Do these two videos show the intake valves fully closed before direct injection and fuel ignition? If so....that's good news for the M271 CGI, right? If valve is closed, no soot can get into intake to causes carbon deposits. I don't know what the video means exactly, since I don't speak German. Anyone translate? There are two (max 2 mins long) below:

Crickets.....(no one that drives a German car actually speaks German? i'd love to know what the two videos mean.)

Carbon like deposits in the inlet manifold & on the valve tulips is not created from combustion blowback during valve overlap.

It is caused by the by-products of poor fuel collecting in the inlet system from captive crankcase breathers & from burnt on VI improver from oil coming down the valve stems through the guide seals.

Pre DI vehicles allowed the detergeant in the fuel to clean this off but only where it can get. With a DI engine the fuel does not really get into the inlet manifold to clean requiring the use of better fuels. Benz tries to pulse the injector while the inlet valves are open to try & help with this. Other manufacturer like VW & Toyota have now put a LP injector in the inlet system to control deposits.

Here is a M271 pre DI run on Techron. You can see where the fuel could get & keep clean/cleanup.

Thanks Glyn!

Just curious...do you know what the difference is between the two videos? Is one CGI and the other CDI?

Both are spark ignition direct injection. The first shows fuel injected just before the top of the compression stroke whereas the second shows injection during the intake stroke which would give greater cooling & mixing.

I don't speak German. Will try & get us some help from a colleague.

Great! The animations are so cool, I am interested to know what they are saying.

Waking up this old thread to see if any new members speak German

Here goes the translation, i will get around to doing the second video later, sorry!


First Video:


From the sucked-in air mass, the motor electronics calculate the amount of fuel to be injected, and corrects it additionally through oxygen sensor emission control.

Using this operation method, a torque increase of up to 5% can be achieved.

This is attributed to:

1. The thermodynamically favourable cooling effect of the direct vaporization of the fuel inside the burning chamber.
2. higher compression of motors with benzin direct injection in general.

For these various opertaion types, the motorol controller MED7 is faced with two central tasks:

1. The injection time instance has to be adjustable based on operating point between "late" during the compression phase, and "early" during the suction phase.
2. The setting of the sucked-in air mass has to be decoupled from the accelerator pedal position. This is to allow unthrottled motor operation in the lower load area, and throttle control in the upper load area.


By optimal use of the benzin direct injection, an average saving of 15% can be achieved using this technique in relation with the European driving cycle.

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Thanks for the reply!