A6 2.5L TDI AKE - Performance issues, later turbo

Hello to all the assembled experts,
Unfortunately, I'm having two problems with my A6:
1.) Intermittently, there is no power when accelerating; it's completely gone. The automatic transmission downshifts, but there's no power. After a short time, it returns to normal. The problem mainly occurs in the summer. Even after the engine repair (see 2.), there is no change; the issue still persists. Images/logs:
/viewtopic.php?t=15749 under: 001_003_011_plot.jpg with the log file: /download.php?id=2145

"About 4 weeks ago, I had a major overhaul: new camshafts, fuel injectors, and a new turbocharger (installed by Motorenprofi Bielefeld). While it runs smoother now, I feel like it has less power, and the turbo seems to kick in relatively late (the turbo "boost" doesn't really start until around 2200 RPM). Based on the logs/plots, it seems like it's running rich, especially under full throttle. Is this normal?" The LD deviation from the target value might still be within the acceptable tolerance, or is it significantly too low?
Is there anything else you notice?
The image 008-009-011-passau.jpg (/viewtopic.php?t=15749) shows full throttle with MAF above the threshold ...
Log in: /download.php?id=2143

Thank you in advance for any tips, suggestions, or advice on how I should proceed.

Best regards.
Grumpftl.

Unfortunately, I can't open your log files; it seems like some kind of web filter is blocking them (I'll investigate further when I'm at home). I can't interpret the graphics.

Both the LD (lambda sensor) and the air mass sensor need to follow the target value; they shouldn't be running in a "limp home" mode. Mine isn't doing that, and I suspect there's a problem with the vacuum system. I'm going to investigate the air mass sensor, the vacuum lines, and the EGR valve. But, as I said, I haven't seen any logs yet.

Without log files, it's definitely difficult to interpret what's happening. But I can explain the diagrams based on the values.

008-009-011-passau.jpg:
Line 1: Engine speed (RPM), IQ driver (mg/Hub), IQ RPM (mg/Hub), IQ MAF (smoke).
Line 2: Engine RPM, IQ automatic transmission, IQ torque monitoring, IQ anti-slip system.
Line 3: Engine RPM, Intake manifold pressure (spec.), Actual intake manifold pressure, N75 valve duty cycle (%).

Okay: green: requirement, yellow: Russian border (that's how I interpret it).
rosa: target load, weiß: actual load.


001_003_011_plot.jpg
Line 1: RPM, Throttle position (%), Switches, Coolant.
Line 2: Engine RPM, MAF sensor specification, MAF sensor actual value, EGR duty cycle percentage.
Line 3: Engine RPM, Intake manifold pressure (spec.), Actual intake manifold pressure, N75 valve duty cycle (%).

Okay, so: light green for the gas position, turquoise/dark green for the MAF values.
pink/white: LD as above, should/is.

I hope that at least the plots are a bit clearer .

Best regards,
Grumpftl.

Am I the only one receiving this message?

It works for me (but I don't have WebWasher running). Perhaps it only recognizes .xls files as Excel files? I didn't choose that guy, though.

I'm not receiving the message from WebWasher.
It's probably an issue with you, your company, or the provider.

Best regards, Maxx.

Okay, you're right. I'm not getting any notifications at home either. However, I did take a look at your first file. As mentioned in this forum, your file isn't really usable (or I don't want to put in the effort to make it usable). I even converted it to a CSV file, which was a waste of time.

There's a CSV converter available for VCDS that makes the data more readable. Then you should do a full-load test, running the engine from approximately 1000 rpm to 4500 rpm, rather than constantly changing the throttle position with low-load conditions, etc.

I personally create a chart in Excel showing the desired and actual air mass, the desired and actual load, and a second chart showing the quantity limits. All charts use the engine speed as the horizontal axis. Then everyone can analyze the data.

What I could see is that the air mass in the LL (low load) is quite high. Did you disable your EGR (Exhaust Gas Recirculation)?

I would check if the VTG is fully engaged in your place. In my case, there was a vacuum leak. The 5 cm hose directly connected to the pump was porous. The symptoms I experienced were a delayed response, constant low-end boost, and all values across the RPM range were below the target values. It sounds similar to what you're experiencing. Ideally, proper logic would be desirable.

