Piezo Injector Test: Audi A6 4F Diagnosis

Hello everyone!

'My V6 engine isn't running smoothly; apparently, there's no compression in two of the cylinders. It's actually only running on four cylinders now, and a huge amount of finely atomized diesel is coming out of the exhaust. My initial thought was that the injectors might be faulty (crumbling, as I read in another forum). I've already removed the injectors from cylinders 1-3, and they look brand new, which of course doesn't necessarily mean anything. I cleaned the parts with brake cleaner and carefully wiped away any deposits with a soft cloth.'

Is it possible to inspect and, if necessary, repair such injectors, similar to how gasoline injectors are checked?

Best regards!

Frank.

"Tell me something about the year of manufacture, engine code, etc."

What is the manufacturer of these injectors? If it's BOSCH, it's worth contacting a larger BOSCH service center, preferably one that specializes in fuel injection systems. There should be a BOSCH service center near you that can test the parts to determine their functionality, and if necessary, adjust or repair them.

But I think that not many people are truly competent to provide real help with CR technology.

From my perspective, I recommend this service provider; they will definitely be able to help you.

http://www.blumentritt-petersen.de

You could also try contacting Rainer (diesel mechanic), and the boss will surely be able to offer advice as well.

Hi,

If even a small amount of fuel is getting into the cylinders, as indicated by the fuel smell coming from the exhaust, then those cylinders definitely no longer have compression. There's not much you need to check or think about in that case.

Best regards, Rainer.

Okay, so the next question is under what circumstances the diesel is being injected. Isn't it possible that the injector is simply defective in such a way that the fuel is being sent in at the wrong time? Can injectors "drip," like worn-out VP nozzles?

I think it's quite unlikely that two cylinders would lose pressure at the same time, right?
"Unless they are lying on their side, in which case it would primarily indicate a problem with the valve mechanism (valve, nozzle, etc.)."

I would be surprised if a CR (presumably referring to a combustion engine) with a hanging nozzle would even start.

It would have been interesting to see the return quantities, but if they're already out there...

Connect the compression tester and then see what the results are.

Hi,

If even a small amount of fuel is getting into the cylinders, as indicated by the fuel smell coming from the exhaust, then those cylinders definitely no longer have compression. There's not much you need to check or think about in that case.

Best regards, Rainer

Hello Rainer!

According to the workshop, two cylinders have no compression: cylinder 1 and cylinder 5, one on the right and one on the left. Since I haven't removed the cylinder heads yet, I can't say for sure what the cause is, but I suspect there are holes in the pistons. I still had a glimmer of hope that the injectors were so defective that they were essentially flooding the engine with fuel.

Now it's clear that a major overhaul is needed. However, I still want to be on the safe side regarding the injectors and have them checked. It would be a shame if I installed those parts in the rebuilt engine and it failed immediately.

@ everyone, does anyone have any more addresses of companies or individuals who can inspect these parts?

Best regards!

Frank.

Edit: I'm taking my injectors to a Bosch service center in KA, where they will inspect the parts and, if necessary, repair them. Afterwards, I (hopefully) will be wiser about why the machine failed.

Frank F. wrote:

I still had a glimmer of hope that the injectors were so defective that they were essentially drowning the engine in fuel.

It's simply not possible. Diesel is oil, which also provides a seal. Gasoline washes away the oil film and causes the compression to decrease.

P.S. I told you right away that you shouldn't remove the injectors, but rather remove the glow plugs. Now you know exactly as much as you did before.

Compression test in "Russian" (you can do it ):

- Oil filler cap on.
- Disconnect the intake hose.
- Set the injection timing to Top Dead Center (TDC) for the relevant cylinder (with the valves closed).
- Use a suitable compressed air gun to blow air into the bore (spark plug hole or injector) of the cylinder in question.

- Listen/feel to see where the noise is coming from the most (oil filler cap, intake manifold, exhaust).
- If possible, compare it to a "healthy" cylinder to identify any differences.

It may be necessary for an assistant to hold the crankshaft in place if the cylinder in question is not precisely at top dead center (TDC).

It doesn't cost anything, but then you'll know more .

Quote:

It may be necessary for an assistant to hold the crankshaft in place if the cylinder in question is not exactly at TDC.

Caution: Risk of injury! Preferably, secure the workpiece with a vise ("Gang rein" is a German term for a type of vise) and avoid using your fingers to manipulate the belt drive.

Well, they probably don't have 18 bar pressure .

1 bar is approximately 1 kg/cm ² , the piston has an area of approximately 50 cm ² , which means that at 10 bar, a force of 500 kg pushes it downwards.

I don't want to put my finger in the wrong place.

Irony on: My dear, you are of course absolutely right, in principle!

...but only under the condition that the whole thing is a closed system. But thankfully, pressure spreads in all directions . And since some valve is already open, it will be difficult with 500 kg.

Quote:

And some valve is already open

.
It won't help the poor piglet whose fingers were pinched off after a quarter turn. Well, what am I saying? Some people just put their fingers in the wrong place and then let 10 bar of pressure through the GK/injector opening. After all, the saying goes, "If you don't want to listen, you have to feel."

Oh, so you mean! I think he probably meant "securing" something, using a tool to secure it!

'Anyone who has ever smacked a key off their flipper because it bounced back.'
and that's just for a small 1-liter gasoline engine, and they know that's the case.
You can make acquaintances with the nursing staff at the local university hospital, completely free of charge .

Hello everyone!

Yes, Russian testing methods are usually simple and effective, but not always completely harmless . However, considering all the symptoms (running on 4 cylinders, the workshop says there's no compression, fine mist of fuel coming from the exhaust), it doesn't really matter which test is used. What I'm more interested in is the cause, and to find that, the engine needs to be opened.

I've now sent the injectors to the Bosch service center, hopefully they're competent. I'll get the results this afternoon.

Best regards!

Frank.