Sparkplug question

[randyjaco]

The other day I was driving and developed a miss. I checked the plugs expecting the problem to be much more serious. I have the Bosch +4 platinum jobbers with the four electrodes. When I pulled #4, I found that the 4 electrodes were completely erroded away all the way down to the base of the threads. The other plugs looked fine. Anybody got any suggestions on what maybe the problem and is this an indication of another problem? The counter guys at the auto parts store hadn't seen anything like it.

The car is a 94 325 with about 130k on it with a Comforti chip and
runs great now and before.

TIA

Jake in Escondido

[Wayne 962]

Can you post a pic, I'm curious!

-Wayne

[Jared at Pelican Parts]

First off, I've heard that Platinum plugs really dont work well in these cars. You might be better off with regular Bosch supers.

I dont know what would have caused the artms to wear down. I've never seen anything like that. I'd need to see a picture.

[blkongry]

very odd... sounds like a defective plug, if it is the only one like this. If it was a way the engine is set up, or running hot because of the chip or some other adjustment, the wear should be even across all six plugs... but to have just one totally fried is weird, especially that it was the four electrodes that were gone... which I think are the annodes. With oddities like this, the only thing to do is to check your plugs as they age. If that cylinder eats the plug again, then there may be more to the story.

[Zyvek]

Originally posted by Jared at Pelican Parts
First off, I've heard that Platinum plugs really dont work well in these cars. You might be better off with regular Bosch supers.

I don't mean to be a wise guy, but the dealer installed plugs (had 100K major service performed by PO) that I replaced on my 325i yesterday were "Bosch Platunium BMW plugs" (this was printed on the spark plug).

We got a kick out BMW getting Bosch to make a "special" plug for them. Just makes me wonder if anything is different on these plugs other than the high dealer price and the three extra letters printed on the plug.

FWIW, just thought it was interesting.

[blkongry]

I work for a company who manufactures a product under several names... same product, but for different retailers and OEM customers. I highly doubt the 'BMW' plug is anything different than the standard Bosch line, it's just that batch was made as an OEM product for BMW. Interesting though... why would they waste time getting even the spark-plug labeled for them. Other than because the bottom line always has a dollar sign by it ...$$$$

[Wayne 962]

If it says BMW (or Porsche), on the box, you can charge 200-400% more...

Plain and simple.

-Wayne

[randyjaco]

I will be glad to attach pictures, but I can't figure out how.
When I click Attach Multiple, nothing happens and I can't find the browse button at the bottom. What is the secret?

Jake

[blkongry]

Hmm... when you hit Attach Multiple, an attachment window should open. If not, try to right click, then select "Open in a New Window" and see if that works.

[Larry F.]

On platinum plugs being recommended by BMW or not, it varies by engine and year. BMW (and aftermarket suppliers) strongly recommended against platinums for the M30 motors in my E28's. BMW dealers in the Seattle area now recommend the platinum +4's for my S52 in my E36. Don't know what changed technically, just the recommendation.

[blkongry]

So, what's the difference between platinum or not? The platinum is just for wear characteristics... the platinum doesn't degrade as much and maintains a more stable spark... so why would anyone discourage it from being used?

[randyjaco]

Evidently I don't have access to the ability to attach pictures. I turned off my pop-up blocker and got nothing when I hit "Attach Multiple". I then right clicked it and opted for opening in another window and got a message that the page couldn't be displayed.

Any other thoughts on how I could post the pictures? If you will email me at randall@fontaine-etal.com I can send you the pictures of the sparkplug.

Jake

[Jared at Pelican Parts]

never seen anything like this before

[Dave at Pelican Parts]

Quality control on the cheapie Bosch platinum plugs (the ones with just a tiny speck of platinum in the center electrode) has been pretty poor. I know several people who have had the platinum un-bond itself from the rest of the plug and come bouncing out into the combustion chamber, or weld itself to the outer electrode.

As far as I can tell, the "+4" plug (and its cousin that only has two electrodes) are just the same crappy plug with extra outer electrodes. I would recommend staying away from any of them, frankly. I also have heard anecdotal evidence (e.g., stories) about other plugs curing minor driveability problems when they were installed in place of Bosch platinums. In fact, I had a no-start in a previous 914 that seemed to be in part due to those plugs.

Note that Bosch makes some very good plugs, including some platinum ones. But the good platinums are pretty pricey and harder to find than the cheapie ones.

I cannot recommend a replacement plug for the BMWs, though, as I haven't been cralwing around in them enough. In my 914, I use Bosch Copper plugs. In my Japanese car, I use NGKs. Both are fine plugs, but may not be up to snuff in the BMW application. (Might be great, might require replacement sooner than the regular service interval, or something else may happen--I don't have any data about that yet.)

But I would at least consider some alternative to the cheapie Bosch platinums. I consider them to be junk.

--DD

[blkongry]

Wow, you don't see that very often. What I do see is scoring on the side of the ceramic that shields the center electrode. It looks like the plug just took a dump and started arcing from the side. This would make sense because the spark would be harder (it would have to build up more to make a longer leap), less directed, and more destructive... leading it to eat away at the closest place for it to ground out, which is why all four of the outer electrodes are gone. Looks like the plug went bad early and has been misfiring for quite some time. Destruction like this doesn't happen quickly.

It looks from the pic (hard to tell though) that the center electrode is still there, and with the black carbon on it, it has been firing at that location for a time. I wonder what went bad??

[Wayne 962]

Hot dog, that's bad. And on all four prongs, so you know something was going on there. I would guess it wasn't properly plated, and the sparks just ate away the metal until it was gone...

-Wayne

[randyjaco]

As an update, I checked the replacement plug today. It has about 400 miles on it. The business end looks like it just came out of the box. There is no evidence of errosion. I guess the problem was a defective plug.

[Larry F.]

Thanks for getting the picture out there! What a fantastic failure!

[Wayne 962]

Any chance I can borrow that plug? I'd love to take some real high-res shots of it for the book!

-Wayne

[randyjaco]

Wayne,

You may have it. I am sure never going to use it. Just tell me where to send it.

Jake in Escondido