AEL Engine: Idle Airflow Control Measurement

Hello,

Can anyone provide information or guidance that explains measurement group 013 in more detail?
The replication guide itself does not mention this, and neither does any other literature I have consulted address this specific set of measurements.
I would like to know what it means, for example, when everyone is in the negative, when everyone is in the positive, when there is an outlier, what a large difference in values signifies, etc.


My values are:

Abweichung von Zyl 5 zu 4 -0.43 mg/R ( 1. Block.

Abweichung von Zyl 3 zu 4 -0.16 mg/R ( 2. Block)

Abweichung von Zyl 1 zu 4 -0.31 mg/R ( 3. Block)

Abweichung von Zyl 2 zu 4 -0.63 mg/R ( 4. Block)

(Engine temperature: 90 degrees, Ambient temperature: 12 degrees)

I would be grateful for answers, suggestions, helpful literature references, and links.


Best regards,
Kristian

Based on the readings you've provided, the measurements appear to be perfectly normal. I've been deeply involved with the diagnosis of the AEL system in recent months, particularly focusing on the MB 13, and here are my findings:

- The engine control unit (ECU) determines the amount of fuel injection needed for optimal idle speed based on fluctuations in engine speed.
- Control is achieved by varying the MSW signal.
- The values can range from +4mg to -4mg.
- Significant deviations are observed with faulty fuel injectors, and typically, the defective injector is the next one in the firing order after the injector with the abnormal reading.
- Extremely high deviations are observed with defective or contaminated measurement systems, typically 2 units at the positive limit and 2 units at the negative limit.

If the measured values do not change when ESD is triggered, it is likely a problem with the MSW (Main Switching Unit) of the ESP (Electrostatic Precipitator).

>>> But your values are absolutely fine. If there's a problem, it must be somewhere else.

I also own an A6 with an AEL engine, and since I started handling the service and repairs myself, I'm completely satisfied with it again. I only had problems and unnecessary expenses with workshops before. Despite currently having 335,000 km on the odometer, an average fuel consumption of 3.7 liters per 100 km is possible on the highway at 90 km/h. In my daily commute, including traffic jams and cold starts, I achieve 4.2 liters per 100 km... so I can, including a reserve canister, drive 2,000 km to Austria to refuel. The vehicle is largely original.

- all filters etc. are original Audi parts.
- Shell 5W-40 oil - Oil changes with engine flush every 25,000 km, no measurable oil consumption.
- Shell Diesel, Wörgl (affordable and good quality).
- Oil change at ATU Innsbruck (because the service is friendlier).
- Continental summer tires, 2.9 bar (!!) all around.
- The MSW (Multi-Switch Module) was repaired and adjusted using VAG-COM.
- Integrated VAG-COM interface, USB version.
- AGR (Automatic Gearbox Restriction) reactivated after the test phase, as no noticeable benefit was observed.

In that regard, I wish you continued success with your AEL (Advanced Engineering Laboratory). If you need any logs or other reference materials, please don't hesitate to contact me.

Tuppie.

hello Tuppie,

Thanks for your reply!

Unfortunately, my collection currently only contains junk.
( more details can be found under Thread https://community.dieselschrauber.org/en/viewtopic.php?p=47195#47195 )

I'm starting to work on my car myself again, even though I barely have the time. The workshops were just too incompetent to get it right, and I was too lazy to keep hauling it back and forth (I've already spent over 6000 euros on parts there, not even including labor costs!).

"I can only dream of your fuel consumption! I'm currently getting 11-13 liters per 100 kilometers, and I'm driving relatively fast (160-180 km/h, mostly on the highway), but even so, those are terrible numbers for me. Before, I was getting 7-8 liters per 100 kilometers at 190-220 km/h. I can barely reach that speed now (and I also have a performance chip installed)."

Almost everything has been replaced now, but without success (including the second new fuel injector pump)!

I could use some reference logs for comparison purposes.

and specifically,

1.) Taktung Spritzbeginnventil Gruppe 004 ; der 4. Is it valuable?
This should be between 4-40% throttle, while mine is at 65-75% idle.

2.) Group 007; Value 3 represents the intake air temperature. Please record this value when the engine is cold to exclude any heat dissipation effects. I also need the outside temperature for comparison (possibly from the outside temperature display in the instrument cluster).

3.) group 000; the 8th value represents the intake air temperature. In my case, this value consistently deviates from the outside temperature by approximately 2 to +20 degrees (even when the engine is cold).

Values according to the Audi repair manual.
243 = -20 degrees.
236 = -10 degrees.
226 = 0 degrees.
211 = 0 degrees.
196 = +20 degrees.
177 = +30 degrees.
155 = +40 degrees.

