Pump Nozzle Problem AXR - Common Issue?

Hello.

The following problem is about to arise:

While driving on the highway, the A3 engine suddenly starts to stutter for about a minute, then it stops and runs normally as if nothing happened. A few days later, the same thing happens (always while on the highway): it stutters again, but this time it doesn't stop until the engine is turned off. After restarting, everything is fine. When idling, it then runs on only three cylinders (but only when it has previously stuttered). After restarting, everything is okay. The idle speed control is working perfectly.
I read in the forum that there might be a problem with the wiring harness or the connector for the PD (Power Delivery) component.
Can anyone tell me how to access the cables? It seems like I need to remove the valve cover for this. Where are the connectors for the pressure differential (PD) elements?

Here is the error message:

Control unit part number: 038 906 019 FH.
Component and/or version: 1.9L R4 EDC 0000SG 1544.

Two error codes found:
18074 - Valve for pump/nozzle cylinder 1 (N240): electrical fault in the circuit.
P1666 - 35-10 - - - Intermittent.
16685 - Cylinder 1: Misfire detected.
P0301 - 35-10 - - - Intermittent/Sporadic.

Thank you for your suggestions.

When you're standing in front of the engine, on the right side near the spark plug, just before the coolant hoses, there's a fairly large, round connector. The PD (piezo injector) elements are connected to it. I would start by checking that. If that doesn't solve the problem, and the wiring harness leading to the MSG (Engine Control Module) is in good condition, you'll need to open the valve cover. Underneath, there's a rail that has a connector for each PD.

Okay, great, thanks. I can start working on it tonight.
I'll get back to you later.

Save yourself the hassle and replace the wiring harness from the connector onwards. It doesn't cost much, and it's a known source of problems. I had this issue with my aunt's car. Although the contacts looked fine, the problem was still due to the wiring harness...

And it's not even that expensive...

cksIT wrote:

Save yourself the stress and replace the wiring harness from the connector onwards. It doesn't cost much and is a known source of errors. I had this problem with my aunt's car. Although the contacts looked good, it was still due to the wiring harness... and it's not that expensive either...

Wiring harness: From where to where? From the PD elements to the round connector that Matthias explained to me?

I'm sorry, but I couldn't look at the car yesterday; I had to reschedule. However, it seems to be getting worse every day.

Basically, it's the wiring harness located under the valve cover.

Okay, thank you.

cksIT wrote:

Save yourself the hassle and replace the wiring harness from the connector onwards.

Right, and it can even be found using the search function.

I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

Quote:

It doesn't cost much and is a well-known source of errors.

Please provide the German text you would like me to translate into English. I will then make the requested change ("kostet nicht viel" to "kostet leider viel") and provide only the translated text.

1/4k€ for a pair of cables and connectors is quite expensive...

No, this is available as a separate item: part number 038971600 for €41.88.

That's definitely possible.

Thank you everyone, the problem is solved.
I replaced the wiring harness with part number 038971600, and now the car has been running perfectly since Sunday.
- For those who don't know what this is about, like I did a week ago: This refers to the 'harness' that is located inside the engine. It plugs in sideways into the cylinder head and has a round connector on the outside; internally, it supplies power to the four PD (common rail) injectors.

Thank you again.

mserge wrote:

I replaced the wiring harness with the number 038971600, and now the car is running perfectly again since Sunday.

Great .

Now it would be interesting to measure the old wiring harness to pinpoint where the problem lies (e.g., by passing a few amps through each wire while moving the harness and measuring the voltage drop).

Perhaps this will help us identify the design flaw...

Hello, I was on vacation.
Unfortunately, I've already thrown that part away.
Regarding a design flaw, as I see it, the cables and connectors that are installed in the oil (which are not protected and exposed to the cylinder head oil) are subject to oil flowing over them and reaching the connectors of the PD elements. This leads me to wonder why it worked for so long. The strange thing is that sometimes it worked, and sometimes it didn't.
The wires had also become quite hard.

Hello!
Does anyone know approximately how long a "wiring harness fault" needs to occur before the error is logged in the memory?

Best regards,

The time interval is variable. As soon as communication breaks down, which happens even with the shortest interruption, errors occur.

The entire construction is quite delicate and, as you can see, unfortunately prone to errors...

@Mike3BG

Initially, when it only occasionally glitched, there was no error in the memory.
The error code didn't appear until he stopped accelerating erratically on the highway and the engine started running rough even when idling, indicating it was only firing on three cylinders.

Interesting! Because I'm also still looking for the cause of my startup problem. That could possibly be related to it. So that's my question: if the error immediately goes into memory, then I can rule that out in my case, because I've never seen that specific error message. Apparently, the "PD cable problem" has to occur for a relatively long time (i.e., > 8 seconds) before it gets written to the memory. Can anyone confirm this?

Kann man den Kabelsatz einfach tauschen, oder muß da unbedingt der ran? Ich habe mal wo gelesen daß die Zylinderkopfhaube/Abdeckung wegen der nicht einzeln kaufbaren Dichtung komplett getauscht werden muß? StWhat does that mean?

Thank you.

Greetings.