Injector Replacement: When to Do It?

Hi everyone,
I drive an Audi A6 3.0 TDI from 2012 with the 245 hp CDUC engine. The current mileage is 275,000 km.
The engine makes a noticeable rattling sound when accelerating, and there's also a noticeable lack of power.
The error memory is clear.

I've attached a photo here that shows the injector readings at idle with the engine almost warm.

Before I damage the engine by running it with worn or clogged injectors, I'd rather ask a question first...

Cylinder 1 looks good, but cylinder 5 occasionally shows a value of up to 0.27.

Should I exchange them all?

If I understand correctly, based on what I've read here and on the internet, cleaning doesn't really make much sense.

Edit: Brand new Bosch injectors are available for significantly less than 300 euros per piece.
While the action might not be cheap, it's still better than having a broken engine.

Thank you very much for your efforts, and best regards.
Wolfgang.

Hi there.
The values all look good, but number two is a little elevated. If you want to know more about the condition of the injectors, you can check the injector timing correction values.
However, your problem likely stems from a different source. Are the throttle valve and/or swirl flaps in good condition?
hg
Herbert.

Hi Herbert,

Thank you for your reply.

Of course, I'm happy that the values are within the acceptable range.
So, it looks like I still have a lot to read online. Apparently, I misunderstood something about the values.
I'll take a look at the timing correction values and try to understand what they're telling me.

Regarding your question about the valves, I can't answer it for you at the moment. I'm still completely at the beginning stages of investigating the cause.
I'm going to look into the flaps now.
Thank you for the tip.
Due to the harvest season, it might take a few days longer for me to have new information, but I will get back to you then.

Regards,
Wolfgang.

Hi everyone,

I once read out the rail pressure calibration points.

Unfortunately, I can't find any information online about the target values for models 4G and later, so I'm unable to assess those values.

Could someone please give me a very brief assessment of these values?
Sure.

As I mentioned, I'm still looking into the valves and will examine them once I have more information.
At 275,000 km, there's certainly going to be a lot of grime and dirt present.

Here are the values in microseconds:

Injector 1, Rail pressure calibration point 1: -7.70.
Injector 1 Rail pressure calibration point 2 -15.40
Injector 1, Rail pressure calibration point 3: -21.25.

Injector 2, Rail Pressure Calibration Point 1: -1.95
Injector 2, Rail Pressure Calibration Point 2: -11.95
Injector 2, Rail Pressure Calibration Point 3: -15.50.

Injector 3, Rail Pressure Calibration Point 1: -1.05
Injector 3, Rail Pressure Calibration Point 2: -10.10
Injector 3, Rail Pressure Calibration Point 3: -13.50

Injector 4, Rail Pressure Calibration Point 1: -15.35
Injector 4, Rail Pressure Calibration Point 2: -20.80.
Injector 4, Rail Pressure Calibration Point 3: -25.95.

Injector 5, Rail Pressure Calibration Point 1: -2.20
Injector 5, Rail Pressure Calibration Point 2: -12.30
Injector 5, Rail Pressure Calibration Point 3: -21.90.

Injector 6, Rail Pressure Calibration Point 1: 3.95
Injector 6, Rail Pressure Calibration Point 2: -10.70
Injector 6, Rail Pressure Calibration Point 3: -10.55


Thank you very much for your effort, and best regards.
Wolfgang.

Hi,
You can find the entire discussion here: https://community.dieselschrauber.org/en/viewtopic.php?t=28779
According to this, your nozzles would already have quite high correction values at high pressures, meaning they would remain open for too long without any correction.
However, I'm not sure if that's the cause of the problems described.
hg
Herbert.

Hello Herbert,

Thank you for the link. I've entered my values there. So far, no engine with the MKB codes CDUC or CDUD has been listed.

My scores would be terrible even at the 4F level.
I can't find any reference values for my 4G connection that would allow me to make a comparison, but you mentioned that the values in the load range are already quite noticeable.

Nevertheless...
The fact that I intend to take the flaps is undeniable.
I skimmed through some articles about it last night.
Before I invest roughly 1700 euros into the nozzles, I'd like to make sure everything else is okay, and I'd appreciate it if you could share your advice.
Only then does it make sense to ask questions here.

Thank you for your effort.

Regards,
Wolfgang.

Here's what you can do without making a large investment: measure the return flow rates of the injectors, both collectively and individually. The manufacturer provides specifications for the acceptable limits. You'll need the data specifically for the CDUx six-cylinder engine.
hg
Herbert.

Okay, I will definitely also test the return flow rates. It's even possible to do that under the carport.

I had already seen this topic last night.
I will definitely replace the injector that deviates too much from the target value (after checking here ), even if it has nothing to do with the problem or shouldn't be related to it.


Regards,
Wolfgang.