Bitte um Hilfe: Passat AJM ruckelt

Hello everyone. I have been a long-time reader of the posts on this forum, and now I am writing my first post. I hope that I have not violated any forum rules.
I have, among other things, a Passat Variant AJM, manufactured in 1999, with 198,000 km, nothing has been modified, everything is original, all intervals and inspections have been carried out. It only runs on tank-station diesel, nothing organic. The car has been jerking for 4 months and is not reaching its performance. The engine sounds absolutely quiet, starts immediately, and does not stall. The jerking only occurs under load; if no gas is given, nothing is noticed. The consumption is around 6 liters. Only in the morning, immediately upon starting, a dark cloud appears. I have a VAG-COM system from the manufacturer and the VAG manuals for this car. All values are in the green, and the memory is empty. Perhaps someone can help me and tell me which data blocks I can log and help me with the evaluation?

So far, the following have been tried without success:

LMM (several brands tried, Bosch and Pierburg),
Air filters,
Fuel filter together with the cooling unit together with all fuel hoses,
Tandempump
Coolant sensor, Engine temperature sensor, Intake air temperature sensor,
AGR Valve, Magnetic Valve for Charge Pressure, Magnetic Valve for Actuation of Suction Valve
Turbocharger,
PD Cable, 0-ring PD units,
The fuel pump in the tank has been retrofitted with a filter in the tank (Everything was prepped, pump and relay installed and working, OEM did not have one)
All vacuum hoses

So far, the following has also been done:
ZR Setting Checked
Drove without a cat (when the cat was removed, it sounded like misfires while driving)
Turnstile entrance cleaned

Now I want to tackle the PD Element next. However, since this is very expensive, I would like to ask first if one of the experts can confirm that my approach is correct. I am requesting assistance.
Steffen

Hello Steffen,

Please check if the bus network is free of interference, e.g., using an oscilloscope etc.

For example, I once had a situation where a faulty fuse box for the fans caused so many malfunctions that the car could only travel 100 km at full speed with constant jerks (presumably from the engine control unit?).

No defects were detected in the engine or engine control unit and wiring. After replacing the burnt-out fuse, all other problems were resolved.

Otherwise, check block 13 (idle speed control) and 18 (static PD elements) in the engine control unit.

Best regards, Rainer

Hello Rainer,
Thank you for your response. I would like to check the wiring harness. I just don't know how. Not yet. Is it possible with the VAG-COM? There are buttons on the control units that say "wiring harness", but the vehicle doesn't respond. I also don't know if the old Passat needs to be able to communicate with it via an interface.

The MWB 18 shows 4 zeros at idle. The MWB 13 shows deviations of max 0.45 mg/h. Except immediately after a cold start, the values are 1.36 mg/h on cylinder 1.

I logged MW 13 and 23 this morning while driving to the bakery with a cold engine, and I'm trying to upload the file later. With MWB 23, cylinder 4 consistently shows high values around 80. Cylinder 3 is usually around 50-60, and the other two are around 20. Unfortunately, I haven't found any literature regarding the target values for AJM on cylinder 23.

I would also be very interested in having all the cable harnesses associated with it measured. Therefore, I am looking for a VAG 1598/31. If anyone has one for sale, I am interested.

Sometimes things go wrong in a silly way. I heard about a Sharan that was completely unusable. Nothing worked at all. The cause was a faulty, heated washer nozzle. You really have to be aware of things like that.

Here is the log file. The first time, I hope I have done everything correctly.

/viewtopic.php?p=136364#136364

Hi,

Quote:

Please check if the bus network is free from interference, e.g., using an oscilloscope etc.

This cannot be done through a diagnostic system.

Measurement block 13 and 18 are probably okay... too bad.

Is the power supply to the engine control unit (ECU) okay? If logs are failing, that would be an indication that something is wrong.

Best regards, Rainer

MWB 13 has only minor deviations of max 0.45 mg. MWB 18 contains all zeros. I will also make a log tomorrow.
Logs do not terminate.
The diagnostic system is running smoothly. The car is not simply stalling or running unevenly. It is jerking and lacks power. And this only occurs under load. If you don't press the accelerator, you don't notice anything. It is also not smoking and there are no unusual noises. It starts immediately.
Sometimes it's a little better, and then again it's worse.
I also noticed some issues with the PD seats. I saw this when I was changing the 0-rings.

Yesterday, while troubleshooting, I connected our Sharan ASZ (new head with 4 new PDEs) to my laptop. The MWB 23 shows everything as close to zero. It fluctuates by about 10 points up and down.

My Passat has: Cylinder 1-20, Cylinder 2-35, Cylinder 3-65, Cylinder 4-45

The compression is 35 bar consistently across all cylinders. Differences are 0.5 bar or less.

