ARL: Stuttering Issues Again?

Hello.

I'm having another problem again.
It's the old problem of stuttering/lagging. And it's happening like this:

I can drive for about 40 kilometers without any problems. Then, it starts to stutter and misfire.
I think it's comparable to the symptoms of "wave-like acceleration."

So far, I've done the following: At 165,000 km, I replaced the injector for cylinder 1. At 170,000 km, I replaced the other three injectors as well. Then, things were good for a while.

Now at 176,000 km, and it's shaking again. I've noticed that after about 5 minutes of being stopped (engine off), it runs well again for a while. I suspect the turbocharger pressure sensor.
Now I've logged a trip and I hope you can help me with my next repair attempts.

AGR disabled.
4 new PDEs.
VTG rods were only checked from above for ease of movement (how easily should they move).
MKB ARL Series.
Year of manufacture: 2001.

Thank you very much.

Best regards, Charly.

- DiFi close.
- Leak in the tandem pump bypass.
- Tandem pump pressure too low.
- The intercooler piping has "flickering" leaks (I've experienced this with 3 units so far).
- "Knackfrosch" (a component) defective on the DiFi (direct injection system) of my own vehicle, which is now causing an imbalance in the thermal management of the injection system.
- ...

Hello.

Thank you for the quick response.
DiFi is almost new. I'll rule it out for now.
Bypass of the tandem pump. Can the pump be disassembled so easily? Without causing any damage?
accommodate any parts.
Druck prüfen. Muss ich mir erstmal was Basteln. I'll do that later.
"The charge air cooler is leaking. Could it be the rubber rings on the pressure lines? Would it be worth replacing them all at the same time?"
"Knackfrosch" - you probably mean valve 1J0 127 247 A. Otherwise, there's something else in the line.
another check valve.

Okay, here's the translation:

Thank you.
Best regards, Charly.

charlyfirpo wrote:

... Can the pump be disassembled easily?

Better not.

Quote:

... Are the rubber rings on the pressure pipes?

Yes and no.
The pipes in the G4 are held in place by the most ridiculous design I've ever seen. The metal clips gradually corrode into the (aluminum!!) mounting points over time. This causes the rubber rings to become loose, and the boost pressure starts to fluctuate.
Cars with over 100,000 kilometers (or miles) on the odometer are particularly prone to these issues.

Quote:

Is it worth it to replace them all at once?

It's not the rubber bands that are the problem!

Quote:

"Knackfrosch" - you probably mean valve 1J0 127 247 A. Otherwise, there's something else in the line. another check valve.

The "Knackfrosch" is the temperature control valve in the return line of the DiFi system.

Yes, I've also noticed that the construction is problematic.

Was kann man machen. Ich habe gesehen das an allen Verbindungen ein wenig Öl zu sehen ist. Sind das schon anzeichen? Wo Öl rauskommt kann ja auch Luft entweichen. Ohe?

New hoses are very expensive. It's just to try and see if that's the problem.

I will definitely trade the "Knackfrosch" (a type of toy).

Best regards, Charly.

charlyfirpo wrote:

Yes, I've also noticed that the construction is negative. What can be done?

... From my side, there's only the "rustic solution" (see below).

Mine was boosting the turbo pressure like crazy, causing a lot of vibrations. After I used zip ties to fix it, it's running smoothly now.

Quote:

I noticed that there's a little bit of oil visible at all the connections. Is this a sign of something? Also, if oil is leaking, it could also mean that air is escaping.

Yes, that too.

Quote:

New hoses are very expensive. It's just to try and see if that's the problem. ...

"The 'rustic' solution has been working for me for 10,000 km..."
For home use, that's enough for me.

Hello.

After a long time, I'm writing again. And I'm still dealing with the same problem.

I have now checked and renewed the following.

DiFi and Knackfrosch -> New.
"Turbocharger pressure system -> Leak detected -> Hose at the coolant outlet identified as defective (worn through) -> Replaced. Additionally, the sealing rings on all pressure lines were also replaced."
Re-sealed -> no leaks detected.

LMM New -> No change.
Duck tandem pump tested.
Fuel pressure at idle speed: 3.5 bar (engine cold), 3 bar (engine warm).
At 1500 RPM, the pressure should be 5 bar (cold) and 4 bar (warm), according to the repair manual, which indicates it is within the acceptable range.
At 4000 RPM, the pressure is 6-7 bar, sometimes fluctuating when the engine is warm.

Please give me a suggestion for what I should try next.
I'm slowly running out of ideas.

Best regards, Charly.

