[NCM2C]

delete

[Track/S]

Stock plugs or 1step colder ones?
Plugs mileage?

I had a similar case, we changed the piston and 4 valves for safety.

[NCM2C]

Plugs were brand new - .020 gap.

basically they're saying if the cylinder wall is fine & pressure/leak down passes i'll go that route. but if it fails i'm looking at a Carbahn motor. FML

[Track/S]

Originally Posted by NCM2C

Plugs were brand new - .020 gap.

But oem ones or ngk iridium?

[chmura]

Could be leaky injector.

[NCM2C]

Cylinder 4 reading 20 PSI. Welp

[Simon P.]

Most likely a valve/valve seat from the plug ceramic bit getting caught there... bad luck. Time to start looking for a shop to rebuild it better than before!

[F87source]

For spark ignition to cause damage to the cylinder damage is if the ignition was premature enough to be super knock.

You can check if the cylinder is ok by doing a compression and leak down test.


Edit - I just read you posted that the cylinder read 20 psi, yeah the engine is going to need to be rebuilt.

[NCM2C]

Originally Posted by F87source

For spark ignition to cause damage to the cylinder damage is if the ignition was premature enough to be super knock.

You can check if the cylinder is ok by doing a compression and leak down test.


Edit - I just read you posted that the cylinder read 20 psi, yeah the engine is going to need to be rebuilt.

how could this happen? bad tune? bad fuel? mix of the two?

[F87source]

Originally Posted by NCM2C

how could this happen? bad tune? bad fuel? mix of the two?

I have no idea, but the list of why it happened could be extensive. It could be a bad tune, bad fuel, stuck injector, etc. I'm not really sure.

[Track/S]

Originally Posted by NCM2C

how could this happen? bad tune? bad fuel? mix of the two?

I asked you twice what spark plugs do you have, oem or 1step colder?

[NCM2C]

.020

[chris719]

Originally Posted by NCM2C

.020

Bosch? NGK? That's just a gap...

[NCM2C]

i am unsure on the brand, apologies - honestly processing what to do next trumped the brand / i trusted the mechanic's judgement on brand.

[F87source]

I doubt the brand nor gap would cause anything capable of blowing a cylinder. The worst it could be would be minor misfires, nothing like super knock - which would be needed to a blow a cylinder.

[Track/S]

Originally Posted by F87source

I doubt the brand nor gap would cause anything capable of blowing a cylinder. The worst it could be would be minor misfires, nothing like super knock - which would be needed to a blow a cylinder.

I would never use OEM spark plugs with stage1/2/3.
I have seen broken spark plug with stage1.

[chris719]

Originally Posted by Track/S

I would never use OEM spark plugs with stage1/2/3.
I have seen broken spark plug with stage1.

Cause or effect?

It seems like most misfire problems we see here are people using NGKs on Stage 1 and go away with stock plugs.

[Track/S]

Originally Posted by chris719

Cause or effect?

It seems like most misfire problems we see here are people using NGKs on Stage 1 and go away with stock plugs.

High EGT & EMP, these 2 things stress the plugs.

The exhaust wheels of the turbos are very small, for this reason the temperature and pressure increase with st1/2.

[F87source]

Originally Posted by Track/S

I would never use OEM spark plugs with stage1/2/3.
I have seen broken spark plug with stage1.

And what is the reason why you would never use the oem plugs with stage 1/2/3?

Because there is no factual evidence whatsoever to say these plugs aren't good up to those power levels and beyond. GTR's use the same heat range plugs as the OEM bosch plugs up to 700 whp without issue - so it's not a heat range issue. In fact the stock heat range is perfectly fine for up to 700 whp, there is no sense in going colder for no reason. Also, the M4 gts which makes stage 1/2 power levels stock uses the oem Bosch plugs without issue. So it's not Bosch. Unless the plugs show signs of running too hot - then it is irrelevant to think the bump in EGT's caused this.


In terms of the plugs being broken and cracking, that was common with the first generation ZR5TPP339 bosch plugs, BMW and Bosch has known this to be an issue so those plugs are both discontinued and recalled. The new ZR5TPP330A and ZR5TPP330 plugs are not proned to having this issue.

Here is the TSB: https://static.nhtsa.gov/odi/tsbs/20...48022-9999.pdf



Also there are many reasons why a plug could be broken, for instance if you don't use a wobble bit on the spark plug socket you can put massive amounts of stress on the plug body and cause it to crack. There are so many factors into why a plug can crack, so you can't just say stock plugs are garbage.

For isntance I too can say I have seen the NGK plugs crack: https://f30.bimmerpost.com/forums/sh....php?t=1708961

and this means a whole lot of nothing, because we don't know if it was user install error.


Until we see a trend of plugs breaking each and every time a certain power level is achieved - we cannot conclude that the spark plug X cannot handle power levels X and beyond. This is backed up by the m4 gts making stage 1/2 power levels without issue on the stock Bosch plugs.

