what are the causes of heavy black smok in ml430

Black smoke is a sign of too much unburned gas. Some things to check for include fuel pressure too high, a fuel injector stuck open, defective mass air flow sensor, and coolant temperature sensor. Most mechanics will start by connecting a scanner that displays live data to see what the Engine Computer is seeing from the sensors. It's from those readings that it calculates how much fuel is needed.

when i unplugge the mass air sensor nothing change
but i dont know what it main?

Unplugging a sensor isn't going to fix anything. The Engine Computer will substitute a signal from memory to replace the missing signal from the unplugged sensor. It's anyone's guess how it will run that way.

thank you for your usefull answers

my mass air sensor number is0280218083 but i cant find the same number with the parts supplyer.
i want to know if there is substitute number i can use.
thank you

what is maint by the code number 40400

I found four on rockauto.com. Normally we don't worry too much about the original part number. We just go by application. The part numbers from the dealer will change sometimes too when a change is made to improve something.

i have another mercedes benz 560 sel model 1991
but the problem is the speed fixer is not working at all time.
would you please tell me what are the posible resons of such trouble
thanks

Not sure what you mean by "fixer". Do you mean the speedometer stays on "0" sometimes? Two things come to mind for that. There will be a speed sensor on the transmission. Those can be intermittent. The electrical terminals in the connector can spread too and make poor contact. If your transmission is computer-controlled, it will usually not shift properly when there's a problem with the speed sensor or its wiring.

Sometimes connector pins on the back of the instrument cluster work loose. There are different problems that can occur depending on which pins are affected. Usually those can be fixed by carefully soldering the pins to the copper circuits.

no i dont main speedometer
i main when i need to fix the speed regularly at any
number for examble if i need to keep the speed
on 100/km/hr so that one fixing the speed at that number
is not working

Do you mean the cruise control, or speed control, that lets you drive with your foot off the gas pedal? That usually requires a scanner to access the Engine Computer to see what's working and what isn't. If you have any type of light that turns on when the cruise control is turned on, and that's not working, you might suspect the "clock spring". That is a wound-up ribbon cable in a plastic housing under the steering wheel. Two of the circuits in that cable are for the cruise control switches. It's common for those cables to break. Very often the horn doesn't work either.

The scanner will display the switches and whether they're on of off, and it will show if the computer is trying to activate the servo under the hood. If it is not, it will show why. If it is, but it's still not working, either the servo is bad or its throttle cable is broken.