At an outside temperature of approximately 15 degrees Celsius, I'm getting a value of 171 to 182 (in group 007, the value of 3 is correct).


and if it doesn't bother you, I would like to see a direct comparison of the log values 003+008+011 from a measurement run on a straight section of road (e.g., a highway).
1.) At idle for 20 seconds, then a short burst of acceleration to 3500-4000 RPM, followed by another 20 seconds at idle.
2.) In 4th gear, from approximately 1000 RPM to the maximum RPM plus 10 seconds.
3.) In 6th gear, from 1200 RPM to maximum RPM + 10 seconds.

It would really help me to compare my system to yours, since it seems like everything is working perfectly with you (in terms of performance and power consumption).

For example, in my case, there's already a difference in boost pressure at idle of almost 0.29 bar (Group 011, second and third values; the target value for me is 1275 mbar, but the actual value is 989 mbar)!
Is it the same for you too?


I hope I'm not asking too much, but it's very difficult to find someone who drives an AEL vehicle, doesn't have any problems with their car, and can also provide log data.

If it's too much to ask, that's also okay with me.

If I can ever help, I'd be happy to do so.

Best regards, Kristian.

Hello Kristian,

Basically, everything is possible once. Nothing will probably happen immediately, but I'll try to see what I can do , so first, what comes to mind.

- The target boost pressure is actually a myth. 1200 mbar at idle is incorrect. In fact, even on my daily commute at 90 km/h, I have an actual boost pressure of approximately 998 mbar, which is 50 mbar above idle. And this is while cruising at a constant speed.

- I have a large, partially documented collection of logs, and I'm sure something similar to what you're looking for is included. Just email me, and I'll zip up the entire package and send it back to you.

- Your high fuel consumption... unbelievable. Hard to imagine. Or is it? I also had fuel consumption readings of 8 liters initially at speeds of 150 km/h. It was impossible to drive that car with less than 5.5 liters per 100 km. Eventually, I discovered that the rear brakes were 80% locked. One of the rims was also always hot. In my home workshop, I found the cause: the brake calipers were completely corroded. The pistons were stuck on both sides, and even worse, the sliding bolts were severely corroded. I removed the pistons and rebuilt the calipers, installed new floating calipers (is that what they're called?), and now they've been running for 130,000 km without any problems. After that, the fuel consumption was about 1-2 liters lower.

You can drive 10km on the highway without using the brakes and then let the car coast to a stop at a rest area. Feel the rims/brake discs. In my car, I can touch the brake discs, and they are ice cold. In the past, the entire rim used to get hot.

Maintain a constant speed of 90 km/h according to the speedometer on a flat surface. What does the fuel consumption display show? Reset the MFA (Multi-Function Display) and maintain a constant speed of 1-5 km/h. Anything above 4.5 liters is not normal.

How about tire pressure? I've always had nitrogen in my tires, so I thought checking the pressure was unnecessary – that's what the ATU here in Munich told me. Turns out, that was wrong; the tire pressure kept dropping. You can imagine the impact on fuel consumption and tire wear. The solution: metal valve caps with a seal. Since then, the pressure has been fine. You can also see the difference immediately with a mountain bike, as the volume is even smaller.

Are the timing settings correct? What is the idle speed setting on your car? Is it 1000 or 1200 RPM? I've found that on my car, the injection timing seems to be set based on the 1000 RPM table, even though the idle speed is set to 1200 RPM. When I adjusted it based on the 1200 RPM table, the engine became harder to start.

Transmission fluid level okay? My ARX 6-speed was very low and almost empty. Recently, I added Liqui Moly transmission oil leak stopper and topped it up. Last time I checked in Innsbruck, I had a liter bottle of transmission oil with me, but it was unnecessary – I haven't lost any since then, over 25,000 km ago.

As described, optimal operation depends on x factors. Frankly, the AEL is good, but considering so much has already been replaced, it's almost more likely that the problem lies elsewhere. I mean, if you were nearby, I'd like to take a look, just based on my experience of knowing how a good one feels.

I'm going to take a nap now, so check in and let me know what's happening.

Good luck!

Tuppie.

Hello Tuppie,

Could you please also send me the logs? I'm seeing the exact same (incorrect) values as Kristian in the MWB 11: 1.275 mbar setpoint versus 989 mbar actual value in idle mode.

I'm also experiencing similar issues: it's smoking a lot, the maximum speed is around 190 km/h, but the fuel consumption is "only" 7.5 - 9 liters. However, I have a 30,000 km service coming up soon, and I want to investigate the problem more thoroughly after that. It might just be the diesel filter or the air filter, for example.


Okay, here's the translation:

Thank you.

Thomas.

PS: I've now ordered the full version of VAG-COM. I hope it will provide me with more useful data, such as TDI-Graph.

hello Tuppie,

Regarding boost pressure... in my father's car (AAT engine, 115 hp, original configuration), the boost pressure at idle is 1080-1150 mbar, and as soon as you ease off the accelerator, it surges forward noticeably. It's quite possible that you have very little boost at 90 km/h if you're in the "load-free" area of the engine's performance curve (as determined by the engine control unit). In that case, the ECU will automatically reduce the boost pressure, and you might even have less than atmospheric pressure if more air is being drawn in than the turbocharger can supply (the turbo acts as a flow restrictor, which is also noticeable when you go from full boost to idle immediately – in this case, you might even measure values below atmospheric pressure).

