Plugs (95770 v. 97506), gaps, and the N54

iminhell1

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Plugs will let you know when they're not happy for gap or heat range. I've had no better luck than the OE S55 plugs, but I run pump only. Stock gap (.031") on hybrids up to 24psi without a misfire on old ass Eldors.


I hate you.
I'm on 0.017" and seem to have ignition issues.

So I might just climb a limb and say that there are not actually ignition issues, but infact fuel issues?
 
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fmorelli

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... or at least not spark plug gap issues ...

I moved to 0.022" gap, but I now have a #2 cyl misfire and a 2DED ... I swapped coils and still #2 unhappy. My money is on the high quality bimmerlife harness, but I haven't gotten a multimeter on the #2 coil plug yet. Same thing happened on the 1M which chuffed a connection. We'll be making a real harness soon, so this sketchy shit doesn't happen.

Filippo
 

Msport335

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Just yesterday i went from bosch coils and 95770 plugs gapped at .020 to Eldor coils and 97506 plugs gapped at .020 and had cold start misfires in cylinders 1 & 6. When running the bosch and 95770 i had cold start hiccups but no misfires.... not sure what to do at this point.

both setups were fine once car warmed up. just today i put my 95770 back in with the new Eldor coils and still had cold start hiccups....pulls seemed strong other than minor timing corrections up top

FBO N54, PS2@ 28psi, 94 octane + lots of METH
 

RSL

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I hate you.
I'm on 0.017" and seem to have ignition issues.

So I might just climb a limb and say that there are not actually ignition issues, but infact fuel issues?
Hard to say, but where it starts misfiring might give some indication. I've always had a tendency not to do anything ignition related until there's a reason to and I just haven't had ignition problems so many seem to have on these cars. Part of it is that I don't use E85, part of it is surely tuning and how things are being asked to perform. I have hybrids and am not trying to wring every bit out on boost or timing because I'm only on 93 octane.

I go against the grain on a lot of things that are commonly pushed on this platform, but I've been around a while and have tested a lot of things myself. What I can say is that both the de facto 5992/95770s and 97506s were both more prone to misfire in my car on my tune than S55 plugs, with the 97506s being the worst. It's extremely easy to compare when you have a strong tune and find that 1 plug needs to be at .020" gap to not misfire (would probably need .017-.018 at my new DA), another needs .022" gap and another handles it at .031" without changing coils or anything else. All I can say is you won't know until you try and see for yourself, no matter what the vendors, tuners, masses or anyone on the internet says, including me.

I replaced my original set of 35k mile S55 plugs with 97506s at the end of last year to try the 2-step colder N20 plug. I immediately had to gap them down twice to stop misfires on the same tune the old S55 plugs were running fine on with the larger gap. I just moved to a completely new environment (to sea level from 1000'), flashed my normal tune back last week from the light tune I've been running on for the last few months to check it here and the first hit (97506s @ .020" which were barely OK for lighter low end torque and 19psi peak @ 1000') misfired at just 16-17psi before it even got to peak torque. Installed the new S55 plugs at stock .031" that showed up yesterday with the same 50k+ mile Eldor coils and that same tune and tank of gas, it pulled clean straight through at 21-22psi. Age wasn't an issue on the 97506s, they were a misfire problem from day 1, requiring a very small gap to avoid it, and only had about 8k miles on them when I took them out yesterday. Obviously, it wasn't the coils either.

OE S55 plugs are good and dirt cheap right now for some reason. Just paid $42 for all 6 and am going to order a couple more sets before they come to their senses. For comparison, when the S55's first came out, I paid about $180 for the set from the same place. 97506s are $108 there right now. In other words, if anyone hasn't tried S55 plugs and is considering it, now seems like a good time :)

@fmorelli I couldn't get clean pics of the wells when I swapped the plugs, but black marks on the gaskets are random "spots". I'd expect a leak wouldn't have sharp, clean edges and wouldn't be well-defined separations. Maybe a build up just broke cleanly in places when removed or maybe it was whatever spots were already on the taper from the last change, but not that concerned about it since it hasn't been an issue with close to 90k on the car now and has been like that since first plug change.
 

