How does this spark plug look?

Tangent · 08-09-2018, 10:48 PM

I'm chasing the cause of misfires after replacing one confirmed bad coil and could use a more experienced eye on judging the condition of this plug.

IllSic_Design · 08-09-2018, 10:53 PM

Change it/all of them

WeekendWarriorz · 08-10-2018, 12:09 AM

Quote:

Originally Posted by IllSic_Design

Change it/all of them

+1!!!! Change them that one doesn't look good!

tmick5jr · 08-10-2018, 05:48 AM

i wish i was that rich

08-10-2018, 07:03 AM

Neglected

Tangent · 08-10-2018, 09:33 AM

Quote:

Originally Posted by FCobra94

Neglected

In what way?

Bimmer_Engineer · 08-10-2018, 10:34 AM

How long was it in there for?

Tangent · 08-10-2018, 11:11 AM

Quote:

Originally Posted by Bimmer_Engineer

How long was it in there for?

About 10,000 miles. There have been a couple of track days and a bunch of autocross in there so it's seen way more WOT time and higher temps than the typical street driven car but I didn't expect that to be quite this hard on the plugs...

langsbr · 08-10-2018, 11:56 AM

I'd switch to a different type of plug too.

catcher22 · 08-10-2018, 12:01 PM

Hold that up to a new plug and you'll clearly see the difference. Just use some common sense man, that plug looks incredibly bad.

King Rudi · 08-10-2018, 12:51 PM

Quote:

Originally Posted by Tangent

In what way?

That plug is gently used at worst.

I'm obviously joking.

Yeah man, that thing is in bad shape. If you are chasing misfires, seems like you might be on the right track. Question. If you aren't sure this plug is bad, how did you confirm that you had at least one bad coil?

arkie6 · 08-10-2018, 02:35 PM

That plug is worn out. The sharp edges on the center and ground electrodes are gone. Just look at the difference compared to a new plug below. The sharp edges concentrate the electric field and reduce the voltage needed to jump the gap (kinda like a lightening rod). Those worn away rounded edges require higher voltages to initiate the spark which puts additional strain on coil's electrical insulation. If all of your plugs look like that in only 10,000 miles, I would replace them with a different spark plug designed for higher boost / HP applications, i.e. NGK 95770 gapped to 0.022". I would also replace all of the ignition coils.

Tangent · 08-10-2018, 02:58 PM

Quote:

Originally Posted by Not_Judy

That plug is gently used at worst.

I'm obviously joking.

Yeah man, that thing is in bad shape. If you are chasing misfires, seems like you might be on the right track. Question. If you aren't sure this plug is bad, how did you confirm that you had at least one bad coil?

Swapped coil location and the misfire followed it. It was a couple of days after installing 6 new coils that I got a misfire on a different cylinder. I was in a hurry at the time so I took a shot in the dark that it was a bad coil out of the box and swapped one of the working old ones back on and it was fine for several more days until it came back. It didn't occur to me that the plugs would be cooked after 10k miles already without way more power than I've got.

I've never had a turbo engined car before this one so I'm used to seeing pretty crusty looking plugs get swapped out just based on mileage and having no driveability changes. I've also never bothered to take a picture that zoomed in on it like this. I mean obviously it looks like it's been living in a combustion chamber for a while; I just had no basis of comparison for "used but okay" vs "how is that still generating a spark".

Tangent · 08-10-2018, 03:01 PM

Also can anyone tell me if just extended hard driving like on track days calls for a colder plug even if based on mods alone you shouldn't otherwise need that? I've only got a stage 1 MHD tune which I've never seen anyone suggest different plugs for.

335e92tx · 08-10-2018, 03:31 PM

Quote:

Originally Posted by Tangent

Also can anyone tell me if just extended hard driving like on track days calls for a colder plug even if based on mods alone you shouldn't otherwise need that? I've only got a stage 1 MHD tune which I've never seen anyone suggest different plugs for.

No probably not but that ant good. So none of the others look like that?
It looks like ash more than anything. Which is kinda perplexing.

Move the coil or get a new coil for that hole.

Tangent · 08-10-2018, 05:42 PM

Quote:

Originally Posted by 335e92tx

No probably not but that ant good. So none of the others look like that?
It looks like ash more than anything. Which is kinda perplexing.

Move the coil or get a new coil for that hole.

I'm kind of suspecting the ash is the result of the burble setting in MHD. It's only set to moderate for 5 seconds but it is running rich by design when it's doing that... I haven't pulled the rest of the plugs yet; I just pulled that one out real quick last night; I'm just going to replace them all in the next couple of days.

08-09-2018, 10:48 PM	#1
Tangent Lieutenant 298 Rep 584 Posts Drives: G01, F82, E89, F25 Join Date: Jun 2015 Location: California iTrader: (2)	How does this spark plug look? I'm chasing the cause of misfires after replacing one confirmed bad coil and could use a more experienced eye on judging the condition of this plug. Attached Images
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08-09-2018, 10:53 PM	#2
IllSic_Design Colonel 2124 Rep 2,758 Posts Drives: 09 E92 335i Join Date: Jun 2016 Location: Northern California iTrader: (1)	Change it/all of them
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08-10-2018, 05:48 AM	#4
tmick5jr Second Lieutenant 84 Rep 244 Posts Drives: 335i Join Date: Jul 2016 Location: Jersey iTrader: (0)	i wish i was that rich
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08-10-2018, 07:03 AM	#5
FCobra94 Guest 0 Rep n/a Posts Drives:	Neglected
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08-10-2018, 10:34 AM	#7
Bimmer_Engineer Lieutenant Colonel 1044 Rep 1,667 Posts Drives: 2007 335i Join Date: May 2018 Location: Louisiana iTrader: (0) Garage List 2008 Porsche Boxster [0.00] 2016 Mercedes Benz ... [0.00] 2007 BMW 335i [9.50]	How long was it in there for?
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08-10-2018, 11:56 AM	#9
langsbr First Lieutenant 234 Rep 317 Posts Drives: 335i Join Date: Aug 2013 Location: SC iTrader: (0)	I'd switch to a different type of plug too.
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08-10-2018, 12:01 PM	#10
catcher22 Captain 294 Rep 922 Posts Drives: 2008 335xi Coupe Join Date: May 2008 Location: Virginia iTrader: (2)	Hold that up to a new plug and you'll clearly see the difference. Just use some common sense man, that plug looks incredibly bad.
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08-10-2018, 02:35 PM	#12
arkie6 Lieutenant 397 Rep 433 Posts Drives: 2008 BMW 335i sedan Join Date: Aug 2014 Location: Russellville, AR iTrader: (0) Garage List 2008 BMW 335i [0.00]	That plug is worn out. The sharp edges on the center and ground electrodes are gone. Just look at the difference compared to a new plug below. The sharp edges concentrate the electric field and reduce the voltage needed to jump the gap (kinda like a lightening rod). Those worn away rounded edges require higher voltages to initiate the spark which puts additional strain on coil's electrical insulation. If all of your plugs look like that in only 10,000 miles, I would replace them with a different spark plug designed for higher boost / HP applications, i.e. NGK 95770 gapped to 0.022". I would also replace all of the ignition coils. Attached Images
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08-10-2018, 03:01 PM	#14
Tangent Lieutenant 298 Rep 584 Posts Drives: G01, F82, E89, F25 Join Date: Jun 2015 Location: California iTrader: (2)	Also can anyone tell me if just extended hard driving like on track days calls for a colder plug even if based on mods alone you shouldn't otherwise need that? I've only got a stage 1 MHD tune which I've never seen anyone suggest different plugs for.
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