Crankshaft Position Sensor (G28) & Starting Problems

My Audi A3 TDI AGR, manufactured in March 1997, won't start anymore.
Fuel is leaking from the injector lines, but not from the injectors themselves.
The error memory contained only one error code.
00513 Sensor for motor speed, g28.
Implausible signal detected sporadically.
" color="red">Bitte keine Links zu externen Dateihostern! a) nerven die zusätzlich notwendigen Klicks, b) Wartezeit, Werbebanner/Werbepopups und notwendige Registrierungen, c) ist nach einiger Zeit die Datei weg und das Thema für andere Leser nutzlos!

Bitte nutze 'Attachment hinzufügen' bzw. das Upload Forum hier.

Okay, check the MWB 1 module during startup to see if it's activating the pump. If it is, then the problem is likely mechanical in nature.

Timing? Also, even when playing the organ in the MWB 5, check what the NHG is reporting about the injection start time.

Fuel is leaking from the injector lines, but not from the injectors themselves.

Hello,

Could it be that the pump isn't generating enough pressure to open the first stage of the nozzles?

If VAG-Com displays a speed value, then the G28 sensor is also working.

Best regards, Jochen.

Hello!

The same applies to my Passat with the AVF engine. I've already replaced several parts, as mentioned in another thread, but nothing has helped so far! I'm still searching for a solution.
Here's a question for you: When your car cranks, does it sound normal like when it's out of fuel, or is it accompanied by clicking sounds? Does it make a sputtering noise like an old tractor? Mine makes that sputtering noise when starting, but it still doesn't start. After a while, though, it eventually starts and runs normally. The error code in the diagnostic memory is exactly the same as yours, even though it's definitely NOT the G28 sensor! I replaced that one first!

Let me know when you've made more progress.

Greetings.

Here are the things I tried today:

Duesen geprueft > Zwischen 170 und 180 Bar. Spray pattern 1A.

"The measuring device is connected to the fuel injection lines and shows a reading of over 6 bar. This likely indicates that the pressure being measured is just the internal pressure of the pump."

I have reassembled and disassembled the ESP to see if anything went wrong during assembly. It seems that everything was assembled correctly. There are no broken pistons.

Something peculiar caught my attention. Specifically, I inserted a spacer block into the distribution head to simulate a pump cycle. I blocked the check valves to see if pressure would build up. As a result, some pressure did build up.
But, and this was strange, it gurgled out from the opening below the left pressure spring mount.

" color="red">Bitte keine Links zu externen Dateihostern! a) nerven die zusätzlich notwendigen Klicks, b) Wartezeit, Werbebanner/Werbepopups und notwendige Registrierungen, c) ist nach einiger Zeit die Datei weg und das Thema für andere Leser nutzlos!

Bitte nutze 'Attachment hinzufügen' bzw. das Upload Forum hier.

Quote:

What do you think? Am I correct in my theory that if the pump sucks in air, so much that it causes pump failures, this air explodes during the compression stroke of the injection piston? And before the injection piston opens the bore to the fuel lines?! Because normally, a pressure greater than 170-180 bar would then escape through the ESD (Excessive Shut-off Device), if the bore opening were open. Could it be that repeated explosions have created a path to the aforementioned small hole, through which pressure can escape?

"Explosion? More likely an implosion; there could be cavitation damage, but something like that wouldn't just tear through the entire high-pressure section..."


"But, just a quick question on the side: If I remove the ESD (Electronic Stability Device) and possibly also the pressure relief valves, wouldn't the pump still circulate fluid even with zero flow, simply due to the internal pressure within the pump?"
Does the high-pressure chamber still fill with material even when there is no feed rate, as long as the ELAB (presumably a piece of equipment) is open?

So, I'm not yet convinced that this pump was activated during the organ playing, and maybe the problem lies there instead.

Malte1408 wrote:

"Explosion? More likely an implosion; there could be cavitation damage, but something like that wouldn't just tear through the entire high-pressure section..."

That's not likely. But perhaps the pressure damaged a seal or connection.

Malte1408 wrote:

"But, just a quick question on the side: If I remove the ESD (Electronic Stability Device) and possibly also the pressure relief valves, wouldn't the pump still circulate fluid even with zero flow, simply due to the internal pressure within the pump?"

Okay. That's why I also thought that the 6 bar probably corresponds to the internal pressure.

Malte1408 wrote:

Does the high-pressure chamber still fill with material even when there is no feed rate, as long as the ELAB (presumably a piece of equipment) is open?

Okay. I think I can mark the ELAB as complete.

Malte1408 wrote:

So, I'm not yet convinced that this pump was activated while the organ was playing, and maybe the problem lies there.

I don't know what to believe anymore. I've tried so much already.
The magnetic interlocking system appears to be functioning correctly after all the tests.
I believe that my problems might be related to the air intake system.

Quote:

The magnetic interlocking system appears to be functioning correctly after all the tests.

I mean that the problem might not be with the pump itself; it could be perfectly fine, but if it's not being activated, it won't inject anything.

The G28 error doesn't just appear randomly. Diagnostic tools like DZM and VAG-COM are slow, so you might not notice if a signal is occasionally missing. However, the engine control unit (ECU) pays very close attention to these signals.

Even if the sensor is working correctly, there might still be damage to the wiring or its shielding. Or perhaps the sending wheel itself is faulty. (Ultimately, an oscilloscope might be necessary to diagnose the problem.)

Confirming whether the engine control unit (ECU) *wants* to start the engine would have shown a code of either P0341 or P0345 if it was cranking.

...Is it possible to delete the error?

Yes, the error could be deleted without any problems.

