[Voomar]

Hey All,

After searching this forum, I thought a new thread on carbon build up in the N55 might be helpful. I'm curious if any of the early M2's have shown signs of carbon build up on the intake valves and fuel injectors. Also, what are people doing to reduce the build up, and what has been BMW's position on carbon build up on its other direct injection engines?

Background: My first experience with a DI engine has been an Audi 2.0 TFSI. Car was purchased new in 2012 and used as a daily driver in mixed city/highway commuting of about 40 miles per day. I followed all factory maintenance recommendations (performed by dealer) and have always used top tier rated fuel. Car has 55K miles and is stock tune other than a CAI. It recently started running poorly when cold and under mild engine loads. Of course the car is out of warranty when this started happening, so I took the car to a local and reputable VW/Audi tuner last week for some advice. I subsequently learned about carbon fouling likely being the culprit, and solution was a thorough cleaning of the intake valves, intake manifold and injectors with a walnut shell cleaning technique. I decided to pull the trigger on both a mild tune and the cleaning. Problem solved and nice power increase with the tune, albeit my wallet is lighter as a result. The tech also showed me pictures of the intake valves before the cleaning, so I saw the carbon build up first hand.

As one might expect, the walnut shell cleaning is pretty labor intensive at 6 hours total for an Audi/VW four-banger, and I can only imagine the labor tally for the same cleaning on the N55 in my 2018 LCI. No immediate concern for me on my other BMWs with S52 and M54 engines as both are non DI.

My limited research shows that carbon build-up is inherent in the design of any DI engine, so it's a matter of time before some type of cleaning is needed.
https://www.rennology.com/your-car/b...rbon-cleaning/

Some preventative measures for delaying the carbon build up include:

1. More frequent oil changes
2. Italian tune up each time the car is driven
3. Install Oil Catch Can on the intake (although I think this may void warranty and create issues with emissions testing.)

Please share thoughts and experiences on theses topics.

Cheers!

[impulsiv]

I have two VWs with 2.0T BPY engines, a 2008 GTI and a 2007 Passat, none of them has never had their valves cleaned. The GTI was bought new and babied all its life, and has seen oil changes every 5k km. It has now 145000km. The Passat is at 174000km (bought at 124000km) and also sees oil changes every 5 k km. As a VW master tech, i do beleive that frequent oil change with quality oil is a big part of the equation. But DI being what it is, cleaning will still be needed at a certain point.

[Aronis]

This is an interesting thread. I thought that the direct injection had a positive effect on minimizing carbon build up?

I had my RS6 engine apart at 140,000 miles and we looked at the cylinders, valve train, etc, and not a bit of carbon build up. I changed the oil every 10,000 miles as per recommendation of manufacture (used to change all my cars at 5,000 miles, kind of surprised your changing at 5k kilometers ? 3000 miles?) and drove that car they way it was meant to be driven. :0 (currently have current leak problem, and I have not found the fault yet.....friggen old cars......

What did the cleaning process entail? I remember my dad having it done on his M5 back in the 90's but that was covered by warrantee. Does much have to be taken apart to do it? Price?


Mike

[champignon]

The N54 engine was notorious for this, but supposedly the N55 has way less of this problem. Lots of carbon blasting stuff over on the 1-Series boards, but mostly related to the N54 versions, not the N55s.

[velociti]

Originally Posted by champignon

The N54 engine was notorious for this, but supposedly the N55 has way less of this problem. Lots of carbon blasting stuff over on the 1-Series boards, but mostly related to the N54 versions, not the N55s.

This. Every 40-50k miles seems to be the rule of thumb for the N54, and the pictures of the valves back this up. The N55 looks to be able to at least double that figure, and with less buildup to boot. Call it 90k or 100k.

[stefan]

I was going to say.. you must be coming from the Audi world. Not a problem on an N55. Though after 200,000mi I'd do it anyway.

[PackPride85]

Walnut blast service is about $500 these days. With the N55 you're maybe doing it roughly 50-70k miles if you want it to be super clean. If you don't keep your cars very long you'd be fine without it. If you plan to hold it until it dies, not a bad idea and not pricey considering you'll probably have spent $4k on tires by that mileage.

[Voomar]

Originally Posted by Aronis

This is an interesting thread. I thought that the direct injection had a positive effect on minimizing carbon build up?

