Please post idle speed for 5-cylinder AEL/AAT engine

Hello Audi A6 TDI (C4) owners,

'I've been experiencing idling problems with my Audi A6 for quite some time, and I've already discussed this in a related thread.' When idling, the engine sputters, but it runs smoothly even with the slightest increase in speed when the accelerator pedal is pressed.

'Until now, I've considered the idle speed to be normal and largely fixed. However, today I saw a higher idle speed on another A6, and it's running smoothly. Therefore, I'd like to know what the correct idle speed is. Please take a quick look at your tachometer, or quickly activate the Climatronic service mode (recirculate + arrow pointing up) and use the +/- buttons to select channel 28, then press recirculate again.' What will be displayed: 70 to 75, or 75 to 80... or something completely different???

As I mentioned, it's about the five-cylinder TDI engine (AEL, or possibly the AAT as a substitute) from the Audi A6. The more people who participate, the better, as I can get a better understanding of the correct value and the acceptable range. Thank you all in advance.

If someone knows the target value from the service manual, that information should not be disregarded .

P.S.: I've noticed a small error in the survey and have adjusted it accordingly. It would be great if you could enter your values there.

Tuppie.

Just under 800 RPM. Analog, no Climatronic.

Hi,

approximately 800 revolutions per minute.
Next time I drive, I will also read the Climatronic code.


A side note, since this concerns AAT/AEL drivers:
When did you need to replace the head gasket on your car?
I now have some oil sludge in my coolant, probably around 165,000 km. The color is no longer quite pink; it's more muted or dull.
The workshop is still refusing the exchange, as this issue is more common in older diesel vehicles.
Only when there is water in the oil should one take action (logically).
How about you?

Hi,
247000, still the first poem. However, unlike me, you also have an oil-water heat exchanger, which can also be leaky.

Hi,

Thank you for your answers.

My current mileage is 319,000 km, and it's the original mileage. Poetry, no signs yet.

'Years ago, I had a 190D. The engine temperature was chronically too high, and it consumed a significant amount of coolant without any visible coolant leaks. I managed to mitigate this by keeping the fan clutch engaged continuously. After about a year, it started developing small oil droplets in the coolant, and since the TÜV (German technical inspection) was due anyway, I sold it.' The mileage was supposedly 200,000 km at the time, but it could be significantly higher.

Tuppie.

PS: Are there any AEL drivers here?

Hi,
The idle speed has consistently been around 800 RPM for years. Read from both the analog instrument and the Climatronic display.
I'm not sure to what extent it's possible to adjust the idle speed via adaptation channels, but it appears that it is being regulated. Logically, the voltage would decrease when a large electrical appliance is turned on (the air conditioner could also simply cause a constant increase); however, it is then automatically adjusted.
I jokingly connected 10 halogen lamps, each 55W, to the jump-start terminal in the engine compartment, as you can see the two-point regulator quite well there. The idle speed initially drops to around 760, then increases to about 820, and then drops back down to 760, and so on.
Perhaps the sawing idle sound is related to a faulty signal regarding the Climatronic system within the Main System Module (MSG).
Is it still active even when you turn off the climate control?

Okay, the head gasket is still the original one (253,000 km), and I haven't seen any oil in the coolant either.

Best regards from Berlin.

Olli.

Hi Olli,

95% of the time, I had the climate control turned off, so it probably wasn't related to that. What I've noticed is that everyone here is stating their idle speed as 800 rpm, which is also what the AEL manual I consulted indicated.

Mine, on the other hand, fluctuates between 700 and 750, and in my last inspection, according to the measurement record, it was 725 rpm, which is significantly lower. Raising the accelerator pedal to 800 rpm eliminates the sawing sound.

Now, the following questions arise:

- Besides the air conditioning, what else can cause the idle speed to decrease?
- Is a stable idle speed of around 700 rpm actually intended and achievable?

The simplest test would probably be to temporarily replace the MSG (Manifold Absolute Pressure sensor), which would effectively adjust the idle setting. 'Just: where is the device located, and where can I get one to test?'

Tuppie.

Tuppie wrote:

Just: where is that part located...?

To the right, in the passenger footwell.

Hi Tuppie,
Please don't be offended, but you can get replacement control units from your trusted local dealer. I once read that the VAG workshops can, for a fee, essentially lend out or provide control units for testing purposes.
However, it doesn't necessarily have to be due to the MSG; it could also be cable connections, connectors, etc.

Best regards from Berlin.

Olli.

@christians

Okay, I'll look for it tomorrow morning. It should be possible to find a solution.

@olli

I don't believe the MSG is defective, at least not in 90% of cases. However, the NVRAM, which stores the idle speed, is likely located within the MSG. Therefore, I believe that a correctly calibrated MSG (Mass Air Flow Sensor) in my Audi should eliminate the error message, which would significantly narrow down the source of the problem.

Hmm, I could have almost guessed that it was the friendly one. The real question is, which workshop actually has that part in stock. I'll probably find out tomorrow.

Tuppie.

Hello,

Analog display:
Exactly 800 RPM, regardless of whether the climate control or other high-power devices are activated; it consistently and reliably regulates to 800 RPM.

Climate control display:
It constantly toggles between 750 and 800 RPM in a 2-second interval.

The first head gasket has already failed. I recently replaced the coolant with G12Plus (due to a thermostat replacement) and the engine oil. Both liquids were stored in separate glass containers, and there were no signs of sedimentation (oil separating from water).

Best regards,

hello,
mine idles at 600 RPM .
There's no noticeable sawing or similar noise, but it's quite obvious that the engine is running too slowly. When I turn on the air conditioning, the whole car shakes. The mechanics at the workshop told me that they couldn't adjust it. I didn't feel like having the entire car checked again and spending a lot of money without getting any results. Unfortunately, I've experienced something like this several times before.
It has been discussed before, but I haven't really understood it . Can the speed be regulated now, or not?
Regards,
Martin.

@Martin119

Welcome to the club, that sounds very familiar to me. Unfortunately, I don't remember my LL (low-speed) RPM from before, but since I've had the car, when the AC is running at low speed, the body has been vibrating slightly to noticeably. Like you, no one could diagnose it, so I just left it as it was. I'm really unhappy with the current state, specifically the idling speed of around 700 rpm.

So, 600 rpm... You really mean two small lines below the 1 on the tachometer? What does the service mode of the Climatronic display show (channel 2, which I prefer to rely on)?

Otherwise, you would almost certainly be driving the same car as the one with your signature.

'I downloaded the complete service manual the day before yesterday, and I've been trying to absorb all the new information since then. The documentation is extremely good, a far cry from the usual 'do-it-yourself' literature that often leads to mistakes. However, especially the relatively inexpensive self-study manual from AAT/AEL, is of absolutely professional school quality, meaning you can actually learn something from it.' I was already afraid that the text was written in the typical IT style: you're not supposed to understand it, and you're not even supposed to try.

So far, there was no idle speed adjustment option in the manual, so I will probably have to address the actual underlying issue... If I find anything specific, it will definitely be posted here.

Tuppie.