Volkswagen Golf III - Bosch pump timing, how does it work?

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Sun 5 Dec 2010 14:32
Volkswagen Golf III - Bosch pump timing, how does it work? - hrvoje dagelic

Hello,

I want to mess around the timing on my 1.9 TD, AAZ (advance it a bit), but I can't figure out how the timing solenoid (if it is a solenoid) on the bosch pump works. I've been searching on google, but there is very little info about it.

The timing advance/retard is electronicaly controlled and the piece in the engine has two wires going to it, both live, showing around 5 volts to ground. I've read that you can advance the timing by putting 12 volts to that piece, but where if there are 2 live wires? Do I ground one of them, or you can regulate the timing by varying voltage between them or on only one of them?

Can somebody please explain me what that thing is and how it works, or post me some link about it...

Thanks.

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Sun 5 Dec 2010 15:39
Volkswagen Golf III - Bosch pump timing, how does it work? - Peter D

The injection tim on this vehicle is not electronically controlled. From memory the toothed drive sprocket is adjustable. The solenoid is the fuel cut off valve. Regards Peter

Edited by Peter D on 05/12/2010 at 15:50

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Sun 5 Dec 2010 16:15
Volkswagen Golf III - Bosch pump timing, how does it work? - injection doc
if you advance it , it will make it very nosiy, smokey ( black) and run the risk of burning a piston!
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Sun 5 Dec 2010 20:23
Volkswagen Golf III - Bosch pump timing, how does it work? - Railroad.

Check visually the system components. Do you have a Mass Air Flow Sensor? Do you have a Needle Lift Sensor on one injector? And does the engine have a Coolant Temperature Sensor? If the answers are all yes then you have an EDC (Electronic Diesel Control) system and in this case the precise injection timing is controlled by the ECU.

However, the pump needs to have a base setting which is altered by adjusting the relationship between the pump shaft and the pulley. The engine can be difficult to start if it's wrong, or other problems such as excessive diesel knock may occur. There are no marks to set this up, and so it can only be done with the appropriate diagnostic equipment. Any adjustments made without will only ever be a best guess. The base timing should be checked every so often, and especially after a cambelt change.

VCDS available from Ross-Tech will enable you to see the base pump timing in graph form and in real time. You then make adjustments until the graph shows the timing to be correct. I do have VCDS and I'm in Hampshire if that's of any use to you.

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