Thread: 1997 300tdi Auto Massive Fuel Guzzler

This is a cry for help. I need to go away in just over a month and the projected fuel costs could be a major issue. I have a 1997 300 TDI Auto with multiple accessories. Let it be known that the problems started well after these were fitted! And my fuel economy has gone through the roof. Literally between tanks. One week I was getting 750-800kms a tank then the next went down to 650, the week after 550. I now average 550-450 depending how I drive. THe change was completely random, i.e. I hadn't done any work on it for a few weeks. I have done the following diagnostics/repairs on it but am leaning towards the g-box slipping or even a timing belt slip.

Brand new water pump, rad, thermostat, silicon intercooler hoses, and penrite coolant.
New injector return lines.
New viscous coupling.
Lift pump spurts nicely.
Injectors have been tested and all break cleanly between 190-200 bar. Spray patterns are what you would expect of used injectors.
Intercooler has been flushed.
IP doesn't seem to be leaking anywhere, neither do the fuel lines or tank. It only drops oil on clean concrete! I have inspected the motor when both cold and hot for leaking fuel evaporating but no luck.
I have removed the pressure hose between the turbo and IP diaphragm and inspected/cleaned. No holes.
Turbo has a good kick, vanes are clean for the age.
My cheap EGT gauge reads about 200 to max 650 on the hwy with foot to the floor.
TM2 reads 88-89 (never lower, as my last disco did) in normal city driving, spiking to 91 when I come to a stop in the traffic. (As you would expect.)
Aftermarket water temp gauge fluctuates around the same, i.e. rising and falling faster.
Factory gauge reads whatever it feels like on the day!
I have only used one fuel supplier in the last 2 years. Only switching recently when clutching at straws I thought it might be the issue.
There is no excessive pressure in the coolant exp. tank.
Seems to change gears at the appropriate RPM.

Points of concern are:
Unknown exact date of the last timing belt change. All data points to around 60 kms ago. (It was a insurance short motor with 40k on it.)
Auto stall test gave me 2250 rpm. Anyone know the exact speed it should be? My Rave Cd is corrupt.
I have not done a compression test.
It does not have a heater core. Hoses are looped, not blocked.
I can feel the g-box temp through the gear shift. Not too hot but def not warm, warmer than you would probably drink tea anyway.
Wouldn't change out of first when cold. Mostly fixed since last oil and filter change.
My last auto, also kitted out, once gave me nearly 1000kms with a tailwind up north so I know it is possible!

When I remember what else I have done I will post it up! Any input would be much appreciated. Thanks for the help!

Regards,
Lane

Valves and rockers all checked, twice! Does anyone have a stall speed in their RAVE manual so I can rule out the auto and torque converter?



Regards,
Lane