The two logs are in the format used by VAGScope for display (VAGCom also uses the .csv extension).
If it was processed through the converter (which is included with VAGCom), it can "only" read Excel files.
"And I had a bit of trouble getting the times right in Excel, because each individual work order (MWB) uses its own time. So, when I tried to combine all the values using the time from the first work order..." The current representation of MWB no longer reflects the correct relationship.

That's why I thought the VAGScope could do it better, so I'm leaving it as is to make it readable.
I'm re-attaching the two files after converting them.

"In the log ("...Passau"), there are a few points with engine speeds between 1000 and approximately 3500 rpm. This happens very quickly, and even with the Tiptronic, I can't really reach the rev limiter; it automatically shifts up (and in 3rd gear)." There's another "hidden" gear change included in the sequence.


The AGR (Abgasrückführung) is not deactivated (at least, not knowingly).
If there's a leak, blockage, or defect somewhere, wouldn't the control system constantly try to activate the EGR valve without anything actually happening?

"How can you further verify that the VTG (vehicle traction generator) is fully engaged?" It's unlikely you'll be able to do that while standing still, without any additional power requirements, right?
Or with an actuator diagnosis? Will the entire adjustment range be traversed?

So many questions, thank you very much for your effort.
Grumpftl.


P.S.: A friendly greeting to owners of 2.5L TDI vehicles: V (2. Camshaft


P.S.: Something else I noticed: In case 1) (no boost), no pressure builds up even with full throttle. In the log file, you can see that in these specific cases, the N75 valve remains at 15%. Isn't that abnormal already?

Here are the questions I can try to answer:

Grumpftl wrote:

1) The two logs are in the format used by VAGScope for display (VAGCom also uses the .csv extension). If it was processed through the converter (which is included with VAGCom), it can "only" read Excel files. "And with Excel, I had a bit of trouble getting the times to align correctly, because each individual work order (MWB) uses its own time. So, when I tried to combine all the values using the time from the first work order..." The current representation of MWB no longer reflects the correct relationship. 3) That's why I thought the VAGScope could do it better, so I'm leaving it as is for readability. I'm re-attaching the two files after converting them. 4) In the log ("...Passau"), there are a few points with engine speeds between 1000 and approximately 3500 rpm. This happens very quickly, and even with the Tiptronic, I can't really reach the rev limiter; it automatically shifts up (and in 3rd gear...). There's another "hidden" gear change included in the sequence. 5) The AGR (Aktivkohlefilter) is not deactivated (at least, not knowingly). If there's a leak, blockage, or defect somewhere, wouldn't the control system constantly try to activate the EGR valve without anything actually happening? 6) What other methods can be used to verify that the VTG (vehicle traction generator) is fully engaged? It's unlikely you'll be able to do that while standing still, without any additional power requirements, right? Or with an actuator diagnosis? Will the entire adjustment range be traversed?

1) I know. Take a look at my metrics.
Okay, I'm ready. Please provide the German text you want me to translate.
2) Please also refer to my values. A slight offset is insignificant and is also present in your data. Whenever you are recording multiple measurement devices simultaneously.
3) It can, but I don't like your casual flirting. See the technical article on how to manage and process log files.
4) However, I'm currently unable to get in again. But if I recall the accelerator pedal position (which was also included?), those brief increases in RPM weren't at full throttle. Could you please try the 4th gear? Maximize the torque across the entire RPM range and deliver full power throughout.
"I don't know how yours behaves (automatically). In mine, the AGR valve precisely adjusts the air mass target. In yours, it's significantly higher than it should be. That's why I thought your AGR valve might be blocked." "Mine delivers your values without EGR."
6) While the engine is idling, fully depress the accelerator pedal, remove and then reattach the vacuum hose, and the entire range of throttle positions will be activated. Actuator diagnostics are also supported.

That's all from my side; I'm unable to interpret your values.

Have you seen the converted files yet? They are at least readable in Excel.
The accelerator pedal position was only recorded in one log file ("001_003_011_plot.jpg" and the corresponding log file), but not in the other curve. The situation shown in the diagram ("..Passau") indicates that this occurred in the second case. Climbing a hill (a short burst because the gear change is quick), full throttle from 1400 to 3000 RPM, then shifting up to 4th gear.

