Z3 Changing Spark Plugs

[MORRIE]

I will soon be changing spark plugs in my '01 3 liter Roadster. I am considering Bosch Platinum plugs. I believe they make a Plat. 2 and a Plat 4. Any suggestions on which is better for street driving? Also, isn't the amount of torque 18.4 ft. lbs to install them? Please advise. Thanks!

[IgotBMW]

I recommend NGK BKR6EQUP.

[dkindig]

Ditto... NGK BKR6EQUP

[Z3racer701]

I don't like the multi-ground plugs, you get a little spark on each without really getting a good spark. A better plug would be a NGK BKR6EIX or a Denso IK20, at half the cost of these two would be a NGK BKR6EGP which has the same annode as the EIX plug with a convential square type cathode(ground).

[Telecomtodd]

You may also consider re-doing the valve cover gasket if it's been more than 30K miles since the last time it was changed.

[MORRIE]

Thanks to all of you for your input. Question: Is the amount of torque 18.4 lbs. when replacing the plugs? I do NOT want to over torque. Please advise.

[IgotBMW]

It's 18ft/lbs.

Apply anti-seize on the threads of the plugs as well.

[MORRIE]

Ordered the NGK- BKR6EQUP plugs today...will install them along with a new Air Mass Meter (sensor). I look forward to driving the car when it is "normal" once again. It has been sitting for about 6 weeks. Thanks to all of you for your input.

[mplazz]

It's 18ft/lbs.

Apply anti-seize on the threads of the plugs as well.

Remember the torque rating is based on a clean, dry thread. If you use anti-seize, you will need to lower the torque. Be careful and don't over-tighten.

you get a little spark on each without really getting a good spark.(ground).

Hmmmm... some research shows that any multi-electrode spark plug can only provide one spark at a time (according to NGK).
http://www.ngksparkplugs.com/product...multipower.asp

[Z3racer701]

Hmmmm... some research shows that any multi-electrode spark plug can only provide one spark at a time (according to NGK).
http://www.ngksparkplugs.com/products/cars_trucks_suvs/multipower.asp

Yes, one spark. However, when you remove the plug you'll see that it randomly sparks on either side, because both sides of the electrode are cleaner than the surrounding plug. It just seems that BMW went throught the trouble of placing the sparkplug in the middle of the combustion chamber, then why would we place a sparkplug in it that fires on one side or the other?

I do have the dual ground plugs in my 1.9, I've heard that the +4 type plugs are to be avoided due to too much resistance, but the next set in there will be one of the three I recommended.

[motorking]

[QUOTE=MORRIE;23574782]I will soon be changing spark plugs in my '01 3 liter Roadster. I am considering Bosch Platinum plugs. I believe they make a Plat. 2 and a Plat 4. Any suggestions on which is better for street driving? Also, isn't the amount of torque 18.4 ft. lbs to install them? Please advise. Thanks![/QUOTE

Morrie,
I work for autolite saprk plugs. Multi electrode plugs were used "back in the day" because they have good ignitabilty, required less voltage from the coil to fire. That was before fine wire iridium alloy plugs came out. That is the latest technology. I have given several sets of our XP3924 Iridium plugs to sevral BMW owners and they report very good results. They cost less than NGK iridium plugs as well and you can get them at any auto parts retailer or sparkplugs.com. Do not use antisieze on the threads, it changes the ability of the plug to reject plug tip heat to the cooling system. Watch the heat range video at www.youtube.com/cadzillals6 to see why.
here is a torque chart based on the latest BMW service bulletin


Good luck with your plug change.
Jay.Buckley@FramGrp.com

[Pima Roadster]

So what I understand from all of this discussion is that BMW OEM plug is a four electrode spark plug likely NGK. This is interesting 'cause back in the day, one thought was to index the single electrode style spark plug with the gap toward the intake valve. With the four electrode plug this would not be necessary. Now there is the iridium spark plug which is available with a single electrode. NEXT question is which style of spark plug places less stress or possibly "load" on the coils? I like the idea of a single electrode plug as it can be cleaned & re-gapped after perhaps half of its life span but that would be very difficult if not impossible with the four electrode type. Any comments are appreciated!

[Blacklane]

By the way, NGK recommends NOT using anti-seize on their plugs since (a) it's not needed, and (b) it leads to over-torquing. Their thread treatment already provides anti-seize properties.
http://www.ngksparkplugs.com/pdf/tb-0630111antisieze.pdf

Likewise Bosch Platinum and Iridium plugs have anti-seize treated threads:
http://www.boschautoparts.com/SparkPlugs/Documents/2213742_SP_PLAT_CONBRO_0412.pdf

There is a short discussion here:
http://forums.bimmerforums.com/forum/showthread.php?t=1209753

[Vintage42]

So what I understand from all of this discussion is that BMW OEM plug is a four electrode spark plug likely NGK.... Now there is the iridium spark plug which is available with a single electrode. NEXT question is which style of spark plug places less stress or possibly "load" on the coils? I like the idea of a single electrode plug as it can be cleaned & re-gapped after perhaps half of its life span but that would be very difficult if not impossible with the four electrode type. Any comments are appreciated!

