View Single Post
  #7  
Old 11-10-2009, 12:36 PM
mcreynol mcreynol is offline
Registered User
 
Join Date: May 2001
Posts: 44
Turbo control

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.
It appears that the ECU firmware was designed to do far more than simply protect from overboost/overspeed. This bodes well for using the ECU to directly control a VNT turbo.

Some of the wastegate movement may be designed to develop backpressure to enhance EGR flow.

Last edited by mcreynol; 11-11-2009 at 07:27 PM.
Reply With Quote