New nozzles! Why is the engine running rough at low RPM?

Hello, I swapped the injectors (0.185) on the ALH engine with the injectors from the ASV (0.205). AGR is "broken" otherwise everything is untuned and stock.
After the nozzle modification, a significant increase in performance is observed.

Unfortunately, I'm now experiencing significant (and previously non-existent!) hair growth, some of which is visible in the rearview mirror.
The rattling sound typically occurs at lower RPMs, up to around 2000 RPM.
Once the boost pressure is present and regulated, the Russian engine's emissions are minimal, which can be explained by the lower boost pressure (0.1 bar) compared to the ASV engine.

I know that the 90hp engine control unit (ECU) from the ALH engine injects slightly more diesel through the injectors at lower RPMs compared to the 110hp ECU from the ASV engine. However, the difference (in my opinion) is too small to cause the excessive black smoke that some people experience.
I've seen other Golf IVs with the same 90 horsepower engine that had their injectors upgraded to 110 horsepower injectors, and they didn't experience any or only minimal knocking.

What could be the reason for this, and what should be done?

Hello,

Will the injection start be properly regulated even at low engine speeds?
Settings controlled?

Best regards, Rainer.

Hello,

What's the best way to monitor this? VAGCOM is available, but I'm not quite proficient with it yet... I can also log data, but I need to know which blocks to select. The computer is slow and reaches its limits with too much data.
Sure, no problem!

PS: I only need to adjust the injection start time if the opening pressure changes, right? "In my opinion, however, mine are always 220 bar."

If TDIs with stock engines produce a lot of soot, it's usually due to leaks in the intake manifold between the turbocharger and the engine, and/or a malfunctioning EGR valve that isn't closing properly.

Problems at the "light" level might still go unnoticed without tuning, and only become apparent after tuning -> also look in that direction.

Hello Ulf,

So, you're saying I might have a leak somewhere... meaning the air that's supposed to be burned isn't getting into the combustion chamber, and therefore it's missing during combustion => resulting in soot.
Okay, that makes sense. However, this effect should mainly occur when there's boost pressure, which isn't the case for me... I'll still take a look and see if I can find anything.

Quote:

PS: I only need to adjust the injection start

if the opening pressure changes, right? IMHO, but in my case, they are each 220 bar.

You're right...

Marzocchi wrote:

PS: I only need to adjust the injection start time if the opening pressure changes, right? IMHO, but in my case, they are each 220 bar.

It depends on the condition of the old nozzles or what they were like during the last timing belt replacement.

Marzocchi wrote:

The rattling sound from the Russian car primarily occurs at lower RPMs, up to 2000 RPM. Bitte gib den Text an, den du übersetzt haben möchtest. however, this effect should mainly occur when there is boost pressure, which is not the case for me...

Even at speeds below 2000 rpm, there can already be significant pressure – and something seems to be "different" about your engine.

Quote:

I've seen other Golf IVs with 90 horsepower that have received 110 horsepower injectors - and they haven't knocked at all, or have had only minimal knocking

.

Hello,

Okay, I've checked everything again, but I can't find any leaks, no matter how hard I try. I even deactivated my LDA and removed the pin that I used to tap into the hose before the EGR valve, and I sealed the hole.
That wasn't the problem. My LMM (likely referring to a Lambda Maximum Model or similar) wasn't performing optimally, so I replaced it just to be sure, but (as expected) it didn't make any difference...

I'm slowly losing hope. What else could it be?

My timing belt was replaced by VW approximately 14,000 km ago. Could they have made any changes to the injection timing during the replacement? What can I check there?
Thank you for your help!

Marzocchi wrote:

My timing belt was replaced by VW approximately 14,000 km ago. Could they have changed anything regarding the injection timing? What can I check there? Thank you for your help!

Here's a hot tip:
Browse the articles!

Hello,

I've done some research... I'll check the fuel injection timing later.
Is there a diagram available for the ALH engine?
Could it make sense to reduce the injection amount to 2.5 mg/h?
Best regards,
Bernd

Marzocchi wrote:

Would it make sense to reduce the injection amount to 2.5 mg/h?

If you're referring to the displayed idle speed:
No. If you're going to mess around with it, you should increase that amount instead.

Hi!
Have you actually checked if the new nozzles are properly seated? I mean, whether compression pressure is being lost due to a misaligned or unclean seal? Because if that's the case, compressed air can escape, leading to incomplete combustion. Just try putting some oil on the nozzle base and running the engine (or... Release gas and check for escaping bubbles.
Sure, here's the translation:

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which translates to "Sincerely" or "Best regards" in English.

Hello,

I just checked to see if the nozzles are properly seated. On one nozzle holder, I noticed some small bubbles. I loosened the pole again and then tightened it back up.
Now all four are sealed, but it didn't make a difference.

The bridge for the glow plugs wasn't properly seated either. But that has nothing to do with it.

I tried activating and deactivating the AGR (Abgasrückführung), but it doesn't seem to affect the engine's running behavior at all.

I've checked the injection timing: Channel 2 = 44; Channel 9 = 105. I don't have a table for the ALH engine, but it should be correct, right?

I'm really at a loss for words.

Hello again...

I'm currently browsing through my "Do-it-yourself" book for my Golf IV and I've reached the "Problems and Solutions" section for the diesel injection system.
The problem description states: "Black smoke (after start)." A suggested solution is: "Faulty coolant temperature sensor or supply line." While I don't observe excessive smoke when starting the engine, VAGCOM indicates an error related to this sensor when reading the error codes from the instrument cluster.
The water temperature gauge in my car is behaving normally, so I've never really worried about it. Do you think it might be related?

No, the initial amount doesn't matter when driving.