Plug/coil failure while on track

[Mortis]

Hi everyone,

I was at VIR this past weekend and in the middle of a track session under hard acceleration when I got a drivetrain error and went into limp mode. The awesome techs there read the codes and diagnosed this as plug / coil failures (subsequently confirmed by my BMW dealership). These were due for replacement so no surprise (will get all six plugs/coils replaced) but I'm curious to know whether I should aim to replace them more often given that I plan on tracking the car fairly heavily over the course of the year (6-7 HPDEs). Does track use shorten their life spans? Should I be looking at specific brands (my car is stock, no tunes or engine mods)? Apologies in advance for the noob questions.

All best.

[SYT_Shadow]

I haven't heard of premature coil/plug wear, especially on stock engines.

I would keep the engine stock for max reliability, good move

I'm doing +30 days, double tracking the CS and have zero issues. Incredible reliability so far

[robbo mcs]

Originally Posted by Mortis

Hi everyone,

I was at VIR this past weekend and in the middle of a track session under hard acceleration when I got a drivetrain error and went into limp mode. The awesome techs there read the codes and diagnosed this as plug / coil failures (subsequently confirmed by my BMW dealership). These were due for replacement so no surprise (will get all six plugs/coils replaced) but I'm curious to know whether I should aim to replace them more often given that I plan on tracking the car fairly heavily over the course of the year (6-7 HPDEs). Does track use shorten their life spans? Should I be looking at specific brands (my car is stock, no tunes or engine mods)? Apologies in advance for the noob questions.

All best.

Coil failures are actually rare.
Plugs do take a hammering on the track, especially in modified engines.

With your scenario you really need to have a look at the plug, and see what has happened. There are many ways a plug can fail. If for example the end has literally melted off and disappeared, then that is not good.

The thing is, a BMW dealership will just pull them out and throw them in the bin, without a second thought, and put new ones in. Let them know you want the old plugs (and coils if replaced) to examine, and also ask them to number them. Then get a race shop or someone who knows what they are doing to have a look. That way you will get a better idea if this is just a freak failure, or something you need to pay more attention to.

In the end, plugs are relatively cheap, compared to the cost of an engine rebuild etc. So think of it like an oil change, if you are tracking a lot, then you definitely should be doing more frequently than normal intervals. If you are tracking a lot, you should pull the plugs every now and then and have a look, and see how they are going. That will let you choose how often to replace them

[khcoaching]

I just had this happen a few weeks ago on a clients 2018 M3c, 16k miles. The car has a completely stock drivetrain (no flash, etc) and the dealer was happy to warranty it. Though....they only replaced the 1 coil and 1 plug. (Owner had the rest done as preventative) It was recommended to remove the upper engine cover and sound deadening material for more airflow, as well as getting the hood open after a run. (Which we already were doing)

The shop race shop we deal with for suspension recommend replacing plugs and coils once a year on this car as it sees 25+ days a year on the track.

Ken

[gum2012]

This happened to me on my F82. BMW recommends changing plugs every 40k miles I believe. However with a tune you should do it every 20k because they get hammered on track. I also change my coils with plugs every 10k.

BMW recommends changing them every 5k miles on my m2csr. If you track your m4 regularly you should use the same maintenance schedule as an m4 gt4. It's the same engine and components so that's a good barometer on what to use. But you are actually pushing it harder I believe since the gt4 is using 430 HP with no tune up.

[F80Speed77]

What plugs are recommended for the S55?

[Mortis]

Thanks everyone - great comments and advice here. My dealer also only wanted to replace one plug and coil, and charge me US$1,500 to boot (!) as this is apparently not covered under CPO warranty. So much for dealership customer retention. I bought the plugs/coils myself and asked my local shop to do the install. Conventional wisdom seems to be stick with OEM plugs for stock, NGK iridium for tuned engines.

[NYG]

Coils last over 100k mi, it's probably preventative maintenance that's being done as a secondary for plug failure. I'm guessing your code was excessive misfires and the car went limp to prevent catalytic convertor damage?

Plugs do not require constant replacement but because the S55 is direct injected, they will get CAKED way faster than with port injection. Regardless, change them and don't think about them for another few years. If the air/fuel mixture fails to combust, that's not going to hurt your engine. If you had preignition then that would be far more of a concern but assuming you have a stock tune (rich factory mixture) I highly doubt that you were getting preignition.

[NYG]

On another note to add above, I personally would replace/clean valves every 2-3 years with direct injected engines. Driving your car hard will actually reduce that fouling in the cylinder a little bit(plug) but your valves are inherently going to get fouled with DI engines.

[fanatic1]

tom @ eas


Maybe Tom or Kevin can weigh in, but heard of many coil pack replacements. May be only on tuned cars, but definitely heard of replacements.

Spark plugs replaced twice om 19 M4 in 30,000 miles, once by dealer and once by EAS.

