Loud Clicking Noise: Causes and Solutions

Hi!

My AKU is sick .

'Especially under partial load, it suddenly develops a severe knocking sound and sounds like an old Ford Transit! Sometimes, if I'm driving with the gear engaged and repeatedly alternate between releasing and pressing the accelerator, the knocking disappears.'

Sometimes, the opposite effect occurs: it's surprisingly quiet, but then it draws very poorly, only to suddenly start drawing again.

Question:

Worn-out nozzles should actually produce a consistent knocking sound, right? Therefore, we can probably rule out the nozzles for now, or?

Could it be that the injection start adjustment is sticking? Is it possible that the injection timing adjuster sometimes gets stuck in the 'early' position and sometimes in the 'late' position?

Could it be that the cables for injection timing adjustment and flow control have loose connections? Perhaps a problem with the pump connector? What type of ESP (Electronic Stability Program) do I have, is it a VP37? What all needs to be disassembled to check the pump connector? Does this connector often have loose connections? Is this a common fault?

More information:
-93,000 km, no engine or fuel injection system failures ever.
- Timing belt replaced at 58,000 km.
- Oil change due in 3000 km, oil level is okay.
- Idle speed normal (no noticeable strong knocking or vibrations).
- No emergency mode detected (no flashing glow plug indicator).
- Sometimes there's a momentary loss of power when starting quickly and engaging the clutch (it almost stalls, but then suddenly recovers with a jolt).

I am grateful for any advice!

cu and greetings.

Hi there!

You'll see the VP37 valve when you remove the cover. However, you can also safely operate the device without it.

Please perform some test runs and compare the actual injection start time with the target injection start time.

"With my machine (model 1Z), a misaligned injection start doesn't manifest as vibrations (otherwise, it should vibrate even at the default setting of 000). You only hear it."

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hello,

I've experienced a similar problem with my VW Transporter (AFN) before! It was characterized by occasional power loss accompanied by loud noises! According to the error memory, the fault code was:
Adjustment for injection start time / Short circuit to ground.

'It was a broken cable! The corresponding cable was actually broken in two places! A replacement kit was available from the dealer for just a few euros! That solved the problem!'

Best regards, Boro.

Hi!

Thanks for the previous suggestions! I'll check all the plugs.

Today, I took a look under the hood and realized that the workshop, about a year ago during a clutch replacement, either forgot or simply omitted some cover clips for cable connectors and plugs. Or was it another workshop two years ago? I should have thoroughly inspected and gotten to know my car when I bought it. It's my own fault. Even better would have been if I had known about this forum back in 2000.

Are the missing cover clips normal?

Okay, and now another question: Why doesn't my EDC trigger an emergency mode (flashing glow plug indicator) despite what seems like serious cable problems? Is a faulty injector control valve or NBF cable, or a stuck injector control valve, not severe enough to warrant an emergency mode?

Best regards,

Hmm, not always does the emergency mode display appear.

Our old 1Z also didn't indicate any emergency mode.

Best regards, WarLord.

Do you mean removing "this" with "Clips"?

http://www.luxus-wg.de/~martin/auto_bilder/clipse_weg.jpg

They can sometimes become self-sufficient. But forgetting is more likely.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hi, there's news about the nail issue.

The knocking sound is now constant, and it's only running at approximately 70 km/h (emergency mode) on a flat surface.

I have performed the following investigations.

-Ignition coil connector disconnected with the engine running -> no change in the knocking sound.
- NBF connector reconnected and connector from the crankshaft position sensor disconnected -> Engine stops with a loud knocking sound, glow plug indicator flashes.
-Resistance of the NBF (Negative Feedback) measured at the connector -> 115 ohms.
- Measured idle voltage at the pulled-out NBF connector (on the EDC side) while the engine is running: 13V.

I combine:

'The fact that the engine stops when the crankshaft position sensor is disconnected suggests that the EDC (Electronic Diesel Control) is not receiving a proper No Bus Found (NBF) signal. With a correct NBF signal, the engine should enter limp-home mode.'
- However, the NBF coil and cable appear to be in good condition (measured at 115 ohms and 13V).

Conclusion:

-Is the inserted NBF connector no longer making contact?
-Is the needle or pressure pin stuck in the nozzle block?


Or am I on the wrong track?

By the way, the timing belt on the camshaft pulley looked okay; there were no signs of wear or fraying.

Next, I'll use my trusty old oscilloscope (even with a 12V power supply ) to capture the NBF signal. Probably not today though.

Eine Frage hätt ich da noch: Wo zum Geier ist die EDC? Ich habe schon die Verkleidung unterm Amaturenbrett und das Handschuhfach entfernt. Die ganzen Hunderter-Relais hängen da rum, aber von EDC keine Spur. HHelp!

Regards,
and I am grateful for any tips or comments!

Hi dieselmartin, no, they were clip-on sleeves for cable connectors and plugs.

I also have some interesting engine bay pictures, but unfortunately I don't have my own web space . Where can I find free web space where I can upload JPEGs and create image URLs?

Thank you for the tips.

Best regards,

Send it over.

Please provide the German text you would like me to translate into English. I will then give you only the translation, without any explanations.

I'll put them over there at my place.

Yes, a naked AKU!!!

The fact that disconnecting the NBF connector doesn't make a difference is highly suspicious and suggests it might be related to that issue.

Bosch offers to restore a nozzle to like-new condition for approximately 80 euros (they offered this to me, and it should also apply to other customers).

The question is whether this will also solve the MBF problem. My question to Bosch was more about the opening pressure and spray pattern (i.e., the injector nozzle).

Do you know what the "Soll" signal looks like from the MBF?