I had my RS6 engine apart at 140,000 miles and we looked at the cylinders, valve train, etc, and not a bit of carbon build up. I changed the oil every 10,000 miles as per recommendation of manufacture (used to change all my cars at 5,000 miles, kind of surprised your changing at 5k kilometers ? 3000 miles?) and drove that car they way it was meant to be driven. :0 (currently have current leak problem, and I have not found the fault yet.....friggen old cars......

What did the cleaning process entail? I remember my dad having it done on his M5 back in the 90's but that was covered by warrantee. Does much have to be taken apart to do it? Price?


Mike

Actually a DI engine exacerbates the carbon build up on the intake valves because the fuel, being directly injected into the cylinder, does not have a chance to act as a natural solvent on the intake as is the case with port injection methods.

I followed the manufacturers recommended oil change interval which was 10K miles or 12 months with full synthetic oil. After going through this issue with the carbon build up on the 2.0 TFSI, I plan to change the oil at half the recommended interval...plan to do the same on the N55 as well.

The walnut cleaning is basically a sand blasting-like process whereby the media is finely ground walnut shells instead of sand...the former is less abrasive. The procedure requires the exhaust manifold and injectors be removed and blasted as well as the back of the intake valves. The service cost me about 900 USD and included new manifold gasket, injector service kit and the blasting media. Vast majority of the cost was the labor.

[Voomar]

Thanks. Good advise on the more frequent oil changes.

[bobert]

Originally Posted by Voomar

Thanks. Good advise on the more frequent oil changes.

This debate comes up on a regular basis - here's a couple threads if interested:

http://f87.bimmerpost.com/forums/sho....php?t=1437482

http://f87.bimmerpost.com/forums/sho....php?t=1407263

[Aronis]

If I keep this car long term it will be with an extended warrantee. LOL.

Mike

[DSTR]

Originally Posted by Voomar

Thanks. Good advise on the more frequent oil changes.

Not an oil change issue.

[skiparock]

Had an 2011 335 and checked around 70k, no issues or need for walnut blast

[DSTR]

My dealer and primary mechanic are not at all seeing a major 'issue' with carbon deposits requiring service so far. BMW has done a nice job with the motor in that situation it appears.

[F87_LCI]

"Italian tune up" Admittedly never heard this term before...had to Google - An Italian tuneup usually refers to a process whereby a motor vehicle engine is run at full load for extended periods in order to burn carbon buildup from the combustion chambers, spark plugs, and exhaust system.

So...basic daily driving then.

[pruettfan]

Originally Posted by Aronis

If I keep this car long term it will be with an extended warrantee. LOL.

Mike

Warranty won't cover carbon build up. The N54 guys all had to pay or DIY their cleanings.

I did a substantial amount of searching on this topic prior to ordering my M2 because this issue was significant in the N54, I found no evidence that this is a problem on the N55.

[Aronis]

I hope to be driving an AWD M5 by the time my M2 has a carbon build up issue.

Mike

[TMR013]

I had the valves walnut blasted at 80K on my N54 135. Made a huge difference, should have done it sooner, engine felt like new again. Anybody know what the difference is in the N55 that would make this less prevalent?

[DrivingPassion]

Originally Posted by F87_LCI

"Italian tune up" Admittedly never heard this term before...had to Google - An Italian tuneup usually refers to a process whereby a motor vehicle engine is run at full load for extended periods in order to burn carbon buildup from the combustion chambers, spark plugs, and exhaust system.

So...basic daily driving then.

Here's a vid on Italian TuneUp and whether it works or not:

[M Fifty]

Originally Posted by TMR013

I had the valves walnut blasted at 80K on my N54 135. Made a huge difference, should have done it sooner, engine felt like new again. Anybody know what the difference is in the N55 that would make this less prevalent?

Well, less oil vapour would appear to be getting to the intake ports.

[Insane_Dawe]

Originally Posted by M Fifty

Well, less oil vapour would appear to be getting to the intake ports.

That is a factor but another huge factor is the valve seals. Depending on the tolerances, some oil will get from the cams onto the valves. BMW may have changed the valve seals to be tighter on a N55.

A thicker a.k.a. fresh oil would help prevent this issue.

[DrivingPassion]

Originally Posted by Insane_Dawe

That is a factor but another huge factor is the valve seals. Depending on the tolerances, some oil will get from the cams onto the valves. BMW may have changed the valve seals to be tighter on a N55.

A thicker a.k.a. fresh oil would help prevent this issue.

I thought the mixtures of oil, vapor and air is channeled through the PCV into the intake valves?