What you are experiencing now is too early to be the result of any build-up. It does sound like the octane rating for the fuel is too low.

Keropur is a good approved fuel additive to increase cleaning action:

mbworld.org MB-approved keropur-basf

To clarify your engine, for further advice:

gasoline or diesel?
if gasoline, RON Octane number for gas used.
turbo?
displacement?
direct fuel injection?

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I fully concur with Kevin here. Way too early for the carbon issue to show its ugly face, if ever! Fuel additives are not very effective on DI engines since the compounds hardly ever come into contact with the valves. You may have anything from a dirty/clogged fuel filter (if you filled up at a poorly maintained station) to a poorly blended batch of gasoline, to a malfunctioning flow sensor, or coil pack. Since you didn't mention any thrown codes, I'd place my bet on bad gas!

 

Most likely a low MON gasoline being used. I'm sure that Benz will be able to provide a suitable ECU tune for your market. They are well aware of fuel quality.

 

Thanks Guys, you are very helpful.

The engine is the petrol M271EVO 1.8 turbo mated to a 5 speed box，I used RON98 gas (but in China the fuel quality is really unsteady). is there any driving habit change to better cope with the issue. The car is used mostly in short distance stop-start traffic?

Just curious, can an ECU tune solve or just minimize the knocking and carbon build up issues in an area with low fuel quality for a DI engine? And I read elsewhere that fuel additive may not help in DI engine as the additive will not be able to reach the top of the valve, is that true?

 

China is an extremely important market for Benz. I'm sure that they will release a revised ECU tune capable of retarding timing futher at the onset of knock.

In the mean time do not lug the engine. Rev it and it will be less inclined to knock. Don't accelerate hard at low RPM.

98 RON gas should be fine but as you know sometimes the gas does not meet spec.

I have spent a lot of time in China - Love Shanghai!

 

Thanks Glyn, it is really helpful ;-)

 

Our N54-equipped 135i has been diagnosed with excessive carbon buildup on the intake valves @ 45,500 miles. BMW says it is not a warranty issue and if you wanted to be technical they would be correct. It is not a defect, it is a design characteristic of the DI engine.. $893 to clean the mess up then it will be traded before the year's up.

 

After I started this thread, we eventually found that fuel cleaning additives ARE effective in cleaning the intake valve of some DI engines, like MB, that were designed for DI. The injectors are angled so they partially hit the back of the intake valve when they are open.

RON98 is about like USA 93-94 AKI pump rating, which should have sufficient octane, but not if the fuel is not really at that RON level.

Like Glyn said, use a soft pedal at low rpm starts. Is it 5 speed automatic? Either way, use manual shifting in city traffic to be sure you keep it in higher rpm range, and don't make the engine downshift automatically.

A tune could change the boost and timing curves to minimize knock, but will do little to stop any carbon build-up.

-> Just curious, how do they control the quality of the gasoline, and are the gas stations national or private?

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+1^ ~ Was at my dealer last Friday to pick up a printout of the history of my car from the Benz system. The dealership is owned by MBSA. Fortunately no gremlins other than arriving from Germany with a flat battery which was replaced - not charged. My service manager is a great guy.

I asked him if they had seen any deposits in inlet systems of DI cars as yet. He says none thusfar. He said I was welcome to pop through at any time and we could take the highest miler customer car in for service & have a look with a boroscope. I might just take him up on the offer out of interest.

 

This is starting to sound like a replay of the poor gas issues from the mid-80s. At least at that time some manufacturers covered the problem under warranty. We had an '84 5000 that they walnut shell blasted the valves for free.

I certainly hope that MB doesn't fall victim to the same fouling issues. The wife wants a new car and it's hard to find one without DI.

 

The gas stations are mainly national oil companies like PetroChina & Sinopec. The International guys like us have a few in partnership with Stanley Ho, Langton Investments & the likes. Opportunities are opening up.

