[Vwdiesel] Brakes --- engine brakes -- ( The physics of it ).

[LBaird119 at aol.com]

that engine doesn't seem to settle down very fast

  Reminds me of my 914 before I "fixed" it.  Pre 73 914's had D-Jetronic 
injection, which is MPC (Manifold Pressure Controlled).  The EPA 
apparantely required some sort of lean burn deceleration device.  In 
effect what it ammounts to is a 7/16 hose bypassing the throttle body 
whenever vacuum is over about 24 inches (adjustable).  Let off the 
throttle, such as going down a long hill, and it lets "extra" air in to 
lean out the burn and reduce unburned HC, CO and so forth.  Problem 
is with MPC, the sensor reads the bypass as "more throttle" so it 
injects more fuel.  You get the same burn but it takes about 10 seconds 
for the engine to return to normal idle whenever you rev it or let off! 
Disconnect the whole thing and it's a normal up and down on the tach.  
  I wonder if some stupid thing, similar to that is at work on the TDI?
     Loren