My 98 TDI AFN has been suffering a warm start problem for about 18 months and although looking at various web forums and remedies I am no further forward!. I was going to replace the car earlier this year but a new car for my wife means I need to keep this running for a few years.

The car starts fine when cold but when the engine temp is more than about 54 it takes about 5 seconds of cranking to start.

So far I have:
  1. Replaced the battery due to failure of the original supplied battery
  2. Replaced the ECT sensor twice although all sensors show they work OK on testing.
  3. Removed and sent the ECU for testing - no fault found
  4. Checked the ECT to ECU wiring - no short or open circuit found
  5. Replaced the MAF due to failure although this made no difference to the starting problem
  6. Checked and replaced various vacuum hoses
  7. Removed and cleaned the started motor
  8. Found no faults with VAG software
However, when I disconnect the ECT sensor by pulling the plug at the sensor starting is fine either hot or cold!

Any ideas on this welcomed.