

In the auto repair industry NEW stands for Never Even Worked.
Take care
Corey

[El Camexican]

I once had a Yamaha snowmobile that would run for a few hours then die. Swap in a new plug and it would fire right up again. No fouling just dead. It's the only time I've ever seen such a thing.

In the auto repair industry NEW stands for Never Even Worked.
Take care
Corey

That can happen when your jetted a little rich. I had a bike that would kill plugs sometimes as fast as I could put them in (Yamaha btw) the fix was one size down on the pilot jet). I’ve got plugs that are 10 years old in 2 strokes, you never know when they will die out on you.

As far as the eternal debate between NGK, and champion brands I just stick to which ever one came with the vehicle, but it does seem that the fit and finish of NGK is superior.

[MrConcdid]

Yep I got a counterfeit NJK it sparked outside of the cylinder while testing but not inside under pressure. that took me a minute to figure out. Needless to say I hurled it across the shop, watching it shatter against the far wall.
lol, true story

[FourtyCaliber]

I worked for a number of years at a well-known USA spark plug manufacturing facility in engineering and I can tell you that non-sparking plugs aren't a phenomena of just Chinese imports. Things do happen in the manufacturing process. Did you happen to unscrew the terminal nut from the top of the plug and see what may be going on inside? If you have the FISS (Fired-In-Suppressor-Seal) type plug that won't be possible. But, on a standard type plug with a nut terminal, you can heat it up and remove it (cemented in). Inside the insulator should be a spring, and below that either a resistor, or a suppressor. Below the resistor you should see the top of the centerwire assembly. The plug may be missing the spring, either the resistor or suppressor, or there could be something impeding the contact between the centerwire and the resistor. The centerwire is comprised of multiple materials resistance welded together and it's always possible, too, that a weld between the different components was faulty resulting in no continuity. Another thing that could cause a non-sparking condition (at the ground and centerwire electrodes) is a crack in the insulator which will result in the electricity following the path of least resistance and, usually, arcing out inside the hollow of the shell, or onto the seat where the insulator sits inside the shell. All spark plugs are tested for functionality before packaging, but that doesn't preclude a few bad ones getting out now and then.

Actually, thinking back, I had a bad spark plug in a brand new Honda CR125 that I bought back in 1981, and this was long before they started manufacturing plugs over in China. I got the bike home and it would fire, but it would just not run right. Supposedly, the Honda dealer went through the bike when I purchased it and before they released it to me to take home. The problem ended up being a crack in the insulator core nose near the firing tip on the plug. The crack was low enough to where the spark was arcing to the end of the shell face, which was enough to start the engine, but it wasn't arcing at all between the two electrodes where the spark needed to be for proper ignition. It was a brand new plug with a hairline crack, which is very common. Ceramic insulators are handled in bulk, and get jostled around in large containers, which can result in cracks and chips in the ceramic. Of course, this was several years before I even went to college and started working at the plug manufacturer, but just goes to show that bad plugs do get through inspection and will continue to get through. At least until everything goes electric.

[Jim mac]

went back and decided to start over. when I first got the trike it sparked on its old plug but not very good. checked the specs on the coil, stator swapped the cdi and cleaned up the wiring.
I had a complete china ignition system and it still sparked sporadic. So today, went and rechecked the stator. reading 116 ohms which was withing the specs bit getting to the bottom according to one website. I had a new stator sitting in my parts bin, checked it and it reads 230. so I swapped it and it starts fine on the old plug, new ngk plugs everything! jim

[ATC King]

A bit different but I've been primarily buying plugs from physical dealers and parts stores to avoid counterfeit Chinese ones. I will buy from reputable online stores too, but that's usually just larger orders to meet their free shipping minimum. No Ebay or Amazon plugs for me.


I was a bit alarmed last time I bought some Autolite plugs for my truck at a local parts store. Four were manufactured in Mexico and two were Chinese, which I didn't notice until I got home with them. I went back to exchange the two Chinese ones but that's all they had in stock. I appears the new Autolite #45 plugs for a Ford 4.9 are now manufactured in China. I'm going to stock up on the Mexico manufactured plugs before they run out.


The boxes and plugs differed in appearance between the two, no way in hell I'm going to mix them. If China can't even get the physical appearance of the plug and box the same, no way they are the same on the inside. Glad I caught it because the differences were somewhat subtle.