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BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > Technical Forums > N55 Turbo Engine / Drivetrain / Exhaust Modifications > Cracked Ceramic Spark Plug in Cylinder
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      04-04-2020, 04:49 PM   #1
pw0n
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Cracked Ceramic Spark Plug in Cylinder

Own an F32 435i running BM3 stage 2 w/ NGK 97506 gapped @ 0.026" (but this may be a bit questionable...).

It's been about 5k mi since I changed my plugs. Car's been hesitating a bit more 5-10min after a cold start. I've read hesitation after a cold start can be normal, but it's much more than I rmbr before Stage 2 + new plugs and shortly after; so I decided to regap.

Couple of questions/concerns:
1) Each spark plug well had brown/black residue. Not sure if it's oil - I was able to vacuum them right up. One of the ignition coil also looks a bit brown/orange, but no signs of rust on any of them. Anyone know what this is and if it's normal? Refer to image at the bottom.

2) I cracked two of the spark plugs, and some of the ceramic dust & pieces were stuck in the spark plug slot. I was able to vacuum what I could see, but not sure if they got into the cylinders. How big of a deal would this be if some indeed got into the cylinders? Anyone else have a similar experience?

3) Follow-up to 2), why would they break? I'm assuming they got brittle over time, but 5k mi/6mo isn't much... I also checked the gaps on all 6, and none were consistent, so I imagine I did a pretty terrible job gapping them. I used a coin to gap and bought feeler gauges this time around for my next set of spark plugs. Could that be causing the issue?
Also, I'm using a swivel joint to torque down the plugs to 23Nm, and I know using a swivel joint isn't the most accurate when torquing to spec. Could this also be a factor? How do others get around this?

Image below for the black residue referenced earlier:
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      04-04-2020, 05:44 PM   #2
Eschmacher
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Where did you get your plugs? There are a lot of counterfeit spark plugs out there, especially NGK.
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      04-04-2020, 08:23 PM   #3
pw0n
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Quote:
Originally Posted by Eschmacher View Post
Where did you get your plugs? There are a lot of counterfeit spark plugs out there, especially NGK.
Geez, are you serious? I bought them off FCP Euro - I'll post some pics soon.
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      04-04-2020, 10:08 PM   #4
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I would usually trust FCP euro. However I just had a bad experience with some Delphi coilpacks they sold me, so who's to say.
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      04-04-2020, 11:05 PM   #5
pw0n
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I can't comment on the authenticity of the plugs as I'm not sure, but I've posted the pics below. I'm going to have to post them separately as I don't know how to manage attachments on this forum.

Also, my fuel rails seem rusty/corroded (see pictures below) - anyone know if this is normal?
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      04-04-2020, 11:07 PM   #6
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Cylinder 1 images:
1. Closeup of tip
2. Coil pack
3. Spark plug slot
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      04-04-2020, 11:09 PM   #7
pw0n
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Cylinder 2 images:
1. Closeup of tip
2. Coil pack
3. Coil pack closeup (has some white specks)
4. Spark plug slot
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      04-04-2020, 11:09 PM   #8
pw0n
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Cylinder 3 images:
1. Closeup of tip
2. Coil pack
3. Coil pack closeup (orange/brown tint)
4. Spark plug slot
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      04-04-2020, 11:10 PM   #9
pw0n
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Cylinder 4 images:
1. Closeup of tip
2. Coil pack
3. Spark plug slot
4. Spark plug slot closeup
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      04-04-2020, 11:11 PM   #10
pw0n
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Cylinder 5 images:
1. Closeup of tip
2. Coil pack
3. Spark plug slot
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      04-04-2020, 11:12 PM   #11
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Cylinder 6 images:
1. Closeup of tip
2. Coil pack
3. Spark plug slot
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      04-05-2020, 10:42 AM   #12
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How did you crack the plug? The picture show legit NGKs to me. I would replace the browned coilpack. You didn't need to replace all 6 for hesitation.
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      04-05-2020, 12:37 PM   #13
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I was watching a N55 sparkplug DIY video (i think from FCP) the other day and they said there is a TSB out for the N55 that says the discoloration/rust color on the coil packs is acceptable and does not indicate a problem.
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      04-05-2020, 12:42 PM   #14
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Yeah, I would not think the discoloration would mean anything. also, my fuel rail looks like that too. wouldn't worry about it.

your plugs do look legit. I have no clue why they cracked though.
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      04-05-2020, 12:49 PM   #15
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FCP Euro would never knowingly sell counterfeit plugs. It's not worth the hassle.

What kind of swivel? A swivel for plugs won't throw off the torque all that much if it's attached at the thin walled socket. Now if you're using two extensionsn with a swivel in between then ya, torque will be off.

It's possible that your TQ wrench is off and the plugs were over torqued. This is the most common reason why plugs crack.


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      04-05-2020, 01:30 PM   #16
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I get 97506 from fcpeuro. No issues.
You were running too much gap for stock coils.
.022" is generally recommended for stock coils.
If you're running OEM Delphi coils (not BMW), get rid of them. They're junk.
Get either Eldor or BMW branded Delphi coils.
Make sure the mating surface on the cylinder head is squeaky clean.
Make sure you use an accurate torque wrench and a proper magnetic socket for bmw.
I recommend BMS.
I once had a plug come loose and leak oil when I torqued it to 23nm. I cleaned the surface throughly and torqued everything to 24.5nm.
Never had any issues since then.
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      04-05-2020, 10:25 PM   #17
pw0n
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Thanks guys - will gap my new plugs to 0.022". Also, decided to check my torque wrench, and it seems to be a bit off. Used a 15lb dumb bell to check the calibration

That said, I don't think I overtorqued - if anything I undertorqued the plugs.

Also, got my borescope today and checked the heads - one of them still has a noticeable amount of ceramic shards. Tried using a straw and a vacuum, but no luck. Anyone else have better ideas?
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