What is the MAF doing to cut off the boost? - PeachParts Mercedes-Benz Forum

Olivier · #1 12-31-2009, 11:19 AM

Just wondering as I checked the wastegate manually while reving the car but nothing is moving, but there is still no boost without the MAF?
Is the MAF directly affect the fuel or is the wastegate open all the time untill the MAF close it for some boost?
Thank you.
Olivier

Olivier · #2 01-01-2010, 05:28 AM

After some search I got this:

Quote:

Originally Posted by mcreynol

I spent some time and instrumented the boost control signal on my OM606 G. This is a 10V PWM signal produced by the ECU. It controls a vacuum modulator that then pulls the wastegate closed. The results are interesting. The ECU is constantly playing with the wastegate.

Acceleration: the wastegate is held closed until the max boost is reached
Pedal lift: immediately opens wastegate
Idle: back on full boost (not that any boost will be produced)
Steady & flat @45mph: wastegate partially applied
Steady & flat @65mph: wastegate partially applied
Shift points under hard acceleration: wastegate momentarily opened between shifts
Driving on rolling hills moves the wastegate back and forth constantly.
.

My MAF is out and as I said earlier nothing is moving on the wastegate area when I am on park and manually accelerate, would the MAF out open the wastegate right away? As above stated on idle it should be close?
Cheers.
Olivier

muleears · #3 01-01-2010, 05:37 PM

I'm way out of my area of expertise but I don't think you can test the turbo boost with the car in the driveway. I don't think they develop much, if any boost without a load. I'm sure someone will correct me on this!

Olivier · #4 01-01-2010, 05:59 PM

Oh... Thanks. The bother is that its a wee hard to manually test or look at the wastegate a hand under it and a hand on the steeringwheel.

I need a MAF or the Mdisav MOD...
Still wonder how the MAF cut it tho.
Cheers.