Here's the translation:

"What I don't understand about the diagrams you linked is that you're always plotting the values against the speed – I haven't heard of that before; usually, they're plotted against time, even in the corresponding technical documentation." Does it have a specific reason?

"You're probably right about the driving. I need to try it again in 4th gear. In 3rd gear, the full-throttle sections are very short; it shifts up quickly. In 4th gear..." The traffic is likely to be very slow at the end, and it probably won't be until a suitable alternative route becomes available again.
But I'll try it again.
I'll check the AGR (Abgasrückführung) and turbocharger settings; I didn't have time for it yesterday.

And I need to recreate the diagram in Excel sometime - but that will take a while, as it's quite complicated .

Grumpftl wrote:

Have you seen the converted files yet? "What I don't understand about the diagrams you linked is that you're always plotting the values against the speed – I haven't heard of that before; usually, it's always plotted against time (even in the corresponding technical documentation)." Does it have a specific reason? 3) In the 4th. The traffic is likely to be very slow

at the end, and it probably won't be until a suitable alternative route becomes available again.

1) No, that weird message again. I'll check it again at home tonight.
"Tell me yourself, can't we diagnose the problem much better with these values? This way, you can see which RPM range the issues occur in." Otherwise, one always has to search for the problematic speed.
3) I always do this on a deserted stretch of country road. However, it has 6 gears and it runs in 4th gear. Only 160 .

Oh yeah, the WebWasher .

It's certainly well-organized, no question about it. Simply because it's not overloaded with so much data.
And for once, it's reading higher than usual, going against the expected trend.
Whether it makes more sense to use speed or time as the axis – hmm, I'm not sure about that.
The question is whether the problems are speed-dependent or not. Or rather, "dynamic," depending on the background, etc.
hmm...

Regarding the test drive, well, with the 5-speed automatic transmission, it's quite fast. Try it out when you have a clear path .

Hi, somehow your log is still being displayed as a block of text. When I process my CSV log data through my CSV converter, I get individual columns as output.

What I consider to be full load (the driver's desired output is always different at the same RPM), I've noticed that the LD (likely referring to "load demand" or a similar term) comes on quite late.

Despite everything, it's quite difficult to make a definitive statement, and I still don't like the log data. In your log data, I only see full load, without any gear changes. Also, from the engine's low-speed RPM up to over 3000 rpm (ideally higher, but the problem with mine is actually at the lower end).

I can't say that it's running at full speed in the obscured state. It takes a long time for the LD (likely referring to a laser diode parameter) to stabilize, and as long as the LD is too low, it's forced to operate in the obscured state. In my opinion, it's not a problem related to air masses, but rather to the LD (likely referring to a specific weather phenomenon or model).

Given that you have a new turbo, I suspect the issue might be related to vacuum (the variable geometry turbocharger (VTG) isn't fully engaging, or isn't staying engaged long enough or at a wide enough angle, possibly due to the pre-injection map).

If that's not it, then the only other things that come to mind are:
- Air in the supply line to the VP44.
- Blocked cat.
- Adjustable valve timing.
- Incorrectly adjusted VTG rod.

Also, please also take a look at the idle speed control and the fuel injection start.

Interestingly, the files with the "conv_*" prefix are readable by Excel on my system.
Otherwise, nothing has changed with the data; I'll have to create new ones. Let's see, it'll probably be Friday...

The blurring was a mistake on my part; I looked at the wrong data field (the 3rd instead of the correct 4th ).

I'm going to check the vacuum system as much as I can – it's so crammed in there, you can barely get anywhere.

"I definitely have things to do and check, thank you for the tips so far - I'll be sure to let you know if anything new comes up."

Best regards and many thanks,
Grumpftl.


P.S.: When you see how many TDIs are out there on the roads, the technology must be quite unreliable or very difficult to control – and it seems like there are no problems with it during the vehicle inspection.

During the vacuum test, you could take a look under the expansion tank; I had a leaky hose there. Then, check all the cables for any signs of abrasion.

You can also measure vacuum pressure; there's probably someone here who can evaluate the values.

For my device, replacing the 5cm hose under the container only provided a temporary solution. I've now replaced all the wiring, I just need to find the time to install everything.