Injector Cleaning: VW/Audi Diesel Engines

Hello,

Has anyone ever treated a faulty ultrasonic transducer in an ultrasonic cleaning bath using an appropriate cleaning solution?

After a long search, I found a company that offers cleaning agents for injector valves.
http://www.bandelin.com/datenblaetter/tickopur/r61_8378.pdf

And just today, my wife Faru called me because our Passat (model years 1996 and 1Z) is experiencing some issues.

Question: Can a needle injector be refurbished, or is it necessary to purchase a replacement part?

Thank you and best regards,
Dietmar

Hi.

Here are a few random notes:

- First, figure out where these problems are coming from - is it really the NHG?
- The carbon deposits are located on the OUTSIDE of the nozzles, making them easily accessible for cleaning with a US-Bad (cleaning system).
- The NHG (Nitrogen Humidification Generator) is located INSIDE the nozzle, so it's not easily accessible.
"NHG defects are (as far as I know) not caused by 'dirt' (and a cracked pane of glass cannot be repaired by cleaning)."

Depending on the mileage, I would prefer to buy completely "new" injectors – for example, having the Bosch injectors refurbished.

m;

"How is the needle lift mechanism constructed? I think I read that the needle is simply longer than the needles in the other nozzles and dips into a coil. In that case, it seems like only the coil could break, right?"

It could be related to the coil. If the oscillations are being attenuated inductively.
I'm familiar with the problem of the ABS sensors, which sometimes fail intermittently due to loose connections in the coil. The wire used there has a diameter of approximately 0.1 mm.
But conversely, if Bosch can overhaul it, would they also install a new coil?

The BOSCH refurbishment referred to the actual injector nozzle.

If the NHG (presumably a type of insulation) is damaged, it will probably need to be replaced (but I would also have the other three replaced at the same time).

m,

If I keep thinking about it, it might be possible to knock this ceramic piece off (I suspect the coil is directly underneath), wrap a new coil around it, and then somehow reseal it.

Does anyone know the exact structure of a German "NHG" (presumably referring to a specific type of document or organization)?

counter-question: what should you do if the needle feels stiff or difficult to move?
In my opinion, this is the main reason for defective NHGs.

'While tinkering with the coil might seem appealing, it's not very practical. I once tried something similar with a coil for a solenoid valve on an Isuzu Trooper. It worked for a while, but then caused major problems. With the experience I gained back then, I wouldn't do it again... The NHG parts aren't exactly cheap, but I think replacing the entire unit is the cleanest solution.'
The injectors already have around 150,000 km or more on them, so it's probably worth replacing the entire set!

...assuming it's the NHG!

joergs wrote:

Counter-question: what should you do if the needle moves jerkily? In my opinion, this is the main reason for defective NGs.

I have been assuming so far that the problem is electrical.

If you unscrew the nozzle head, you can easily remove the needle and clean it.
Or am I completely wrong if I imagine that the needle is simply longer?

Remove and clean.

Hey! And how do you reset the opening pressure then?

Okay, never mind! Bosch routinely and extensively reconditions parts in large quantities. They know what they're doing. With older diesel engines, it's relatively simple to recondition the injectors themselves with the right techniques. However, with direct injection systems that have two spring-loaded injector holder combinations, it's not quite so straightforward.

The simplest and safest solution in such a case: purchase replacement nozzles... everything else is just a temporary fix.

Also, a jammed or skipping needle is not necessarily the cause of contamination. Wear and tear also plays a significant role.

You're probably right.
Interestingly, the Bosch service replaced the remaining 3 injectors on-site, but not the NHG (presumably a specific component). There's probably a good reason for that.

Does anyone know the exact structure of an NHG??

Yes, but what you're referring to is an NBF.
BIG difference

Forget about repairs!

CU Gremlin.

A needle lifter and a needle movement sensor are not the same thing??? I thought they were just different names for the same thing.

Hello everyone!

Since Bosch no longer offers replacement nozzles, at least for my AHF model, I've decided to replace the nozzle heads.

Cost item: 4 print heads for 160 euros at the Bosch service center .
3x nozzle block + NBF, approximately 800-900 Euros

Cleaned the old nozzle bodies, screwed them back on, paying meticulous attention to cleanliness, replaced the nozzle heads, and then reassembled everything in reverse order!
Tighten the nozzle retaining screw to 80-90 Nm. Also, use new heat shield gaskets.
I then took the car to a Bosch service center to have the injectors tested, and lo and behold, all 4 were measuring almost exactly 195 bar, and that after 215,000 kilometers!
The Bosch technician mentioned that the NBF (presumably a specific component) should not be disassembled, as it would then be electrically defective !
'In my opinion, this is just a way to make money, because I'm not disassembling the entire fuel injector, I'm just removing the old nozzle and installing a new one – that's it!'
Nothing is adjusted regarding the anchor or spool settings.

The difference is enormous; it starts up again with the first revolutions, reaches its maximum speed again, and no longer smells like my old turbocharged diesel!

I highly recommend it to anyone who feels confident enough to tackle this project themselves; I saved a lot of money and learned something new in the process!

Best regards, Ferdi.

Did you replace the entire needles, or just the tips?

Does the AHF actually have nozzles with a pressure rating of 190 or 220 bar?

m;

A needle lift injector and a needle movement sensor are not the same thing??? I thought that was just another name for it.

No, that should be taken literally.

NHG (Needle Height Gauges) are primarily used during the development phase to measure the actual needle stroke in order to determine the injection molding process. They operate either inductively (using a bridge circuit) or with Hall sensors.

NBF simply detects the movement of the needle.

@ferdi
What you did was replace the blocked nozzles. That makes perfect sense.
Only if the NBF (presumably a specific component) has an electrical defect, the coil is faulty, or there's something stuck in the upper part, you might be in a relatively difficult situation.

CU Gremlin.