Idle Speed Control: How to Adjust It

Hello everyone,
I recently used VAG-Com to monitor my Audi 80 1.9 TDI (1Z), which has 152,000 km and was manufactured in March 1994, and I noticed some values in group 13 that caught my attention – specifically, the idle speed control.

While idling, I recorded the following values:

Cylinder 4 (Target: -2 to +2) = 4.51 mg/revolution.
Cylinder 2 (Target: -2 to +2) = 1.18 mg/R.
Cylinder 1 (Target: -2 to +2) = 2.55 mg/rotation.

Cylinder 3 is not listed; I suspect that's correct (since the NHG is located there, right?)

What do these deviations from the target values mean, especially since cylinder 4 shows an extreme deviation?

Thank you!

No offense, but the search function sheds light on things! There have been many, many discussions about it.

and cylinder 3 is indeed the NHG!

When I search for "Ruheregelung," I only find one thread... and there's actually nothing interesting in it.

Tino Kossmann wrote:

Cylinder 3 is not listed; I suspect that's correct (since the NHG is located there, right?)

In the VP engine, the third cylinder serves as the reference cylinder and is therefore always equal to zero.

Quote:

What do these deviations from the target values mean, especially since cylinder 4 shows an extreme deviation?

It's normal for your engine to run unevenly.
Why are there discrepancies?
Uneven compression (for whatever reason), uneven spray pattern from the nozzles...

That doesn't sound good at all... I was planning to replace the needle valve anyway. Should I also replace the other injectors at the same time, or is there a cheaper way to do it?

I can't find the threads right away either, but here are a few more points to consider regarding Bertil's comments:

- faulty vibration damper
- Problems caused by uneven running of auxiliary equipment.
- Uneven opening pressure at the nozzles.

Hello, if you want to replace the injector driver, you should at least verschandeln the other injectors and, if necessary, have them repaired. It's best to do this at Bosch.

Do you happen to know approximately how much it costs to get a print?

It depends on the technician; if you're lucky, they might do it for 5 or 10 euros. Otherwise, it's probably closer to 30 euros (assuming the nozzles are removed).