1) Assuming you're taking your distributor out, it's a really good idea to put a mark on the distributor body and the block so that you can put it back in the same position. 2) The distributor is driven by a helical gear on the intermediate shaft. The distributor then drives the oil pump below it. The oil pump drive has a 'peg' sticking up which engages with a slot in the base of the distributor shaft. With the distributor out, align the 'peg' so that it points exactly towards the hole that the distributor clamp bolt screws into. Doing this will allow the distributor shaft to engage correctly when you insert it (but don't put it back yet). 3) You now need no1 piston at TDC (top dead centre). No 1 is the nearest to the offside on a RHD car. There are marks on the camshaft gear to show TDC, but I find removing the covers fiddly. I recommend removing the spark plug on no1 cylinder and putting a long screwdriver in so it's sitting on the top of the piston. Jack up the car so the nearside front wheel is off the ground and put the car in 5th. Now turn the nearside front wheel by hand until the screwdriver is at its highest point. If you remove the plastic plug out of the hole on top of the bellhousing between gearbox and engine, you will see the flywheel. A slight adjustment in position of the nearside wheel should move the flywheel slightly so you can see the marks on the flywheel for TDC. 4) Pick up the distributor (without its cap). Remove the rotor arm and the plastic dust cap beneath it. On the shaft, there is a metal cylinder. Check that this cylinder has only one cutout on its circumference. (If it has four, you have the wrong distributor). 5) With the distributor still in your hand, replace the black dust cover and the rotor arm. With the dust cover correctly seated (two notches for it) you will see that there is a little cutout on the outside of the dust cover. Position the rotor arm so that it points towards the little cutout and with them both at 2 o'clock. 6) No 1 piston is still at TDC, isn't it? 7) Keeping the rotor arm oriented at 2 o'clock, insert the distributor so it engages with the oil pump peg, engages with the helical gear and seats correctly. The rotor arm should still be pointing to 2 o'clock. 8) If you don't get the distributor to engage correctly, check that the oil pump peg is still pointing at the clamp bolt hole before retrying. 9) With the distrubutor correctly seated, refit the clamp and tighten the bolt so it still allows you to rotate the distributor body. 10) The rotor arm is pointing to 2 o'clock. Rotate the distributor so that the cutout in the dust cover is exactly aligned with the centre of the rotor arm contact. (The wiring conector sticking from the side of the distributor should be at about half-past-five.). 11) Replace no1 spark plug - and the inspection cover cap on the bellhousing. Refit the distributor cap and make sure all ht leads are correctly fitted. Connect the wiring connector to the distributor. Lower car to the ground. 12) If you didn't do step #1, do it now, so you have marks you can see - that line up. 13) Start the car - it should run. (You did knock it out of 5th first? ) 14) Stop engine - and connect laptop with vag-com / VCDS. 15) Ignition on, start vag-com / VCDS - go to engine module 1. 16) Open Fault codes - and clear the Fault code '00515 Hall Sender G40 signal outside tolerances' that's almost certainly there. 17) Close Fault codes and go into Measuring Blocks. 18) Select Block 007. The first two items are hall sensor correction. 19) Start the engine and observe the figures in these two items. You need to rotate the distributor body until you get a value of between 57 and 60 - or 1 in the first block and the value in block 2 is between 5 and 8. (I got 1 and 7 by turning the distributor body anti-clockwise so its base rotated about 7.5mm from the tdc postition.) 20) Switch off engine, then ignition back on. Clear the Hall Sensor fault code if it has come back. Ignition off. 21) Tighten the distributor clamp bolt. Assuming everything else is healthy, you car should now rev smoothly to the redline. Notes: If it's limited at about 5,000rpm, the Hall Sensor fault code is there and your distributor is not set correctly. What does the Distributor Hall Sensor do? It's simply a replacement for the contact breakers of a regular distributor, telling the ecu when to charge the coil and when to fire it.It works using a digital on/off mechanisim, using three connections-pos, neg and 0. A slotted wheel spins around and blocks the pickup once per spindle revolution. (The 8v distributor has one slot in the wheel, 16v has four.) Fault code 00515 Hall Sender G40 signal outside tolerances TO Bring the Hall sender unit G40 back inside the tolerance, you must use VAG.com because the timing is controlled by ECU. To do that go to 01 engine, then measuring block go 07 then loosen the mounting bolt of the distributor then turn it anti or clockwise until it gets inside the range. The ECU will trigger the coil even if the distributor hall sender is unplugged, an ADY or AGG will run almost as well as normal up to 5K rpm with the hall sender unplugged, all it does is to tell the ECU where number one piston is so as it may initiate sequential rather than full group injection. Vag Com /VCDS block 007 Blocks 1 and 2 are Hall Sensor correction. Block 3 is Altitude correction. Block 4 is Operating Cond Throttle 00000000 throttle closed, 00000001 Throttle open.