[fe7565]

2012 F30 N26 - ignition coils 113K miles, spark plugs 50K miles

Is the ignition coil an either "works" or "does not work" item like a TV, etc?

As a I understand that ignition coils do lose some effectiveness with use, maybe 10% or so. But is that a reason to replace them after a certain amount of miles? Or wait until one fails and then replace all of them? If preventive is the reason...then at what mileage?

[StradaRedlands]

I'm not sure what the "right" thing to do is, but I replace when misfires start showing up. Then I replace all six as they're the same age and I only have to get the cowl pulled off one time. I do plugs at the same time on principle.

[Emily172013]

I had coil go bad on a Nissan Maxima while on vacation years ago. I bought a new one at a auto parts store and played musical chairs switching them out until the bad one appeared.
Probably went 50k after that with none of the others going bad.

[DanG]

If I remember correctly sparks plugs are recommended to be changed every 32,000 miles.

[RockCrusher]

Originally Posted by fe7565

2012 F30 N26 - ignition coils 113K miles, spark plugs 50K miles

Is the ignition coil an either "works" or "does not work" item like a TV, etc?

As a I understand that ignition coils do lose some effectiveness with use, maybe 10% or so. But is that a reason to replace them after a certain amount of miles? Or wait until one fails and then replace all of them? If preventive is the reason...then at what mileage?

The short answer is maybe.

While one can wait for a coil to go bad to the point misfires occur the coil or coils could under perform staying below the misfire threshold for some time.

I've never had any coils go bad in ~1M of driving (various cars).

But at 132K miles my 2003 996 Turbo manifested a CEL with an O2 sensor code. A heating element was bad. The engine manifested no untoward behavior. In fact the CEL came on at a gas station in Barstow CA and I drove the car from Barstow to Livermore CA with no problems.

Once home I booked the car in for new O2 sensors. After new O2 sensors installed the engine ran better. This surprised me. The engine had not felt down on power or pep but the improvement was real.

At around 140K miles on a whim I decided to have the coils replaced. No CEL.No signs of any issues with the coils. Just on a whim. And some curiosity based on the results of new O2 sensors. Would new coils have any positive effect on the engine?

Tech advised me since the plugs were about 10K miles from their change by miles he recommended changing the plugs while he was there. I agreed.

After new coils -- which were the new improved coils from the 997 -- and new plugs the engine ran better. As was the case after installing new O2 sensors this surprised me.

I attributed this improvement to the coils. I had had the plugs changed several times before this and the engine never reacted one way or the other to the presence of new plugs.

Sure the replacement coils were the new/improved coils from the newer model line. No way to know if new 996 coils would have had the same effect.

While I'm an advocate of if it ain't broke don't fix it based on my experience described above I could be tempted to replace coils (even O2 sensors) *before* they deteriorate enough to manifest any signs of this deterioration. I don't know at what mileage but safe to say at ~100K miles I'd be more on board with coil replacement than I would be at 50K miles.

(As an aside while no coils have gone bad with several of my cars O2 sensors have gone bad anywhere from 80K to 130K miles.)

I can't bring myself to say outright you should replace the coils, hence the "maybe"...

The above assumes the factory doesn't have coils or O2 sensors replacement on its service schedule. If it does then of course barring a premature problem go by the schedule.

[fe7565]

Thank you and thanks for the comments from others as well. I already bought the parts, (coils and spark plugs) about a year ago in anticipation of any issues popping up, And the spark plugs have over 50,000 miles so might as well replace the coils as well.

The car is running great, so it seems a bit wasteful to make these replacements, Specially, in light that I haven’t decided yet if I’m going to keep the car for more than a couple of more years. At the same time, I don’t think a future owner would care to consider in the selling price a bunch of brand new spare parts on the side. So may as well do the replacement so the car in that aspect is good for another 60k to 80k miles.

[jefe2000]

Originally Posted by DanG

If I remember correctly sparks plugs are recommended to be changed every 32,000 miles.

That’s true for the N55’s in our M2’s, Dan. But for many of BMW’s non-///M gasoline engines, the spark plug interval is usually specified at every 5th oil change. With the factory 10K mile oil change interval (in the USA), that works out to swapping the plugs every 50K miles.

[DanG]

Originally Posted by jefe2000

That’s true for the N55’s in our M2’s, Dan. But for many of BMW’s non-///M gasoline engines, the spark plug interval is usually specified at every 5th oil change. With the factory 10K mile oil change interval (in the USA), that works out to swapping the plugs every 50K miles.

I was just reading that the spark plug interval for non M engines was every 30,000 to 50,000 miles.

[jefe2000]

Some good advice here on plugs and coils for the N20 and N26 engines. Fast forward to the 6m29s mark.
https://www.youtube.com/watch?v=NV1LWDeMw38&t=389s

[fe7565]

Originally Posted by jefe2000

Some good advice here on plugs and coils for the N20 and N26 engines. Fast forward to the 6m29s mark.
https://www.youtube.com/watch?v=NV1LWDeMw38&t=389s

Great video! Just watched it all. Somehow I missed this one from FCP Euro.

