Power supply for the EDC

Hello @ll.

My 1Z TDi is having trouble starting. I need to run the starter for a relatively long time at a certain speed so that it 'runs continuously'.

Hypothesis: Faulty power supply to the control unit.

I have now replaced the 109 and then started measuring.

Supply voltage according to VAG-COM with engine idling: always around 10.5 volts. Running Motor 12.3 - 12.5.

I have then measured everything imaginable using a circuit diagram. Voltage on the 109 = Battery voltage (12V at idle and 14.4V with running engine)
With a pin, the pin was poked into the connector on the control unit, and also the battery voltage. Then the car was turned off and the cable was disconnected. Everything was measured against the ground of the control unit. Always full battery voltage.

Is my power supply a bit 'broken'? Does it have a constant voltage regulator or something like that? Does anyone know the error?
There are more than just rare days, he jumps around like a TDI. Look at the keys crookedly and suddenly, he's running.

The driving experience is fine. Fuel consumption / Amount of soot is all excellent.

Who can give me a tip???

Thank you.

Hello,

Your measurements for the power supply seem quite good.

Have you also checked the following:
- High voltage at the starter when starting
- Mechanical clearance of the parking aid
- Determining the position of the power supply during assembly? (Measure between pins 2 and 3 with a digital voltmeter, AC). Digital (due to the lower impact on the measuring device)
- Can you rule out air in the fuel pump or fuel lines?

Does your engine only exhibit this effect when the engine is first started or every time it's started?

Hello, Rainer

Thank you for your quick response.

Collector? Are you referring to the fuel pump?

Air can be ruled out. Also, there's also a space heater attached, and it seems to be working.

To make this even clearer: It seems to me that the control unit momentarily loses power when starting. Just measured again when starting, before it got completely dark outside.

VAG_COM indicates that the supply voltage drops to approximately 7.5 volts during startup, and then the connection is interrupted during startup!

I will measure the volume of the material tomorrow!

Thanks, first of all.

DeathAngel69 wrote:

VAG_COM indicates that the supply voltage drops to around 7.5 volts during startup, and then it disconnects the connection during startup!

Hi

Depending on the battery condition and engine start temperature, this may currently be accurate - i.e., I believe it is too risky to conclude from this observation that there is a definite defect in the EDC or its power supply.

Hello,

DeathAngel69 wrote:

Stopp? Are you referring to the fuel pump?

yes,

Quote:

VAG_COM

reports that the supply voltage drops to around 7.5 volts during startup, and then it disconnects the connection during startup!
normal. So, you also experience starting problems with a warm engine?

Hello, Rainer

Yes, even with a warm engine!

Measure the voltage tomorrow!

Thank you for these suggestions and insights. I'll be posting more tomorrow!

Voltage is equal to the voltage of the battery/car battery.
What next?

Hi

Check out haehnleins's cold start thread, there's a discussion about potential issues with the fuel pump there.

So habe ich mich mal eben da durchgewälzt.

One of the problems is preheating. --> This is not relevant, as warm start is also the same, and the car is almost never started cold (Eberspächer)

And the engine was completely overhauled by me approximately 10,000 km ago. (New seals/ O-rings/ PISTON RINGS, etc.)

2. Control unit borrowed --> also no success

Voltage at the battery terminals = Battery voltage.

I also tried using a jumper cable (suspecting a dead battery). Dad's car (300 TurboDiesel) clamped (with engine running) --> no improvement.

Run-time control in VAG-COM --> Where are the 'thresholds'??

What else could it be?

DeathAngel69 wrote:

What else could it be?

Hi

spontaneously, three more things come to mind:

1. Internal locking mechanism --> remains locked even under tension and only opens due to the triggering vibrations.

2. Starter spins too slowly. Test: Roll at 25 - 30 km/h in 5th gear. If he starts well, it could be due to that.

3. The quantity adjuster is set to a low setting.
Hang the VAGCOM and check the idle injection amount: it should be around 4 - 6 mg when warm, without major electrical loads or the air conditioning system.
If significantly more is displayed, it is likely that the starting amount is too small (just believe me in the apparent contradiction), and the car barely responds to the accelerator in the lower load range. This, however, can only be assessed relatively reliably if one has the opportunity to drive a comparison vehicle with a properly adjusted control system.

The differences in the idle run regulation between the cylinders should not exceed 2 mg.

Okay, I've done a bit, the rest will come too

VAG-COM says:

Empty volume 3.8mg/R
And regarding the running smoothness, the 3 fields.
0.7 0.7 1.6
also also mg/R.

Can you/are you understand this?

DeathAngel69 wrote:

Amount of free substance 3.8mg/R And regarding the running smoothness, the 3 fields. 0.7 0.7 1.6 also also mg/R. Can you

understand this?

Hi

yes... it still looks pretty normal, I can't see any direct clues about your problems

Finally managed to replace the faulty part after all this time. It was/is also the cause of the problem. Still, anyone have another idea?

Slowly, give up...

Could it be the nozzles?

Could also be the fuel pump. Wear > Leakage > Low RPM on starting > Only just the necessary injection pressure is built up.

Please describe the effect in detail again.

Best regards, Lanz

Okay, here's the translation:

So, now, in a point-by-point manner, what's the situation?

Starter turns --> Engine sounds like 'ignition on'
When the key is released, the engine shuts down (sounds like it's not getting fuel or similar). No spark at gasoline cars)
If I hold the key for a longer period AND!!! Full throttle, he usually starts.
Error is sporadic, sometimes the 'ring' also fails quite 'quickly'.

109th new, new glow plugs, ESP timing is correct.
Run length matches
Tension on the EDC is correct.
Okay, I hope I haven't forgotten anything.

Who can help me? VAG-COM available