Features

How to give your Tdi's a performance boost - pictures

by: Auto Express team

27 Sep 2017

The boost pin is inside this housing on top of the fuel pump. There are just four screws to be removed before carefully lifting the cover off.
Take care not to damage the rubber diaphragm, which is against the underside of the cover plate. More haste, less speed.
Remove the rubber diaphragm, but leave the spring in position for now. Lift the white plastic washer out and keep it safe for later.
The sliding pin and diaphragm come out as one unit. Swap the pin for the new boost pin (bottom of picture, with it’s modified profile).
As the new pin is fitted, use a marker to highlight this dot in the plate washer, and align it with the pin’s machined profile.
A mark is also made on the top of the plate washer so we know which way it faces when refitted back into the injection pump.
Grease is smeared on the working surface of the boost pin. The guide pin works against this surface (see mark on original pin in picture 4).
With the spring lifted out, the star wheel adjuster ring (which sets the spring’s pre-load) is reference marked in case it needs adjustment later.
The spring and diaphragm/pin assembly are refitted (note orientation), and the cap is screwed down ensuring the diaphragm is seated in the body recess without any nipping.
Initial smoking was sorted by making careful adjustments and re-tests
After adjustments and five re-checks on the road, the smoke was reduced to a minimal puff at the start of acceleration.