TDI 97 doesn't start properly when warm.

hello,
My TDI (97, with almost 220,000 km) has been having trouble starting, especially after it has been running for a while. This means the indicator/electronic lamp in the dashboard is NOT illuminating.
In normaler Ausführung hört man an der Einspritzpumpe ein leises Klicken (Ich gehe davon aus, dass dies das Kraftstoffventil ist). Dies ist jedoch nicht der Fall.

I also turned off the temperature sensor to simulate COLD, but it doesn't work.

I don't have a diagnostic tool (but I have ordered one), maybe someone has an idea.
Another quirk is that he (even when it's warm outside) seems to lose his charging pressure.
If I then turn the ignition off and on while driving, it's okay again.
It seems like the control unit is having problems.

Hello,

if everything is back to normal after a restart, this strongly suggests that the
Emergency mode.
The best approach is to wait until the diagnostic tool arrives and then read the error codes.

stefan krissel wrote:

hello, My TDI (97, with almost 220,000 km) has been having trouble starting, especially after it has been running for a while. This means the indicator/electronic lamp in the dashboard is NOT illuminating. In a normal situation, you should hear a quiet clicking sound coming from the fuel pump (I assume this is the fuel valve). However, this is not the case.

Hi

Subject to the check for error codes, it seems that the EDC is not receiving power.
No flashing and no clicking sound from the pump (actually, this is due to a check of the control panel) are, in my opinion, quite clear symptoms.

You can measure the voltage at the starter while it's being engaged, with a helper turning on the ignition --> it should at least be 12 volts for a few seconds.
If there's no warmth coming out, --> first check the stupid relay 109.

Hi,

I've also thought about the relay, but why only when the engine is warm.
What I forgot is that it also happened a couple of times during the drive.
In the repair manual, there is mention of the pre-heating system, which is divided into 'low power' and 'high power' modes, according to the schematic, there are two relays. This could be a problem.

Stefan

stefan krissel wrote:

I've also thought about using a relay, but why only when the engine is warm?

Hi

There are indeed intermittent contacts that are temperature-dependent. When the engine is running, not only the machine, but also the relay, slowly heats up due to its power consumption (approximately 0.5 watts)

Quote:

What I forgot is that it also happened to me a couple of times while driving.

Could also be from the relay.

Quote:

According to the repair manual, there is a pre-heating system that is divided into "low power" and "high power" modes, according to the schematic, there are two relays. Could there be a problem there?

HÄH??
This clearly refers to the glow plug heater, which is only active in winter and cannot shut down the engine or prevent starting, even in the event of malfunctions, as long as there are no serious = smoldering short circuits . . .

Stefan

Hi Ulf,

The 109 relay, according to your descriptions, didn't seem to be the problem.
I have checked it, and I always noticed that it switches on and off properly, regardless of how and when (I have been driving without the fuse cover for the whole time anyway).
So, it always switched, but the electronics wouldn't turn on.
Now I've tried it with cheap hard-board PCBs, it's unbelievable! Are Expoxyd PCBs so much more expensive? And a COLD DESOLDERING station at the connection output. I've already reflowed (and enlarged the soldering iron tip).
Now I'll put the box back together tomorrow and take it for a test drive.
I will report on the test drive!!

Best regards
Stefan

Now I've tried it, cheap hardboard PCBs, you can hardly believe it, are Expoxyd PCBs so much more expensive?

Not very much per relay, but per 10,000,000 relays

'I, too, am caught up in the obsession with saving, and it often ends up costing more than I should be saving...'



and a COLD SOLDER IRON at the switch output. I have already reflowed it (and enlarged the soldering iron tip).




A colleague has a 2-series Golf; it seems the relays were also weak at some point. However, this car appears to have a faulty winding, while the rest of the hardware is in good condition.

See you, Gremlin