But: just now I measured the pressure of the tandem pump: it shows 3 bar at idle and the needle fluctuates slightly by half a bar. At 1500 RPM (engine cold), the needle jitters between 3 and 8 bar. And it's doing so wildly.
Can anyone tell me anything about this? Does the engine need to be warm? Do I need a different gauge with a glycerine filling, perhaps? Am I doing something wrong?
Or does the Passat need a new head on its old age? Or are it "just" the PDEs?

The replacement fuel pump is new (Pierburg) and the 0-rings from PDE are also new (Bosch). I have experience with the placement of the 0-rings above the 0-rings, pointing towards the fuel rail, on all 4 cylinders. The car has 200,000 km on it.

Need expert assistance!

Hi,

Okay, here's the translation:

Please, inspect the fuel lines using transparent hoses and look for air or foam.

Best regards, Rainer

It was the manometer. I installed one from a well-known manufacturer with a glycerine filling today, and it had clear, readable values:
3 bar at idle (820 Umin in my case)
6 bar already at 2000 RPM
and 9 bar at 4000 RPM


This is more than sufficient. I can also mark this as complete.

Take a good look at your swing arm pivot.
Especially at the front and back, to check if the closure stoppers are still present.

Thank you for the tip. I've ordered 2 new PDEs and still need to get the expansion screws and new pressure screws for the valves from VW, and I'll start with cylinders 3 and 4. And while I'm at it, I'll also take a look at the shafts and the valve mechanism. I'm not sure right now what the "closure plugs" are referring to, but I'll definitely find out when I remove the part.

If you look at the faces of the axes, you'll immediately see what I mean.

Thank you, I really appreciate it. I'll keep you updated. I'm probably not going to install the injectors until November because I have a week of vacation. And also, I'm thinking about replacing all 4 at the same time since I'm planning on doing a lot of mileage. With 2 new and 2 old injectors, it definitely won't run very smoothly. But I'm sure I'll find the problem! I've already replaced half the engine.

So, I don't think you'll notice anything different in the engine performance if you only install 'just' 2 new nozzles, because it's already quite expensive. You're basically spending 800,-€. The PDE is just being replaced in the workshop, and even though it's defective, the engine still runs smoothly. You definitely won't have any problems. OK, 4 new PDEs is definitely a good investment, but whether it's necessary is another question. What does a set of PDE (4 pieces) actually cost when exchanging them at VW? It must be cheaper than 1700,-€, right?

Best regards

I don't know what they cost at VW. We still have a Sharan ASZ that the dealer had to replace several times under warranty. At that time, the price was mentioned to be around 600 euros each.

But let's get back to the Passat, it has 200,000 miles on the odometer and the injectors have given up. They're still in there, and they've never had any problems. I want to replace them all at once, and I only want to do the repair once.
I can't verify the spray pattern because I don't have the equipment. And even if I did, I would still have to remove the PDE; the work would be the same.

The Passat injectors can be ordered for Bosch's use in a replacement. I have already ordered 2, but I was considering ordering the other 2 as well. I work as a parts sales representative for a well-known German wholesaler. I'm not sure if I can include the name here, so I'll leave it out. The price is much further away from 600 euros per piece.
But it's still expensive, you're right. Especially when you see the list of everything I've had to replace. And then it's a 9-year-old Passat.
The coupling with the ZMS was replaced last year. I can never sell the car .

He's back and performing incredibly well. After many months.
I replaced all 4 PDIs today, along with the adjustment valves and all the screws. After that, the jerking stopped and the engine was running smoothly again. However, the idle was very rough. The PDI in cylinder 1 had 2.99 mg of extra fuel for idle stability. I then re-checked all the settings (180 degrees and right-angle installation) and measured the resistance between the contacts and the incoming voltage, but everything was fine.
Then I had no choice but to reinstall the ones with the best values from the old ones into Cylinder 1. With the old rubber rings and bleeding hearts. Now I have 3 beautiful silver spray nozzles and one that is completely burnt out. I now have 3 nozzles with the AK (PDE1.3/80/465S38) from AUY and one with the T (PDE 1.3/80/465S35) end.
"Absolutely no way," I thought when assembling it. But the results were surprising; the engine control unit settings were correct, and the engine is now running perfectly smoothly and very well. It's revving up over 3000 RPM, which is amazing, especially considering it's an AJM engine. I can't even remember how it used to run. Now it's running almost as well as our Sharan ASZ (at least, that's how it feels). Fortunately, the adjustments to the cylinder head didn't turn out to be a problem as I initially feared.
And the exhaust fumes also don't smell like those of an old LT 28 transporter anymore. This is probably due to the fact that the fuel is now being atomized properly again.


Would you like the 4th? "Should I still change the PDE even though the engine is running, just to ensure everything is the same? But then there's also the risk that the M6 thread on the clamping plate could come loose. This screw is really 'hot'."