Rob09msport

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Aren't s55 n20 and 97506 all the same ? Asking not telling cause i feel they are always referenced incorrectly and I'm not sure what's what at this point.
 
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RSL

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Aren't s55 n20 and 97506 all the same ? Asking not telling cause i feel they are always referenced incorrectly and I'm not sure what's what at this point.
NGK are OE BMW plugs for N20. 12120039664 (BMW P/N) and SILZBR8C8S or SILZBR8D8S or whatever letter they're using now (NGK 97506) should be the same. S55 plugs are Bosch. S55 plugs are 1 heat range colder, N20 plugs are 2 ranges colder and not the same construction materials AFAIK, but both have the same firing tip depth.
 
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Rob09msport

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In that case i think I'm giving s55 a shot
And fillipo you should try moving harness i had a faulty one that was replaced you can even run stock coil temporarily in place as per alex. I did this for 3 days while waiting for replacement.
 
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RSL

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BTW, S55 plug BMW P/N is 12120039634. Bosch number was from the Motorsport division and don't know if any construction info was ever released separately from them under their number in the last few years: ZMR5TPP330.

The seller I got them from for $42 sounds like eee see ess, but quick Google shows several others have them for ~$6.75/each too now.
 

matreyia

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... or at least not spark plug gap issues ...

I moved to 0.022" gap, but I now have a #2 cyl misfire and a 2DED ... I swapped coils and still #2 unhappy. My money is on the high quality bimmerlife harness, but I haven't gotten a multimeter on the #2 coil plug yet. Same thing happened on the 1M which chuffed a connection. We'll be making a real harness soon, so this sketchy shit doesn't happen.

Filippo


OK, update:
I walnut blasted my car, changed HPFP, all fuel sensors then installed new NGK 95770 with gap .030 using the BimmerLife coils. Then I flashed to MHD 7.1 version... and the oscillations seem to be gone, car is super responsive and eager, crazy power and torque like old days.

Caution on NGK sparkplugs... I have read multiple forums and even some vendors that NGK 95770 come pregapped at .031... I want to inform everyone that was not true in my case. As a matter of fact every single NGK plug that I measured each had totally different gaps ranging from .028 to .031. So do your due diligence and make sure you gap them. Do not trust that they are .031 from factory.

VT
 

doublespaces

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The N20 plugs are 97506. The N55/S55 equivalent plug is the 95770 and 5992. There is a second set of N20 plugs for Flex Fuel and they are an additional step colder. The C/D/E in the NGK SILZKBR8D8S naming scheme refers to the thread depth of the plug. This is why some spark plugs extend into the cylinder deeper than others. The FAQ outlines this quite well in fact:
https://bmw.spoolstreet.com/threads/n54-the-best-plugs-injectors-and-coils-thread.1094/

If you take a page out of the bootmod3 wiki, the S55 guys run the N20 plug anyway, as the S55 plug is the same heat range as the N55 but its a worse quality part than the N55 plug and is prone to cracking:

When tuning your BMW N55, S55, S63TU it is recommended to go with 1-step colder spark plugs. We've found the NGK SILZKBR8D8S (97506) in the picture attached working great when gapped to appropriate spec. If you'll be running less than 25psi of boost we suggest a 0.020" gap, or 0.018" if planning to go higher. In most cases though we just go with the 0.018" gap and call it a day.
One great source is from: http://www.sparkplugauto.com/
NOTE: S55 OEM plugs are highly prone to cracking even on stock vehicles. Some have used them in the past on their N55 motors without realizing the heat range is identical and they're in fact of worse quality than N55 OEM plugs. We don't suggest using the S55 OEM plugs when tuning your motors and the NGK SILZKBR8D8S (97506) have been found to be far better.