In the case of my 1.9L, the OEM plug was two-electrode. Like you, I thought to upgrade to a popular single-electrode iridium. However, correspondence with NGK indicated that they recommended only one of their plugs for the 1.9L because it matched the resistance of the coils and had the right tip extension. The correspondence made me realize that one may use a "style" of plug that is appealing, only if the manufacturer has made and recommended that plug for the engine. As for cleaning and re-gapping, I think that applied to old cars and bikes that could foul and soot and erode their plugs, but is not recommended for modern engines whose plugs last for 30-60,000 miles and are then discarded.

Here's the email from NGK about resistance:

From: Info <Info@ngksparkplugs.com>
Subject: RE: NGK Form Mail
Date: November 29, 2012 5:02:39 PM EST
To: ________<_______@insightbb.com>
The 1.9L does only use the BKR6EK, but the 2.8L can use the BKR6EIX...
The BKR6EK has a 6.0mm firing position with two ground electrodes and a 1K ohm internal resistor. The BKR6EIX has a 3.5mm firing position, with a single ground electrode and a 5K ohm resistor. The firing position might create some engine response lag, but the real concern in the 1K ohm resistor. The ignition in the Z3 is setup for a 1K Ohm resistor and the 5K resistor may cause random misfires. Here is a picture to explain firing position visually. I would realistically not recommend the BKR6EIX for the Z3. Instead I would recommend a PFR6Q #6458. This is a fine wire Platinum center electrode, which will perform just as well and the IX and it has the correct 1k Ohm resistor internally.
Best Regards,
Andrew Hauenstein
Technical Training Specialist
NGK Spark Plugs USA Inc

[Pima Roadster]

Wow, the plot thickens as they say. The difference in ohm resistance would eventually cause problems with the coils. So if the OEM plug for a 3.0 is a four electrode plug, one should stick with it even if "better technology" offers another perhaps better mouse trap.

[gmushial]

Yet if one goes to the NGK site... this is what is recommended for at least the '99 2.5L (which includes the EIX)... personally I'm happy with the BKR6EGPs.



A quick follow up: just got an email back from NGK tech support - seems both the BKR6EGP and the BKR6EIX are 5k plugs. [also seems that most post mid-90's ignition systems are designed around 5k plugs - the 1k plugs date from the 70's and 80's]

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Further follow up: assuming a 10ua (microamp) current through the plug at discharge [haven't found exact numbers in any of my reference material here, nor on the web - all I can find are references to "a few microamps" - so I've used 10 as a safe number] - then the 4k ohm increase (to 5k from 1k) will cause a huge drop at the plug of .... 0.04volts... this is in the context of a 35-45kv system, ie, well buried in the statistical noise.

-------------------------

A further follow up: I emailed NGK again, explicitly asking if the IX or EGP etc are appropriate plugs for the Z... this is the reply I just received back:

"
Hello Greg,

I think there was some miscommunication. The 1999 Z3 2.5L uses an NGK BKR6EQUP #3199 as the OEM spark plug. The 3199 has a 5K ohm resistor and the BKR6EGP is a suitable replacement for the Z3. I don't know the context of the original statement, but I apologize for the miscommunication of technical information.

Best Regards,

Andrew Hauenstein
Technical Training Specialist
NGK Spark Plugs USA Inc

"

-------------------

One last follow up: if one plugs into the NGK site all the possible Z years and engine combinations: the 1.9 is different, but all the 6 cylinder engines generate the above table of acceptable plugs.

[Vintage42]

... One last follow up: if one plugs into the NGK site all the possible Z years and engine combinations: the 1.9 is different, but all the 6 cylinder engines generate the above table of acceptable plugs.

Yes, my question to NGK's Hauenstein was whether any other plug could be used for the 1.9 4-cylinder, besides the one BKR6EK they listed, and he said:"The 1.9L does only use the BKR6EK..."

He sent me their application chart which showed the 4-cylinder only took the one NGK BKR6EK, while the 6-cylinder took a total of five other various NGK plugs.

My point was to use what the mfr recommends. I made the mistake of buying these plugs for my 1.9 Z3 based on an eBay vendor's claim:
http://www.ebay.com/itm/96-98-BMW-Z3...sories&vxp=mtr

I had to provide the emails from NGK to get a Return Authorization from the vendor.

[Mach Tuck]

Great info.