Do you have bubbles coming back in the return line? If so, replace the seals of the pressure equalization device (PDE).
If you have any further questions, please feel free to send me a private message.

Best regards,

The four PDE sensors are all new. I don't think the rings are broken.

I'll check that out regarding the bubbles. I have to go back to work tomorrow, so I only have time on weekends.
I will get back to you once I have verified that.

Best regards, Charly.

charlyfirpo wrote:

at 4000 RPM, 6 - 7 bar, sometimes fluctuating, especially with a warm engine

.

The pressure should be at least 7.5 bar.
According to Repfaden, disconnect the return line.
If the pressure is still below 7.5 bar, replace the tandem pump.
If the pressure exceeds 7.5 bar, replace the O-rings.

Hello Roger,

In the older reference guides, it's written as I described it. In the newest ones, it's written as you wrote it.

I reviewed the service manual for the pump-injector engine, and it describes a pressure relief valve in the tandem pump that limits the pressure to 7.5 bar.

"I have no problem with your statement! It's definitely correct, but doesn't it all contradict itself a little?"

I will follow your advice next weekend, though.

Best regards, Charly.

P.S. I'd be happy to provide the SSP (Service Service Publication) for the PD engine.

Could you please describe the symptoms in more detail? When does this occur? How exactly does the problem manifest itself? Does it also happen at 100% load, or during partial load/idle? Does the car produce black smoke? What is the fuel consumption like? Do you have a log of the injection timing for the common rail injectors? Is the maximum speed reached? What is your charge air temperature (log)? What values are reported by the temperature sensors for coolant and fuel (the latter is located on the fuel rail for the common rail injectors and can cause a wide range of problems if defective)? Has the turbocharger/exhaust manifold been checked for proper seating, oil leaks, soot, or even hairline cracks? Is there anything visible on the cylinder head gasket? What about the timing (timing belt)? When was it last replaced, and have the problems existed since then? Etc. The more detailed you can be in your description, the better we can help you.
And especially when you're creating logs, it's best to always do it from a high idle speed up to approximately 4200 RPM. Record shift times once at idle (both warm and cold), and then also under load (warm only), and at partial load.
"Something else I forgot, what type of fuel is being used?"

Hello.

The error is still occurring exactly as described above.
The log is located there as well. Nothing has changed since then.
The jerking occurs sometimes when the engine is cold, and sometimes only after driving continuously at 60-70 km/h.
Despite this, the performance is still present, and the top speed is still being reached. I can't tell from the rearview mirror whether it's producing more smoke than usual.

There's nothing visible.
Fuel: Diesel (not biodiesel).
Timing belt: replaced at 60,000 km.
Consumption: 5-7 liters.
Temperatures are normal, LLT (Low Level Transmission) up to 40 degrees Celsius. Highway driving at a brisk pace.
The water temperature sensor has just been replaced.
Please continue generating logs from PDE.

Best regards, Charly.

And what about the temperature sensor for the diesel fuel?
"For how many kilometers have you been experiencing these problems?"

Hello.

I've now created a log file containing the timing data for the temperature sensors for diesel, low-level coolant, and engine coolant, as well as the idle speed control system.

The problems have been occurring for about 20,000 kilometers. Currently (yesterday and today, approximately 300 kilometers), there have been no issues.

What about the pump pressure now? According to the repair manual, it's too low.

Should I replace them?

Best regards, Charly.

Okay, I wouldn't worry about your PDE results just yet; all the values are good. While the last PDE value is slightly different, it actually has the best absolute values, so it's probably not a cause for concern.
Furthermore, this indicates that there is no blockage of the magnetic valve and that the fuel supply and fuel quality are satisfactory.
You should create this log again, but over a much longer period. It's possible that different behavior might emerge, perhaps even during the periods of instability, which could reveal something interesting in this area.
What I find particularly striking are the temperatures, especially the charge air temperature.
Du fährst doch einen ARL oder? Is this the original?
I also have an ARL engine, but it's a conversion in a stripped-down Golf 3. The additional oil cooler really helps, and even with the increased power, I'm running the oil temperature about 20 degrees Celsius above the ambient temperature!
"Your nearly 90-degree angle, and the fact that it's constant, is quite surprising to me. Could the LLK (likely referring to a heat sink or cooling element) be clogged externally, or is there perhaps oil or a foreign object inside?"
Temperature sensor defective?
By the way, it's incredibly hot where you are, or is the temperature sensor malfunctioning?
Does the engine stutter even when it's cold? If so, it might help to try a different gas station.
You should also try a test drive without the catalytic converter sometime.

PS: Nicely done logs...