The issue with the rear brakes is a well-known problem for the Audi A6 C4 (and also the Audi 100 Type 44, as they have the same brake system).

I've experienced this issue before on my other Audi, and also on my dad's car. I check it more frequently and sometimes add more lubricant if it seems stiff.

I have a similar experience with tire pressure. I only drive with air. I'm currently at 2.75 bar all around, having reduced it from 3.3 bar. The ride comfort noticeably decreases starting at 2.8 bar. From a driving perspective, you only start to notice a difference when you go below 2.2 bar (with the standard tire size of 205/60/15H). Above 3.3 bar, the car becomes undrivable in fast corners, as it tends to push straight ahead instead of turning.

Because of the fuel consumption, I once tried to be "strict" for a week and only drove at 80-90 km/h (sorry, I was just "cruising"), but the result was more than 8 liters.

"Maintain a constant speed of 90 km/h according to the speedometer on a flat surface. What does the fuel consumption display show? Reset the MFA (Multi-Function Display) and maintain a constant speed of 1-5 km/h. Anything above 4.5 liters is not normal."

Okay, I'll do it later... crap, I don't have MFA enabled.

I always fill my tank until I see the visible mark inside the fuel nozzle.

"The valve timings are okay. The 1000/1200 RPM issue definitely depends on the engine control unit (ECU), including the software version installed. I've tried both versions here. Simply observe the engine speed while adjusting/checking the valve timings."

Of course it starts better with the 1000 setting because you shift your display range visibly downwards, which automatically puts you into the early ignition zone (provided the engine control unit has a 1200 RPM limit).

The transmission is also fine and almost dry. However, I recently had to replace the oil pan gasket because it was leaking.

I've only been experiencing water loss for about 4 days, but I can't see any obvious leak. I think I'll try using a UV indicator.

Best, Krissi.

@klopfer, kristian

I will make sure to clearly name and zip my collected logs in the next few days. If anyone needs them, please send me a private message with an email address.

'8 liters per 100km while idling! That's terrible. In any case, that definitely has nothing to do with the turbocharger; at that low power output, it's practically inactive. It must be something else. I hope your water loss isn't a sign of a blown head gasket...'

Tuppie.

hello,

There were exactly 8.8 liters during the "truck brake pad games" (<= they might have been upset!!!! or maybe they all knew me because of the horn!?!).

I probably discovered the "water devil" that steals water!

There is a significant amount of white residue visible on the clutch bell at the stub for the heating connection, located at the rear on the front side, below the pump drive belt. I suspect that the rubber ring inside the stub has been affected somehow, and that it is leaking from there.

Best regards,
krissi

hello,

Just wanted to give a quick update on how things are going.

I found the "water devil"! It was the rear water connection fitting that had broken off.

Well, one problem less, and now we're already dealing with the next one => CAT.

Everything else remains the same without any changes.



Best,
Krissi

Hello,

I've now also purchased a full version of VAG-COM and ran the TDI timing checker. In the basic settings mode, my AEL revs up to 1,200 RPM. With the 1,000 RPM setting, my values are exactly in line, and with the 1,200 RPM setting as well, but unfortunately, on the upper . It took me a while to notice that, but as they say, those who can read are clearly at an advantage...

I'm planning to have someone adjust the settings soon, as I'm not really comfortable doing it myself. I'll let you know how it looks afterward.

Regards,
Thomas.

Hello,

@ klopfer

Adjusting or correcting the ignition timing is actually quite simple, and besides, you now have the appropriate tool for it (VAG-Com).

If you loosen three 13mm hex screws on the injection pump and one 6mm Allen screw (inbus), you can adjust the injection timing to your desired setting by rotating the pump.

Engine temperature must be at least 85 degrees Celsius, and all consumers (lights, air conditioning, radio, etc.) must be turned off. After tightening the screws, double-check everything, and that should be it. If you don't have "two left hands," you can do this in about 10 minutes (15 minutes if you also need to remove and reinstall the engine cover).


If you have any further questions, please feel free to ask. (Perhaps we can send something via email to help with understanding.)

Best regards,
krissi

Hello Kristian,

Okay, I'll give it a try next week. I have vacation then, and I have to change the diesel and air filters anyway.

Report back.

Regards,
Thomas.

Good day, everyone!

A heartfelt THANK YOU to this NG! I just managed to get the correct valve timing for my engine using your instructions and help. Now my readings are close to the target values again, and even in the correct diagram .

@Kristian
Thank you very much, and of course also to you. The private message issue has been resolved.

Regards,
Thomas.