Although it's from a 3.3 TDI common rail engine, it might still be helpful.

http://www.luxus-wg.de/~martin/auto_bilder/Geber1.JPG

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hi Dieselmartin!

I just sent you 5 nude photos from the AKU!

Sure, I know what the NBF signal should look like. Since the NBF is just a coil into which the extended needle dips, you should see pulses on the oscilloscope with half the motor's rotational frequency. The pulse duration should be shorter than 1/4 of the KW period (revolution), depending on the opening time of the needle.

I'm going to take out my EO174 (manufactured in the 1970s with germanium transistors) now .

I will also take a special photo of the oscilloscope waveform for you and the forum, I promise. Unless the needle or pressure pin is really , then the oscilloscope line will remain flat.

Best regards,

Here are the pictures of... what's his name actually?

http://www.luxus-wg.de/~martin/auto_bilder/SeatArosa/

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hi!

Today, I tested the needle valve actuator (NVA). Here are some new findings:

- While the oscilloscope was operating normally and connected in parallel with the NHG (presumably a noise filter), no usable signals were detectable, but there was high-frequency interference voltage, likely caused by grounding through the 12V power supply of the oscilloscope.
- Using a 1.5V battery as the excitation current source and a resistor, weak pulses were detectable, but only sporadically.
-Power circuit interrupted with a pluggable NH fuse: 30mA NH current from the Emergency Disconnection Circuit (EDC).
-Voltage across the NHG in operation: 3.6V.
-confirms the measured NHG resistance of 115 ohms.

Conclusion.

- Everything seems to be okay electrically.
-Is the needle/pressure pin jammed in the injection head, or is the problem located somewhere else?

http://www.luxus-wg.de/~martin/auto_bilder/SeatArosa/Blick%20auf%20NBF-%20und%20KWDWG-Stecker,%20D%fcsenst%f6cke.jpg
Take a look at this photo. The brown connector (on the right edge of the image) is for the NHG (likely referring to a specific component). Directly below it, there's a black, 3-pin connector. On the engine block side, a black, round cable disappears near the bottom of the engine block. That should be the crankshaft position sensor, right? (More photos can be found at dieselmartins link.)

'When I pulled this black connector (3-pin), the engine stopped. However, according to the 'VW 1.9L TDI industrial engine' documentation, with a functioning NHG (presumably referring to an electronic control unit or sensor), it should have continued running in emergency mode.'

Okay, here are the questions:
- Are the previous symptoms considered normal in cases of mechanically defective natural gas engines?
-If the pressure bolt is stuck in the needle holder coil, is the entire needle also stuck, or has the bolt detached from the needle?
- What else could it be?

Thank you in advance for any tips.

Regards,

and thank you, dieselmartin, for posting the links .

Hmm, what seems more likely to me is:

Have you checked the AGR (Abgasrückführung)? The description 'quiet and little exhaust gas recirculation' likely indicates that the AGR valve is fully open, leading to excessive exhaust gases being recirculated.

Hi Julian! The AGR (Abgasrückführung) and the intake manifold flap have been 'defective' for about a year.

The issue with the reduced flow and quiet operation was only at the very beginning and also only occurred rarely after loud 'nailing' sounds. So, it's like the injection control valve briefly felt like giving a late injection .

Now he's just hammering away constantly, of course, in emergency mode.

So, basically, I'd like to know again: Does a DI (dental implant) fail if the injection is started too early, right?

If the quantity control valve sensor had failed, it shouldn't have triggered injection even in emergency mode, because the high-pressure pump and low-pressure injection system would still be functioning and are crucial for initiating the injection process.

Am I correct in assuming that 'nailing' (presumably referring to a problem with the application of something) is always caused by starting the process too early?

Could the start of injection timing adjuster also be the cause? I will measure the voltage at the pump connector. Does anyone have the pinout diagram for the pump connector?

Summary of potential errors:
- NHG (Head-Up Display) mechanically defective (no signal), electrically checked -> OK.
- Injection start adjuster is jammed or there is an electrical fault (contact problem, cable break, etc.).

small survey: How long do typical NHGs usually last? (km)

New fact While idling, I observed some blue smoke and smelled like poorly combusted fuel.

Best regards,

Hi,

I believe no one has written anything about this yet.

Quote:

Eine Frage hätt ich da noch: Wo zum Geier ist die EDC? Ich habe schon die Verkleidung unterm Amaturenbrett und das Handschuhfach entfernt. Die ganzen Hunderter-Relais hängen da rum, aber von EDC keine Spur. HHelp!

Remove the plastic cover above the washer fluid reservoir (directly in front of the windshield, where the wiper motor is located). If it's like on the Ibiza, you should find the EDC module in this area, on the left side.

If you're already there, why not collect the leaves and other debris? The car will appreciate it, and eventually, so will the EDC (Electronic Damper Control) system. Because if the drainage channels are blocked, it can cause the system to fail (this has happened to someone on this forum before).

Best regards,

January.

SeatArosa1.7SDI wrote:

Does anyone have the pinout diagram for the pump plug?

If you have the split connector with one 3-pin connection, that's for the spray nozzle adjuster and the shut-off valve.
When measuring towards the pump, a resistance to ground was detected once, indicating a shut-off mechanism (approximately 10-20 ohms, if I recall correctly). Between the other two pins, there is a fuel injector control valve with a similar resistance value.
So, can you measure the pin configuration yourself?

Quote:

Summary of potential errors: - NHG (Head-Up Display) mechanically defective (no signal), electrically checked -> OK. -The injection start adjuster is jammed or there is an electrical fault (contact problem, cable break, etc.)

I am more inclined towards the latter assumption...