And if you used starter fluid spray (yes, I know you're not supposed to),
It started up, but with reduced power in the lower range.
Finally, it started by simply pressing the accelerator and gently lowering the engine speed to idle with the pedal.
I read in another thread that the NHG (presumably a specific device or system) takes over the function of the G28 if the latter fails. And the NHG is not showing any error messages.

Quote:

I read in another thread that the NHG takes over the function of G28 if it fails.

This comes from the SSP (Specific System Program), which allows the NHG (Natural Gas Engine) to use the G28 as an alternative speed signal in case of a failure. In this scenario, the engine continues to run, and only the SB (Selective Catalytic Reduction) system is then controlled.

My EGR valve doesn't do that. It shuts off when you disconnect the G28 sensor, and it won't start again after that.
I can imagine that this function is only activated during driving (speed > 0 km/h) for safety reasons and then deactivates when the vehicle is stationary.

Quote:

And if you used starter fluid spray (yes, I know you're not supposed to), So, it started up, but with reduced power in the lower range.

Quote:

Finally, it would start by simply giving it some gas and gently lowering the engine speed to idle with the accelerator pedal.

Hmm, that sounds more like the pump is no longer able to provide enough fuel. With the starting spray, you essentially bypassed the "lack of influence" on the amount of fuel being delivered during startup.
Then, you might have been able to use the pedal to bring the control system to its maximum setting, at which point the pump would inject enough fuel for the engine to run.

I can also imagine such behavior if, for example, the speed signal is too high. This could happen quickly if some kind of interference is counted as a pulse due to defects in the shielding. }

Have you ever encountered the error message "quantity setting device difference"?
Then either the pump is broken and not actually pumping anything, or the speed signal is distorted and possibly too high.

As I mentioned, the data for MWB 1, including injection quantity, speed, and pump voltage, would be highly valuable for these analyses.

Thank you very much, Malte, for your tireless help .
At least one person is thinking about it.

So, I'm now about 99% sure that the distributor head has a defect.
I have already ordered a distributor head with a 11mm size.
Why not just get a new pump right away? Because the old one has served me well for 282,000 km, and I don't want to have to re-calibrate the engine control unit (ECU).

I have never encountered the "MSW rule difference" error.
Only the nozzle clogging error after the air.

My theory suggesting a faulty cylinder head: The engine is misfiring despite the chip tuning. If the G28 sensor were malfunctioning, it would be able to convert the data from the chip exactly, but within a different RPM range. However, if the fuel injector delivers 20-30% less fuel, while the boost pressure is very high due to the chip tuning, this scenario becomes plausible.
I also believe the error is related to the 600 km driven with air in the system, as it occurred immediately afterward. It could be due to an explosion, cavitation, or simply considering the mileage of the component.
Furthermore, the symptoms would be compensated for by the engine speed if there were a problem with the high-pressure component. When starting, the fuel simply has more time to bypass the injection piston.
Then, with the engine running smoothly, the target exhaust gas oxygen (O2) level is reached very late.

What still surprises me is the function of the small hole on the HD part.
Does anyone know what this is for?

Okay, so the HD part is arriving next week.
If that doesn't help, then a new pump will be installed.
I can now assemble and disassemble things with my eyes closed .

Okay, based on the symptoms, it's not unlikely that at least the high-pressure generation of the pump is malfunctioning.

What I can't seem to get rid of is the G28 error. This error isn't being triggered randomly by the control unit.

The G28 is one of the most important sensors in the EDC system, alongside the G149.

The problem is that the engine speed input to the control unit has a very high sampling rate (the script for the EDC mentions 330 µs).

At idle speed (900 RPM) and with four reference marks, this results in a signal of only 60 Hz. However, the control unit is fast enough to detect brief deviations beyond the possible range between two reference marks, especially if there are 100 "spans" on the encoder disc or if something interferes with the signal line.

"The DZM and VAG-COM would have no chance at all to react. (With the DZM, if it were possible, this would certainly be deliberately prevented, perhaps even before the engine control unit outputs the RPM data)."

The switchgear is likely to react quickly in such a situation.
And if it occasionally jerks back towards zero power after half a rotation because the MSG is applying a speed of 5000 RPM for 5ms, then I can easily imagine that the motor won't start up anymore.

VW itself has commented on the error in the repair manual:

Quote:

00513 Sensor for engine speed - G28, implausible signal. Possible cause of error: - Bent or loose feeder disc. - G28 error. - Interruption of the shielding conductor. Possible effects: - poor starting behavior - uneven engine running, misfires - increased idle speed - Warning light is on. reduced performance - Tachometer not displaying.

Okay everyone. I found some errors .

I'm somehow surprised by how much my theory aligns with the explosions in the high-pressure section.
was was accurate.
After waiting for 3 weeks for the new high-pressure part to arrive, I started to disassemble the large three-sided screw on the pump head. As I held the screw in my hands...
I immediately noticed that something wasn't quite right.
But see for yourselves...

" color="red">Bitte keine Links zu externen Dateihostern! a) nerven die zusätzlich notwendigen Klicks, b) Wartezeit, Werbebanner/Werbepopups und notwendige Registrierungen, c) ist nach einiger Zeit die Datei weg und das Thema für andere Leser nutzlos!

Bitte nutze 'Attachment hinzufügen' bzw. das Upload Forum hier.

Okay, and now I have a pressing question for someone who is knowledgeable about this.
I would really appreciate it if you could respond to me.

Wenn ich den Motor auf OT stelle (mit Nockenwellenlineal), auf welcher Position befindet sich dann die Nut der ESP-Welle: Oben? Unten? Different?

Thank you!