Spark Plug Diagnosis

Hey everyone. I've already compared the plugs to a diagnostic chart but I'm hoping you all might give me some good unbiased input. These were replaced today on my '05 X3 with 97K miles on the odometer. I've only had the vehicle a few weeks so I'm not sure if the plugs were original or not; perhaps they were changed at the dealer once before. They seem to show good signs to me, but what do you all think? Anything I might need to know?

Looks like a good burn.

Looks pretty average for plugs that have been in there for awhile....

Originally Posted by Fast Bob

Looks pretty average for plugs that have been in there for awhile....

Do you think they're the original plugs?

Originally Posted by halltristan

Do you think their the original plugs?

Could be....it`s not unusual for plugs to go 75-100K miles on modern engines.

I wouldn't be surprised if those where your original plugs. They don't appear to show any signs of problems.

Originally Posted by Fast Bob

Could be....it`s not unusual for plugs to go 75-100K miles on modern engines.

The 4 ground electrode Plugs are especially made for 100k mile intervals.

On tests that have been done each electrode has about 25k in them so 4 of them would be 100k or close to before needing a change. Great plugs for longevity not for performance.

Originally Posted by nivo

The 4 ground electrode Plugs are especially made for 100k mile intervals.

On tests that have been done each electrode has about 25k in them so 4 of them would be 100k or close to before needing a change. Great plugs for longevity not for performance.

What about the plugs that only have one? (That's what I switched them out for: NGK - Iridium)

Originally Posted by nivo

The 4 ground electrode Plugs are especially made for 100k mile intervals.

On tests that have been done each electrode has about 25k in them so 4 of them would be 100k or close to before needing a change. Great plugs for longevity not for performance.

Funny, my Lincolns have single grounds on the plugs and they have a 100K mile service interval. They still looked okay at 100K miles when I changed them.
I'm not sure why BMW picked the four ground design, but I don't believe your theory at all. All four grounds should erode at about the same rate. There's no way that one is used up, then the next, and so on. Look at the pictures of the removed plugs, all four are still there, and all four probably have about the same wear.

I like to stick with what was designed in, so for the BWM, I replaced the plugs with ones with four grounds. For the Lincolns, I used single grounds.

Originally Posted by halltristan

What about the plugs that only have one? (That's what I switched them out for: NGK - Iridium)

They work just fine.
Best spark plugs are one with silver for lowest resistance, Iridium lasts long and that is why it is used. It has a higher resistance then silver but they offset this with stronger material and they are able to make the center electrode smaller and sharp. The sharper center electrode is the reason why iridium spark plugs are the rave for many.

Platinum plugs are made for long wear/service intervals not really performance.

Metal resistance from least to most:

Silver
Copper
Iridium
Platinum

Originally Posted by joegr

Funny, my Lincolns have single grounds on the plugs and they have a 100K mile service interval. They still looked okay at 100K miles when I changed them.
I'm not sure why BMW picked the four ground design, but I don't believe your theory at all. All four grounds should erode at about the same rate. There's no way that one is used up, then the next, and so on. Look at the pictures of the removed plugs, all four are still there, and all four probably have about the same wear.

I like to stick with what was designed in, so for the BWM, I replaced the plugs with ones with four grounds. For the Lincolns, I used single grounds.

And I am sure the lincoln uses Platinum plugs correct?

If you bench test plugs as much as I have you get to see and know how they end up working, I also have helped develop spark plugs on certain applications.

multiple tip spark plugs are designed for the reason I have talked about before. I have tested many spark plugs and ones that do offer some performance over others are silver spark plugs. Others like pulstar, E3 etc are just gimmick plugs.

I remember when the quad-electrode plugs were first introduced around 25 years ago, and recall that the reason given for their design was to be more efficient in engines with higher-than-usual combustion chamber pressures, i.e., forced-induction and high-compression N/A engines. There were lots of turbo motors around back then.... it`s always been controversial as to whether the plugs actually help or not....