Golf IV TDI starts poorly when the engine is warm - DKE is okay

Hello diesel mechanics.

I've been having a major problem with my G4 again for the past two weeks.
As soon as the engine reaches its operating temperature, and I turn off the car (whether it's for 2 minutes or 20 minutes), and then try to start it again (even after pre-glowing), it takes almost 10 seconds for it to start.
The throttle body unit is in good condition and has been cleaned.
Do you have any idea what the problem might be?
Nothing was stored in the error memory.
When the engine is cold (below 70°C), it starts immediately (after preheating).

Hi,

Interjection: How are you supposed to get hot at these temperatures? It's practically impossible... it only really starts happening below 5...9 degrees Celsius. If it still overheats, the temperature sensor is likely faulty.

The brief flash of light after turning it on is *not* a warm-up period (if that's what you meant); it's just the self-test. Before the main light turns on, it glows for a longer period, and you can also hear the pre-glow relay clicking (at least when the display turns off).

Best regards,

Jan.

P.S.: I've moved your post to the correct forum.

Oh, okay.
I always turn on the ignition until all the lights are off, and then I start the engine.
Is that not necessary?
Can I start it in warm temperatures like a gasoline engine?
I've only had the diesel car for 2 weeks.

Hi,

You can start the engine when the preheating indicator is off. However, at the current temperatures, it usually turns off after a maximum of one second (because that's when the self-test is complete). The ABS and airbag lights may remain on for a longer period, but this also happens in gasoline-powered vehicles. So, you don't have to wait.

Below around 5 degrees Celsius, the preheating process starts, which you can observe. Then, it stays on for a noticeably longer time, and this duration increases as the temperature drops.

Last winter, I also accidentally (because I was in a hurry) started the car at -8 degrees Celsius without pre-heating. It rattled and shook quite a bit, but it started right away. It's not a good idea, so it's best not to copy it.

To help me understand your problem better, please provide more information.

Which engine? (Horsepower, and ideally the engine code letter, which is usually found on the service sticker).
What do you mean by "throttle body assembly"? This is a diesel engine, which (in most cases) doesn't have a throttle valve, but only a shut-off valve (and not even that is always present).
Mileage?

Best regards,

Jan.

Hi,

/viewtopic.php?t=3094&highlight=starting+problems+when+warm

Quote:

Low starter motor speed despite a fully charged battery: -> If the engine starts immediately when jump-starting or rolling, first verschandeln all the corroded contacts between the battery and the starter. -> If crimp connections, cable kinks, etc., become hot quickly while playing the organ, replace these cables. -> If all the cables are okay, then replacing the starter motor

might improve the situation.


The starter motors often fail in the G4 model. In a flooded state, it is no longer possible to reach the required engine speed, and the engine starts very poorly.
Here's a possible translation:

"A possible test: Disconnect the coolant temperature sensor (this simulates a cold start for a warm engine)." If the engine starts immediately and without any preheating, the problem is likely related to a low starter motor speed (due to corrosion of the contacts, a faulty starter motor, etc.).

H
Often, the starters fail in the G4 model.

Often, it's simply a battery that has lost its capacity.

btw Sven... the search function is your friend!