[Track/S]

Originally Posted by F87source

And what is the reason why you would never use the oem plugs with stage 1/2/3?

Because there is no factual evidence whatsoever to say these plugs aren't good up to those power levels and beyond. GTR's use the same heat range plugs as the OEM bosch plugs up to 700 whp without issue - so it's not a heat range issue. In fact the stock heat range is perfectly fine for up to 700 whp, there is no sense in going colder for no reason. Also, the M4 gts which makes stage 1/2 power levels stock uses the oem Bosch plugs without issue. So it's not Bosch. Unless the plugs show signs of running too hot - then it is irrelevant to think the bump in EGT's caused this.

M4 gts have same power of standart m4....
+40hp it is thanks to the water injection.


Ngk 1step colder:

M4 GT4
M235iR
M2CSR
M6 GT3

[F87source]

Originally Posted by Track/S

M4 gts have same power of standart m4....
+40hp it is thanks to the water injection.


Ngk 1step colder:

M4 GT4
M235iR
M2CSR
M6 GT3

1) IDK how you came to this conclusion but even your statement itself is a contradiction: "the M4 GTS has the same power as the standard M4, +40 HP is thanks to water injection". What does that even mean? Does it have the same power or not, you can't say it has the same power and then it has 40 more horse power right after, that makes little to no sense.


In reality the GTS doesn't make the same power as the m4, it makes way more and that is a concrete fact, is it thanks to water injection? Yet but the it is undeniable that the GTS makes more power. Next misconception water injection alone doesn't increase power... You can spray water into a stock m4 and if you don't make a single tuning change the car will adapt to the water injection (you technically don't need to tune if you are just spraying water, because the water itself should be fully atomized in the charge pipe thereby displacing air, and so the air being displaced is measureable by the o2 sensor and the car can adapt by default, this is how the car adapts when running in high humidity or during a rainy day - no tuning needed just make sure the meth kit is truly progressive i.e. aquamist) and it will make zero additional power. Adding water has nothing to do with increasing power, even adding methanol doesn't increase power... The key is knock supression.

Water injection decreases IAT's and cools the flame front and any hot spots in the cylinders thereby supressing knock. This lets the car push harder by adding more boost and ignition timing. This is seen in the GTS because it targets 21-22 psi of boost, vs. 17-18 psi of a stock m4. So you are completely wrong on your analysis of the situation in regards to the GTS.

So what can we conclude? The power level and cylinder pressure isn't the cause of failure - because the M4 GTS which makes more power and runs more boost is just fine. Is it EGT? Again there is no conclusive evidence that Stage 1/2 (with a tune that isn't lean) over heats these plugs - if you're melting plugs you're melting pistons right after, so EGT isn't an issue either. I have seen so many images of the stock bosch plugs after tuning and they look fine. None of them were glazed over due to running hot. Is it "EMP", and by EMP I assume you mean eddy currents and electrical noise, I highly doubt this is the case because the IGBT in the Ecu and the coil packs would be toast if this was the case long before the spark plugs were.

So you haven't given any concrete evidence to counter this, you're just giving opinions that don't even seem to be common enough to be credible. This is just like when you said oil has no link to carbon build up with zero concrete evidence, except your own limitied visual observations that have no scientific merit. Then you try to draw major conclusions off a small and limited sample size and refused to accept scientific studies done by countless others that do link carbon build up directly to to the oil and NOACK/SAPS ratings.


2) There are 2 part numbers for spark plugs on the m235ir, one of them is Bosch: https://www.realoem.com/bmw/enUS/sho...diagId=12_1926

The GT3 and GT4 cars do use NGK's, but these are motorsports cars under race conditions - which may justify the requirement of a colder plug. Because I doubt the NGK's are "tougher" because I've seen them crack and fail too. Or NGK could be a parts sponsor, since they sponsor alot of motorsports cars - they sponsor ferrari in F1 for example.


So there still isn't definitive evidence that the stock plugs will crack or fail when tuned
over stock power levels on a street car. What you claimed is that the stock plugs couldn't handle the power bump and would fail, and you still provided no definitive evidence. You said that you've seen stock plugs crack, well I too have seen NGK's crack - what's your point? You literally can't draw any conclusion based off of such a limited data set. This cracking could be user install error, or another issue like very agressive knock that broke the plug. In either case it just doesn't make sense to blame it on the plug. Plug's don't just break by themselves, so there must have been another root cause.








Either way OP's engine is blown. So there isn't much left to say except hope that it isn't catastrophic and limited to just piston damage.

[chris719]

Originally Posted by Track/S

M4 gts have same power of standart m4....
+40hp it is thanks to the water injection.


Ngk 1step colder:

M4 GT4
M235iR
M2CSR
M6 GT3

What gap do you run typically for stage 1?