[fe7565]

Originally Posted by DanG

I was just reading that the spark plug interval for non M engines was every 30,000 to 50,000 miles.

FCP Euro says manufacturer (NGK) claims 100K miles, but they recommend a more reasonable 50K. N20/N26

[fe7565]

I did today the oil filter housing gasket and the oil cooler gasket. Planning to do the spark plugs and coils next. I know they supposed to come pre-gapped, but I always check. I was reading in various forums and FCP Euro about the required gapping for the N26 stock engine.

NGK specifies for OE 0.032” for the N26. I have the SILZKBR8D8S 97506. Any differing recommendations?

Also, I believe silicone grease is not allowed?! I wanted to use it so the spark plug slides in easier into that special thin-wall spark plug socket’s rubber lining. it seems to be an awfully tight fit.

[Jolbex]

Rubber lining? If you refer to coils only talk (talc?) is allowed as lubricator

[fe7565]

Originally Posted by Jolbex

Rubber lining? If you refer to coils only talk (talc?) is allowed as lubricator

My spark plug socket has a rubber lining inside and the plug’s ceramic portion slides into it so it can grab the plug while inserting into the engine block. But it’s a pain to force the plug into it and afraid that the ceramic may crack.

The new coils supposed to have dielectric grease, so FCP Euro says not to use dielectric grease because it could add up to be too much.

[RockCrusher]

Originally Posted by fe7565

Thank you and thanks for the comments from others as well. I already bought the parts, (coils and spark plugs) about a year ago in anticipation of any issues popping up, And the spark plugs have over 50,000 miles so might as well replace the coils as well.

The car is running great, so it seems a bit wasteful to make these replacements, Specially, in light that I haven’t decided yet if I’m going to keep the car for more than a couple of more years. At the same time, I don’t think a future owner would care to consider in the selling price a bunch of brand new spare parts on the side. So may as well do the replacement so the car in that aspect is good for another 60k to 80k miles.

I have had plugs replaced -- on the factory schedule -- a number of times with various cars.

At no time did the engine ever react favorably (or unfavorably) to the presence of new plugs.

To me this is a welcome behavior. The plugs were doing an adequate job until their change by date/miles.

The last thing I want to do is run plugs for so long the engine manifests any untoward behavior.

There is another consideration at least with some of my car engines. The factory called for plug changes at so many miles -- no surprise there -- or after so much time. A bit of a surprise, maybe.

But if one looks at old plugs -- I'll post a pic of some -- one can see the plug threads are discolored. This is from the slow creep of combustion by products being forced up the plug threads. These byproducts are corrosive.

There is the risk of upon removing the old plugs the corrosion results in further damage to the head threads.

Bad enough the plug threads get damaged but the head threads are in very expensive heads -- to state the obvious.

Just because the plugs are not manifesting any signs of age/deterioration does not mean they are not due to be replaced.

The plugs in the pic of from/for my 2002 Boxster. The used plug was removed -- along with the other 5 -- at 60K miles the mileage at which Porsche called for plug replacement. I don't recall if Porsche had a change by date for Boxster plugs. (It had a change by date for my 2003 996 Turbo.) I drove the Boxster a lot of miles per year -- on average 20K miles a year -- and plugs were changed every ~3 years.

I always used factory plugs. The factory plugs come with a *dry* thread treatment that helps ensure proper installation and accurate torque reading and yet doesn't result in any additional substance on the threads.

The risk is any thread lube can work to insulate the plug threads from the head threads and thus slow the flow of heat from the plug tip out through the threads of the plug to the threads of the head. The plug can run hotter which can shorten its useful life.

Some thread lubes (aluminum based IIRC) can be harmful to O2 sensors even catalytic converters.

[ctcarbonari]

+1 to RockCrusher posts above. I think he's given the best advice on this thread.

Here's my 2 cents:

Plugs every 30-50k miles (closer to 30k for tuned engines).
Coils every 90-100k miles (as PM).

NO DIELECTRIC GREASE.

The 14mm thinwall w/ swivel that I use is magnetic & has no rubber grommet on the inside.

Spark plug gap varies a slight bit; however, they come pre-gapped and it's usually pretty easy to find out what that number is so you can check before install.
For example, on my 15' 535i (F10) w/ N55 engine, the stock gap spec ranges from 0.028" to 0.032".

Bosch ZR5TPP33 are gapped @ ~0.030"
Genuine BMW (Bosch) ZR5TPP33S are gapped @ 0.028"
(and yes, there is a difference between those 2 plugs. It's in the internal resistance rating)

[fe7565]

Replaced the coils and spark plugs today. I checked and all four NGK’s were pre-gapped properly at 0.032 inch.

The replaced NGK plugs had about 50,000 miles… three out of the four were still at around 0.032 inches one of them was at .0035.

[ctcarbonari]

Originally Posted by fe7565

Replaced the coils and spark plugs today. I checked and all four NGK’s were pre-gapped properly at 0.032 inch.

The replaced NGK plugs had about 50,000 miles… three out of the four were still at around 0.032 inches one of them was at .0035.

Nice! Hope it all went smoothly for ya.

Now you have a set of "emergency spare coils"...