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Discussion Starter · #1 ·
I've searched and can not find any post that tells what the correct gap is for the plugs. Anyone have it stored in their head?
 

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It's in your owners manual. The plugs should be pre gapped from the factory and are not adjustable anyway.
 

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What kind of spark plugs are you planning on getting? Some get Bosche, some get Champion, or NGK, etc..etc. Only way you'll know for a fact the gap, etc is all fine is if you get it from the dealer. And the BMW dealer sells them for $39 EACH. That's $234 + TAX..... for Just Freaking plugs. So, getting them from the dealer is out of question. Get em from Autozone, Kragen, etc. Usually $2-$10 each. I hear NGK coppoer plugs are great (about $3), they don't last as long as the iradiums, but are more responsive. They'll need to be changed every 30-35K miles or 3-4 yrs. Not a big deal, huh.

Let us know what you find out.
 

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Discussion Starter · #4 ·
I went with the NKG 7092. They are just the Platinum G plug for $2.59 at Oreillys. Since I did not get any responses right away so I gapped them at .032. All six plugs were at a different gap straight out of the box from .032 to .044. Thats why you always check any plug before insert. It took me about an hour to do it and I can tell you I instantly could tell a difference. Before it was running a little rough at idle like the injectors needed cleaning. But afterwards it ran very smooth. The original plugs looked pretty bad. My car is at 79,000 miles. For $16 for all 6 plugs, I think I will be changing them here on out after 20,000 miles. The only thing I need to fix now is the injector thats clinking and this thing will not even be heard when on.
 

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I went with the NKG 7092. They are just the Platinum G plug for $2.59 at Oreillys. Since I did not get any responses right away so I gapped them at .032. All six plugs were at a different gap straight out of the box from .032 to .044. Thats why you always check any plug before insert. It took me about an hour to do it and I can tell you I instantly could tell a difference. Before it was running a little rough at idle like the injectors needed cleaning. But afterwards it ran very smooth. The original plugs looked pretty bad. My car is at 79,000 miles. For $16 for all 6 plugs, I think I will be changing them here on out after 20,000 miles. The only thing I need to fix now is the injector thats clinking and this thing will not even be heard when on.
Interesting!

My stock NGK's went out right at 80k miles.
 

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Okay, so your injectors are making a metric ****ton of sound too, how are you going about to clean/repair them?
 

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I went with the NKG 7092. They are just the Platinum G plug for $2.59 at Oreillys. Since I did not get any responses right away so I gapped them at .032. All six plugs were at a different gap straight out of the box from .032 to .044. Thats why you always check any plug before insert. It took me about an hour to do it and I can tell you I instantly could tell a difference. Before it was running a little rough at idle like the injectors needed cleaning. But afterwards it ran very smooth. The original plugs looked pretty bad. My car is at 79,000 miles. For $16 for all 6 plugs, I think I will be changing them here on out after 20,000 miles. The only thing I need to fix now is the injector thats clinking and this thing will not even be heard when on.
You gapped a multi prong plug:confused:? Never heard of that one before. I've also never had one out of spec on the gap. Unless you are talking about single prong plugs, which the e39 never came with anyway.
 

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You gapped a multi prong plug:confused:? Never heard of that one before. I've also never had one out of spec on the gap. Unless you are talking about single prong plugs, which the e39 never came with anyway.
i hope so. but i just put in the champion single prong plugs. and gap them at .032
 

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i hope so. but i just put in the champion single prong plugs. and gap them at .032
Single prongs yes, gap them. You are supposed to. But multi prong plugs are pre gapped and not designed to be adjusted.
 

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i agree, muti prong should be pre gapped. but you nevey know, there's some one out there right now with a gapping tool, spending the last hr, gaping the same multi prong plug, going, dang it, there's got to be an easier way to do this.
but i just assume the op had single prongs.
 

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So...if BMW installed the high powered 4 prong NGK BKR6-EQUP spark plug in the M54 (double VANOS) engine that looks like this:



...and you replace it with a single prong 7092 NGK BKR6-EGP spark plug that looks like the one below...will it create any long-term problems?
 

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^^^^^^^^^No. As long as the heat range and gap are the same, you can use any plug you want. Neck length is also important, but not absolutely critical. Multi prong plugs, especially the ones with 4 ground electrodes, are junk. They're a gimmick. "They" claim that the spark has an easier chance of grounding if it has 4 places to go, because as we all know electricity takes the path of least resistance. In actuallity all the 4 electrodes do is block the flamefront from igniting the air/fuel mixture. They're junk.
 

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Discussion Starter · #13 ·
Yes, I installed the NGK 7092's which are single prongs. I can tell you the car is running very well and is idling much smoother now then before with original 4 prong. A spark plug is a spark plug. There will be very little difference with any new plug that you put in as long as the specs are similar (only talking prong numbers and not materials). As long as there is a spark that ignites the fuel thats all that is needed. There have been many debates about plugs and muti-prong plugs being able to better combust more fuel. Its mostly BS because once the fuel ignites, everything in the cylinder at that time will combust. The only thing that can really change the amount of combustion is the fuel and or air mixture in the cylinder. The only thing that is truly debatable in my opinion is the longevity of the different plugs. And obviously these expensive factory 4 prong plugs did not make it to 80,000 miles in this car. At $16 for all 6 of these plugs I would rather change them at 20,000 miles several times and keep them fresh than to keep the originals in there for 80,000 miles. A majority of cars these days can go 100,000 miles between plug changes and 99% of them use regular cheap platinum single prong plugs.
 

