1.9 TDI AFN Engine, does not preheat and over-oils

Hello everyone...

I have here a Seat Alhambra 1.9 TDI AFN, manufactured in 1997.

For about two weeks, the engine has not been starting. Using the long starter cord, the vehicle was able to be started. If the water temperature sensor was disconnected, it would start to glow approximately 30 seconds before it came loose without any problems.
Currently, the problems have expanded, meaning the vehicle is no longer starting. It can only be moved by dragging, extremely sticky.
We have replaced the water temperature sensor up to now. We have also replaced the engine control unit. Motor to control unit wiring checked and control unit wiring, relay, fuse, and ground point wiring checked, everything is OK.
The old engine control unit indicated an error message: "Control unit defective."
The new control unit does not detect any errors; the measured values for water temperature, fuel temperature, and intake air temperature are correct.

Who has any further suggestions for where to look?

Thank you in advance

Ashanti06

Do you have voltage on the light bulbs, i.e., are they actually glowing?
Does the starter spin fast enough? A TDI needs a minimum starting speed, otherwise it won't start. Given the age of the car, I could easily imagine that the starter motor is to blame.

What do you mean by over-oiling?
Does he smoke black tobacco or something?

By "overfueling," I mean that there is so much fuel that even with pre-heating, only white smoke comes out and it doesn't start. My opinion is that the starter doesn't affect the pre-heating process. When I turn the starter, it seems to spin fast enough.

What measurement values are necessary for the control unit to enable preheating?

Hi,

Quote:

What measurement values are necessary for the control unit to enable preheating?

Coolant temperature must be below 5°C, therefore check block 7 in the engine.

If you're already at it, you can also use the TDI timing checker to check the injection start. Not that the timing/injector position is incorrect and the injection timing is not correct.

Hello, Rainer

Quote:

Not that the timing/injector position is incorrect and the injection timing is off.

Yes, and there is also the KW - gear. Is the pulley still running smoothly?