 

BMW told us it was our fault because we either don't drive it hard enough (are you kidding? no one special orders a 135i 6MT to drive like a granny) or because we use low quality gasoline.. needless to say, he assumed I knew nothing about direct injection. He is not too fond of me at the moment.

I hope Mercedes doesn't have this issue. Also have a Lexus IS350 in the stable and at 75,000 miles no issues. Then again, with Toyota's port and direct injection it should never have the issue. The 250s on the other hand..

 

Sorry Kevin, I concluded this in an earlier post. It's a theory of mine, not proven, at least not yet.

 

I believe Glyn has more insight to the Chinese oil industry. There are 3 types of gas stations, those directly operated by oil companies, franchised station of oil companies and private station. In major cities like Shanghai, i would say most are the first 2 types. As this industry is very protected (by government) and the operations I believe is very corrupted. You will expect there will be a lot in problem in the production and distribution process. It is said that petrol supply to Shanghai follow a standard very close to Euro4. But the real quality is difficult to say because of the corruption and the most recent news is thousand of cars were damaged after filling up in a PetroChina franchised station in a second tier city. PetroChina insisted there is no problem with the petrol but a compensation of RMB 3500 (around Euro400) is given to each damaged car owner. I would say the further away from major cities (e.g. shanghai or Beijing), the issue become worse. So I expect the quality variation across China is really big.

I don't know how well the Mercedes engineer understood China when they tested the V212 in China. I am a bit worry as least MB is now suffering from a poorly set up distribution and my e260L has an Euro12000 discount (i.e. around 20%, can be more if pushed), and it is a typical sign of distribution design failure based on my experience in Pharmaceutical distribution. Chinese will buy less when the price is dropping, they just speculate for a further drop. I guess most E class owners in China are using their cars for business and it is not uncommon to reach more than 50000km in 1 year, and these ultra high mileage cars may concentrate in poor fuel quality areas as they tend to drive from second / third tier city to major city for business.

So it would be interesting if we can see more example of how the carbon build up will be in long term.

 

But I recall searching on some sites, posted any not, where you could see animation of the fuel spray on some engines hitting the back of the valves ... might have been yours ! I guess there's still a question as to whether it's "effective" or "not very effective" ... I tend toward the former for the MB.

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At our Shanghai Gaoqiao JV with Sinopec labs we have seen numerous petrol samples that don't meet specification.

 

don't meet specification

Octane Rating?


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To be exact, that is a design defect of the earlier DI engines that VW and Mazda also experienced, as well as others.

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Yes if it's available. Until then, your brain will have to act as the ecu tune. As Glyn said, avoid loading the engine at low rpm, esp at starts. And anticipate when a down shift is needed, and don't wait until you lug the engine. Not a bad time to learn double clutching ( with pause in neutral & clutch released) when down shifting ... it's fun when mastered.

 

Octane, Distillation curve etc.

 

Sorry Kevin, auto box......

 

Inside the Direct Injected 350 after 10,000 miles...

 

I admit that I'm a bit scared about the DI design of the new 3.5. I've heard many horror stories from Mini owners with their DI engines... I'm hoping to find that there's some brand of gas that's better for minimizing this risk. Either that or I guess I should start seeing how much effort it will be to take off the top half of the engine in 4 years.... I'm hoping I don't regret not buying Ford...

 

Notwithstanding known DI issues, why did you have the head(s) off?

 

That is a combustion chamber deposit ~ not a result of DI but poor fuel/combustion. BASF material or Techron will help.

My dealer service manager took a look at a fleet car M276 engine a few weeks back with 45,000 Km's on it and the inlet valves were clean. Unfortunately his boroscope had no imaging capability. We will get some pics sooner or later & continue to watch this out of shear interest. Fortunately the thick deposit seems quiet fuffy & likely to blow off.

SA's fuel is not great. We will only be Euro4 in about 12 months from now so we are lagging.

I'm interested in the reply to splinter's question.