I got intrested in tuning the engine after reading this very helpfull how to on another forum, vwdiesel.net
http://www.vwdiesel.net/phpBB/viewtopic.php?t=579
Although the basics apply some of the details in that "how to" are a little miss leading as the pump looks diffrent to most UK models. Its also a little over complicated!
Anyway this is what Ive done to my engine.
1/ First of all you need to get a boost gauge. DONT spend a lot of money unless you want to mount it on your dash. Any air pressure gauge will work, youll need something like this http://cgi.ebay.co.uk/40mm-Pressure-Gau ... dZViewItem
You need the gauge to make sure you dont over boost the engine, a AAZ will cope with 15psi with no problems. The std boost should be between 10-12 psi. Connect the gauge.
2/ Adjust the fueling. You cant increase the boost without more fuel! This is the max fuel screw.
Break off the anti tamper collar so you can adjust it. With the car idling and up to temperature, loosen the locking nut and turn the screw in to increase the idle speed to around 1200-1300rpm
Then adjust the the idle stop screw to return the idle to normal
You may need to move the collet further along the cable of the cold start solenoid as well.
3/Adjust the wastegate. This is easy, remove the locking tab, and adjust the wastegate arm towards the end of the threaded rod to increase boost, keep trying it up the road to make sure you dont exceed 15psi. Make sure you properly tighten it back up!
You will then need to test drive the car to fine tune it (revving the engine will not give proper boost levels, you need to put the engine under load). Look for a max boost of 15psi, if the exhaust produces a lot of black soot under boost, then turn the fuel screw back out a little until soot is under control. With these simple mods you WILL feel the extra BHP and torque.
The reason you dont really want to increase boost past 15 psi or have the engine producing lots of soot is to keep the exhaust gas temperatures low and safe, if you want more boost (and therefore fuel) fit an intercooler!
I did try the solenoid mod mentioned in the vwdiesel.net how to, but found that it made no real diffrence and put the EML light on!
Ive also blanked off the EGR valve on mine which I found make a supprising diffrence to the drivability of the car.
Last week I also fitted a 1.6TD boost pin (read the vwdiesel post for an explaination on this one) with has allowed me to get better on boost performance. This pin fitted to all golf/ passat 1.6tds and also some peugeots and volvos with a bosch VE pump.
AAZ boost pin on left, 1.6 pin on right
Easy and worth doing if you can find the correct pin!
Anyway hope this is of use to you AAZ drivers, if you spot any mistakes or something Ive missed, feel free to put me right!!