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Thank you gentlemen. :D
 

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^^^^^^^^^No. As long as the heat range and gap are the same, you can use any plug you want. Neck length is also important, but not absolutely critical. Multi prong plugs, especially the ones with 4 ground electrodes, are junk. They're a gimmick. "They" claim that the spark has an easier chance of grounding if it has 4 places to go, because as we all know electricity takes the path of least resistance. In actuallity all the 4 electrodes do is block the flamefront from igniting the air/fuel mixture. They're junk.
Are you referring to the OEM NGK 4-prong plugs being junk?

If the plug has 4 prongs, then does it have 4 electrodes?

Thank you!

Jason
 

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Are you referring to the OEM NGK 4-prong plugs being junk?

If the plug has 4 prongs, then does it have 4 electrodes?

Thank you!

Jason
Yes, I don't like the 4 electrode plugs that NGK or any other manufacturer makes. And yes, a 4 prong plug will have 4 ground electrodes. They are the same thing. It is a well known fact by people in the field that multi prong plugs perform worse than single electrode plugs. If I had 2 different plugs, one with a single electrode, and one with 4 electrodes, assuming all else is equal (neck length, heat range, etc) I would take the single electrode every time.

On a side note, single electrode plugs allow you to do what is referred to as indexing. Some of the oldschool guys on here will know what I am talking about. You put the plug in your socket, and mark the socket with a sharpie at the point where the gap is. Then you torque the plug down. What you want to do is get the opening of the gap to face the exhaust valve, which is the hottest part of the combustion chamber. This allows the spark to work in combination with the already present heat of the exhaust valve for more complete and faster combustion. This trick has been around for decades and is proven to work. Now, what if the line on your socket (which is line up with the gap on the plug) does not line up with the exhaust valve when you torque it down? Ah, they sell indexing washers in various thicknesses to put on the plug seat. Then torque it down again. Keep playing with different thicknesses until it lines up. Seems like a lot of work? Well, it is tedious indeed. But for those looking for those few extra ponies it might be worth it.
 

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Yes, I installed the NGK 7092's which are single prongs. I can tell you the car is running very well and is idling much smoother now then before with original 4 prong. A spark plug is a spark plug. There will be very little difference with any new plug that you put in as long as the specs are similar (only talking prong numbers and not materials). As long as there is a spark that ignites the fuel thats all that is needed. There have been many debates about plugs and muti-prong plugs being able to better combust more fuel. Its mostly BS because once the fuel ignites, everything in the cylinder at that time will combust. The only thing that can really change the amount of combustion is the fuel and or air mixture in the cylinder. The only thing that is truly debatable in my opinion is the longevity of the different plugs. And obviously these expensive factory 4 prong plugs did not make it to 80,000 miles in this car. At $16 for all 6 of these plugs I would rather change them at 20,000 miles several times and keep them fresh than to keep the originals in there for 80,000 miles. A majority of cars these days can go 100,000 miles between plug changes and 99% of them use regular cheap platinum single prong plugs.
So I assume that despite the fact that BMW factory installs 4 prong plugs that you know better than the BMW engineers? Likely not.
 

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So I assume that despite the fact that BMW factory installs 4 prong plugs that you know better than the BMW engineers? Likely not.
:rofl:

Accountants build cars, not engineers. BMW claims that these magical 4 prong plugs can go 100k before changing. That's so they don't have to pay to change them under warranty. They pay statisticians and actuaries to come up with ways the corporation can save money. If anyone thinks that any manufacturer puts every single piece in a car the way they do because of they are thinking about what is best for the customer, they need their head examined. Talk to any racer, any engine builder, or any enthusiast and they will all tell you that 4 prong plugs are at the bottom of the barrel. Not to mention they cost 3 times as much as a normal plug. A spark plug is a spark plug is a spark plug. As long as neck length, heat range, and gap are the same, it doesn't matter how many electrodes it has. You can't possibly think that this magical 4 prong plug was designed specifically for this motor. It probably fits hundreds of different cars. It's the same reason you can put the same pound per hour fuel injectors from a mustang in our motors and it will work just fine. They fit a wide variety of cars and Bosch doesn't make 500 different injectors. I'm not talking to you, just to everyone in general. So don't think I'm lashing out at you, I'm not.
 

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Discussion Starter · #20 ·
HeyGTXRAGTP, don't be a smartaz. Spark plugs are a real simple device and I do know a little about them. There could be a million reasons BMW engineers went with those plugs. It could be that NGK gave them a big discount to use those plugs. How many crappy tires have companies put on their vehicles where there are better make of the same out there. It's done all the time. No difference with other changable parts on any vehicle. Neither you or I know the real reason but I can tell you right now, using NGK 7092's will make no difference to this engine compared to using the original plug. Will I have to probably change them sooner than the others? Yes, but I could care less for the price. Oh, and engineers do not know everything. How many cars are out here that have major design flaws only to be detected after they already sold several hundred thousand units.
 
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