ECU Adjustments
There are two ECU adjustments relating
to fuel and air delivery that are
relevant when changing to larger
injectors:
idle injection quantity and EGR adjustment.
Both of these adjustments require a VagCom (
Ross-Tech: Home) or VAG scan-tool.
You might also want
to check injection timing while youíre at it.
Idle Injection Quantity:
Larger nozzles will deliver more fuel than the ECU thinks that itís delivering.
By changing the idle injection quantity (which is sort of a misnomer),
your recalibrating some constants in the ECU relating to fuel delivery which results in better idle speed control and, depending on the state of
your particular engine, less smoke
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EGR Adjustment:
At idle and part-load situations, the EGR system recycles some of the exhaust gas into
the intake. This reduces NOx emissions. Itís possible to reduce the amount of EGR so that there is less
exhaust recirculated and more fresh
air. More air is good, because your
larger nozzles mean more fuel!
(Note: this is a good idea even for stock engines, since less EGR means less soot to gunk up the intake.
The procedures are in this tdiclub faq. pdf.
http://pics2.tdiclub.com/pdf/injector_install_howto.pdf
You will need to find someone with VagCom in your area or pay to have it done.