Ibiza TDI Problems: Common Issues & Solutions

I have a Seat Ibiza TDI, manufactured in late 1999 (latest model), with a conventional distributor injection system. The problem is that the idle speed is sometimes increased by about 300 RPM. Also, the glow plugs often activate even when the engine is warm. When I start it, it briefly revs on its own, and a cloud of black smoke comes out the back. I also suspect that it's using slightly more fuel. I reported these issues to my authorized service center during the inspection, but nothing was done; it seems the error codes weren't read. Despite that, the inspection cost over 500 euros. I'm fed up with this workshop. What could be broken (temperature sensor?) If so, where is it located? Does anyone have a VW part number so I don't have to go to a Seat dealer?

Hi.

The coolant reservoir is typically located in the upper, wider part of the coolant outlet, facing towards the radiator.
If it's the 4-pole dual encoder version, things get a bit complicated.
Disconnect the plug, turn on the ignition, and measure the voltage of the two terminals.

Then, connect each of these two sensors, one after the other, along with the corresponding mass connection, by bridging them with a 270 or 330 Ohm resistor.
Here's how you can find out (by turning on the ignition) which two connectors are responsible for the EDC - namely, the ones where the temperature gauge does not move.

Next, insert the 270 / 330 Ohm resistor (0.1 Watt is sufficient) between the EDC connector pins and start the process. This simulates a hot engine (approximately 85°C), so a cold start behavior should not occur.
If so --> Check the wiring harness and connector at the engine control unit.
If not: Replace the donor part. Unfortunately, I don't have the part number, but it should be the same as the one used in the VW with the corresponding engine, in my opinion.