So in my opinion, people should simply use the N20 plug, I don't know why everyone keeps trying something else as I've not heard of anyone have problems with them.
 
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fmorelli

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The C/D/E in the NGK SILZKBR8D8S naming scheme refers to the thread depth of the plug. This is why some spark plugs extend into the cylinder deeper than others. The FAQ outlines this quite well in fact:
https://bmw.spoolstreet.com/threads/n54-the-best-plugs-injectors-and-coils-thread.1094/
Thanks for bringing a tabla rasa and flashlight to the discussion! I remember reading this thread some time back. Unfortunately I'm a bit dense and can't seem to decipher the coding. The thread talks about positions and reading from the right. But the actually text quoted is direct from NGK. They also provide a corresponding PDF. Neither of those two seem to correspond with the format, SILZKBR... . What am I missing?
So in my opinion, people should simply use the N20 plug, I don't know why everyone keeps trying something else as I've not heard of anyone have problems with them.
Interesting. I have the NGK SILZKBR8D8S sitting in the box. I don't see why the 97550s shouldn't work - I'm FBO/inlet/outlet stock turbos on E80 with custom tune. I need to get past the BL harness issue, but I'd imagine the 95770s shouldn't hiccup at 0.022" driven by the R8 coils. I have the dreaded #5 cyl 3 deg correction going on, and I've read a number of myths on that. I have a low side PCV system to install and need to plug heads. At 30k miles my intakes look ok, but once both high and low side PCV are done, I plan to walnut blast and hopefully never look back.

Filippo
 

doublespaces

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Thanks for bringing a tabla rasa and flashlight to the discussion! I remember reading this thread some time back. Unfortunately I'm a bit dense and can't seem to decipher the coding. The thread talks about positions and reading from the right. But the actually text quoted is direct from NGK. They also provide a corresponding PDF. Neither of those two seem to correspond with the format, SILZKBR... . What am I missing?

I thought I had this figured out at one time, but none of it makes sense to me today.

fmorelli said:
Interesting. I have the NGK SILZKBR8D8S sitting in the box. I don't see why the 97550s shouldn't work - I'm FBO/inlet/outlet stock turbos on E80 with custom tune. I need to get past the BL harness issue, but I'd imagine the 95770s shouldn't hiccup at 0.022" driven by the R8 coils. I have the dreaded #5 cyl 3 deg correction going on, and I've read a number of myths on that. I have a low side PCV system to install and need to plug heads. At 30k miles my intakes look ok, but once both high and low side PCV are done, I plan to walnut blast and hopefully never look back.

Filippo

The 97550 will probably work fine for you. I just haven't heard of anyone having issues with the N20(97506) plug.

In writing this post, I came across the B58 plug: NGK 94201 - SILZKGR8B8S

It has all the same specs as the NGK 97506, except it sayts GR8 instead of BR8 in the name. So, what does the G and B mean?
 
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RSL

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The N20 plugs are 97506. The N55/S55 equivalent plug is the 95770 and 5992. There is a second set of N20 plugs for Flex Fuel and they are an additional step colder. The C/D/E in the NGK SILZKBR8D8S naming scheme refers to the thread depth of the plug. This is why some spark plugs extend into the cylinder deeper than others. The FAQ outlines this quite well in fact:
https://bmw.spoolstreet.com/threads/n54-the-best-plugs-injectors-and-coils-thread.1094/

If you take a page out of the bootmod3 wiki, the S55 guys run the N20 plug anyway, as the S55 plug is the same as the N55
but its a worse quality than the N55 plug and is prone to cracking:



So in my opinion, people should simply use the N20 plug, I don't know why everyone keeps trying something else as I've not heard of anyone have problems with them.
I used the OE BMW N20 plugs, no idea which NGK part they cross to other than the stock number. I vaguely remember the letter being a construction material difference or something else and that they stopped selling the highest letter and went back to the earlier one for some reason (E->D?). Maybe that's changed since I last looked 9 months ago.

