basic TDI technology question

gern_blanston

Veteran Member
Joined
Dec 3, 2002
Location
PNW
TDI
Golf, '03, Silver
OK, I understand how the 2-stage injectors make every combustion event a smooth one-two punch, and I looked at the pump pics that DBW posted. Can someone explain in very basic terms, how the ECU varies fuel timing and quantity? Thanks.
 

gdr703

Veteran Member
Joined
Jun 13, 2002
Location
Vancouver, Canada
TDI
Golf 2 door 2002 Indigo
I read on this forum a post some time ago I think by DrivebiWire that expalined that the cam plate that provides the one two injections can be rotated to advance retard the timing. Also there is a control collar that is positioned to relieve the pressure as the oscillating plunger slides.
Do a search on Injector Pump maybe sometimes in 2003, in the 101 section, authored by DrivebiWire.
 

Raxum

Veteran Member
Joined
Jun 11, 2004
Location
San Diego CA
TDI
98 Beetle
This is how I understand it.
A cam moves the plunger for start of injection.
The Quantity adjuster turns a collar to dump presure to end injection.
The cold start injector (not a injector at all) is a electro-mechanical device that actuates a pintle. This pintle, when open allows hydraulic pressure to influence the injection timing piston.

Source: TDI Diesel Design and function ssp841103
 

Cincy_Mike

Veteran Member
Joined
Jul 25, 2003
Location
Cincinnati, Ohio
TDI
Auto 2003 Jetta GLS TDI - Galactic Blue
Dunno if it's too basic to be of use, but VW.com has animations explaining their different engines-- including the TDI.
 

tadc

Top Post Dawg
Joined
Apr 13, 2001
Location
Stumptown
TDI
Golf GLS TDI, '01, Black
The fuel timing is sensed using the #3 injector's Needle-lift-sensor to determine the exact start of the injection event, and the crank position sensor to determine the engine position. Quantity is sensed indirectly, by the rate of change at the crank position sensor.

What goes on inside the pump, however, I'm also a little foggy on.
 

gern_blanston

Veteran Member
Joined
Dec 3, 2002
Location
PNW
TDI
Golf, '03, Silver
Bingo. Thanks, DB. I hadn't remembered the moveable collar. I think I must owe you a root beer or Latte' or something (since we're both Oregon pilot types.) If you're ever headed to SLE, drop me a line, and I'll make sure there's some Henry Weinhard's in the hangar fridge, and crank up the espresso machine.
 

Davin

Top Post Dawg
Joined
Jan 4, 2001
Location
L.A.
TDI
2001 Golf GLS 5spd blk/blk
Quantity is sensed indirectly, by the rate of change at the crank position sensor.
Actually, quantity is sensed by reading the position of the control collar (the "modulating piston sensor" in VW-speak).
 

Drivbiwire

Zehntes Jahr der Veteran
Joined
Oct 13, 1998
Location
Boise, Idaho
TDI
2013 Passat TDI, Newmar Ventana 8.3L ISC 3945, 2016 E250 BT, 2000 Jetta TDI
Correct, Using a the shift in the magnetic field of the quantity adjuster controller Bosch is able to control fueling without any wearable parts or direct contact with the controller sumberged in fuel.

DB
 
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