[Mortis]

Thank you - great advice. I was getting combustion misfire and combustion period too short across several cylinders.

Originally Posted by NYG

Coils last over 100k mi, it's probably preventative maintenance that's being done as a secondary for plug failure. I'm guessing your code was excessive misfires and the car went limp to prevent catalytic convertor damage?

Plugs do not require constant replacement but because the S55 is direct injected, they will get CAKED way faster than with port injection. Regardless, change them and don't think about them for another few years. If the air/fuel mixture fails to combust, that's not going to hurt your engine. If you had preignition then that would be far more of a concern but assuming you have a stock tune (rich factory mixture) I highly doubt that you were getting preignition.

[NYG]

Originally Posted by Mortis

Thank you - great advice. I was getting combustion misfire and combustion period too short across several cylinders.

If it was across several cylinders then it's possible the coilpack did actually fail.

But yeah, don't worry - you probably had a code "damaging exhaust gas" as well. So your engine went limp to protect your catalytic convertor. The serious codes include "detonation," "knock sensor," "camshaft timing," "crankshaft timing," etc..

The word "damage" makes it seem more serious than it is. So many kids run flamethrower tunes which literally does what your engine did as a result of a failure. The life span of the cat gets shortened but calling it damage is a stretch.

[melanthius]

Originally Posted by SYT_Shadow

I haven't heard of premature coil/plug wear, especially on stock engines.

I would keep the engine stock for max reliability, good move

I'm doing +30 days, double tracking the CS and have zero issues. Incredible reliability so far

I had coil failure that trashed several set of plugs. Totally stock and occurred before 50k miles without any track time (occurred on my way to the damn track). Although I am the second owner so who knows.

At first I didn't know it was the coils, so I changed plugs, then got drivetrain malfunction/limp mode again, started getting paranoid that the plug install was bad, so I had them swapped again, rinse, repeat, etc.

Smart thing to do is definitely swap coils and plugs at the same time when this crap happens.

[Spun Crankhub]

I do preventive on coils and plugs yearly, irrespective of mileage. Is it possibly overkill? Probably, but years ago had an N54 that went through them so often, that I've made it a habit.

[Mortis]

Originally Posted by NYG

If it was across several cylinders then it's possible the coilpack did actually fail.

But yeah, don't worry - you probably had a code "damaging exhaust gas" as well. So your engine went limp to protect your catalytic convertor. The serious codes include "detonation," "knock sensor," "camshaft timing," "crankshaft timing," etc..

The word "damage" makes it seem more serious than it is. So many kids run flamethrower tunes which literally does what your engine did as a result of a failure. The life span of the cat gets shortened but calling it damage is a stretch.

My local shop did the swap today - all six plugs and coils. Both plugs and coils were on their last legs - can't believe dealer only wanted to replace one. Car feels great and if I'm not mistaken I've also gotten some power back … good advice from all here - will check plugs/coils periodically and replace way before recommended date.

[tom @ eas]

Originally Posted by fanatic1

tom @ eas


Maybe Tom or Kevin can weigh in, but heard of many coil pack replacements. May be only on tuned cars, but definitely heard of replacements.

Spark plugs replaced twice om 19 M4 in 30,000 miles, once by dealer and once by EAS.

Coil failure is rare on street cars, but ignition components take a beating with those running higher boost/extended sessions. Replacement will be much more common in that scenario.

[chriskeefe]

I had this exact scenario at VIR of all places haha. If your misfire was on cylinder 4,5 or 6 check your low temp circuit (intercooler) reservoir. If its low, your intercooler could be leaking into your throttle body causing misfires by getting cylinders 4,5 & 6 wet. I chased this for a hot minute being in green run groups at the time not being allowed to bring a logger in the car. I kept blanketing the issue with plugs and coil packs till I logged my IAT's and realized something was up. Other than that you shouldn't have any issues with coil packs / plugs on a stock low mile S55.

[TopJimmy]

Only use OEM Delphi coils, they're good to 100K unless one fails sooner (track use could do it). I hear they're good up to 1K HP.

The iP and BavAuto coils for S55 are junk... Had em. Junk.

Plugs should be OEMs for up-to Stage1, gapped to .023in.
If running Stage 2 or above you should use NGKs gapped .021in.

[BetrayMyWord]

On my second sets of coil now.

Cars has had three times of CELs at the first year of ownership (it's bought new), and every time my dealer only replaced a single spark plug

[melanthius]

Originally Posted by BetrayMyWord

On my second sets of coil now.

Cars has had three times of CELs at the first year of ownership (it's bought new), and every time my dealer only replaced a single spark plug

This is what the bastards always do.

This is the problem with extended warranties as well. Oh you have misfire? Well let's just change 1 part. Another misfire? change 1 part again. Third misfire? OK this time we'll opt to change 1 part again.

Take it from me - any sane person should absolutely change all coils and plugs if this happens, and be done with it. It is the only way to remain sane.

Forget the warranty, just get it done right.