Tried the S55 plugs first (2015), they were in until end of 2017 at big gap without issues. No cracks, no leaks, no misfires, no shitty small gap idle or surging. Tried the 97506s since everyone raved about them and they were a problem from the first pull after install. Had to gap them to 2/3 the size to run the same tune and would've needed to gap them even smaller to keep them clean at the new lower elevation.

All I'm reporting is my firsthand experience between the plugs. Everyone is certainly welcome to spend their money on what they think is best or, better yet, actually test options to find out what works best in their car.
 
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doublespaces

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I used the OE BMW N20 plugs, no idea which NGK part they cross to other than the stock number. I vaguely remember the letter being a construction material difference or something else and that they stopped selling the highest letter and went back to the earlier one for some reason (E->D?). Maybe that's changed since I last looked 9 months ago.

Tried the S55 plugs first (2015), they were in until end of 2017 at big gap without issues. No cracks, no leaks, no misfires, no shitty small gap idle or surging. Tried the 97506s since everyone raved about them and they were a problem from the first pull after install. Had to gap them to 2/3 the size to run the same tune and would've needed to gap them even smaller to keep them clean at the new lower elevation.

All I'm reporting is my firsthand experience between the plugs. Everyone is certainly welcome to spend their money on what they think is best or, better yet, actually test options to find out what works best in their car.

Appreciate sharing your experience. I suppose this is modification dependent, perhaps even so much as fuel and what ignition you were running? I've only ran them since I was single turbo, from a 1 bar 91 octane map up through several ethanol revisions. Misfires haven't really been my issue so far.
 

RSL

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Appreciate sharing your experience. I suppose this is modification dependent, perhaps even so much as fuel and what ignition you were running? I've only ran them since I was single turbo, from a 1 bar 91 octane map up through several ethanol revisions. Misfires haven't really been my issue so far.
No question in my mind fuel and tuning have a lot to do with it, but would expect ST and/or high E85 content to change things up a lot. Aftermarket coils should help no matter what, but they're obviously not a cure all.

I'm on 15T hybrids, 93 only and the same Eldor coils I installed in 2014. Only diff for me is the 2 plugs, so obviously something about the 97506s has a much harder time lighting near peak torque. S55s breeze through more on a larger gap. When the 97506s misfired, it was always low RPM high torque, but work fine at high RPM.

I never disabling multi spark and am on pencil coils, so never played with dwells either. Not sure if either would've helped that plug in my car, but would have to assume if it did, would make the S55s work better too.

No reason to change anything if it's working properly and you're happy with it, but if there are issues, S55s are a worthwhile option and are super cheap to test out now.
 

doublespaces

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No question in my mind fuel and tuning have a lot to do with it, but would expect ST and/or high E85 content to change things up a lot. Aftermarket coils should help no matter what, but they're obviously not a cure all.

I'm on 15T hybrids, 93 only and the same Eldor coils I installed in 2014. Only diff for me is the 2 plugs, so obviously something about the 97506s has a much harder time lighting near peak torque. S55s breeze through more on a larger gap. When the 97506s misfired, it was always low RPM high torque, but work fine at high RPM.

I never disabling multi spark and am on pencil coils, so never played with dwells either. Not sure if either would've helped that plug in my car, but would have to assume if it did, would make the S55s work better too.

No reason to change anything if it's working properly and you're happy with it, but if there are issues, S55s are a worthwhile option and are super cheap to test out now.
Have the N55 and S55 plugs converged to a single part number from NGK?
 

fmorelli

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Spent a bit more time on the NGK numbering system over breakfast this morning - NGK lists 4 numbering systems, none which correspond to the Iridium IX plugs we are talking about. Unfortunately NGK's product web site doesn't even provide all the parameter information for the SILZKBR8D8S.

I plan to call them today and ask for the numbering system reference for this plug set.

Filippo