Intake Manifold Pressure: Regulation & Mass Air Flow?

Hello!

I own an Audi 80 convertible with a 1.9L TDI engine, manufactured in 2000, and it has been chip-tuned to produce 115 horsepower. It only has 46,000 km on the odometer!
Problem: All driving situations are fine, except when driving at high speeds in 5th gear, approximately above 100-130 km/h, the emergency mode is activated.

I've read everything in your forum that relates to this topic, but I still haven't been able to find the error.

The valve timing gear is easily rotatable (tested with a syringe), but it's contaminated with oil, which shouldn't affect its function.
Edit by dieselmartin:
He's referring to the wastegate, because it's an AHU engine.

The VTG solenoid valve is likely opening, as a small amount of oil leakage was observed after a test drive without the hose attached.
Edit by dieselmartin:
The magnetic valve is correct because the TDI wastegate has a pressure relief magnetic valve and not a vacuum-pressure converter like the EGR and the VTG.


LMM cleaned, and I think the data is also okay.

Now, I'd like to perform a test drive for you using VAG-COM. Perhaps this will help me understand the issue and assist you better?!

But what exactly should I record, and in which driving situations? Also, what else could I potentially try?!

Thank you in advance!

Hmmm..... Apparently not enough reading has been done!

For example, it would be interesting to see the error code (MKB). Then, we should look at the specific error that occurred.
Please provide meaningful and visually clear representations, preferably as diagrams, of the individual measurement blocks 3, 8, and 11 under full load acceleration (1500 RPM - 4000 RPM in the third wave) and as close as possible to the point where the emergency mode is triggered.

audi80_cabrio_TDI wrote:

With chip tuning to 115 hp. . . Problem: All driving situations are fine, except for fast driving in 5th gear, approximately from 100-130 km/h, which triggers the limp mode.

There have been cases where the tuner increased the load curve (LD map), but not the limp home threshold .

If the usual few-second threshold for triggering emergency mode is only reached in 5th gear because the lower gears "end too quickly," the symptoms might superficially seem consistent (but of course, that doesn't necessarily mean it's the cause).

... I'm curious to see what the logs reveal.

Hello,

I've created the following logs, but unfortunately, for time reasons, they are currently only in text format. Sorry! But hopefully, this will be enough to help me.
The error doesn't always occur at the location described in the second log; sometimes it happens earlier, and sometimes later.


028 906 021 GC, 1.9L R4 EDC, 00SG, 1408.


Beschleunigung aus dem Stand, bis ca. 4500 U/min / 3. Sure, here is the translation of the text from German to English:

'Gang:'

'Gang:'

This word can have several meanings in English, depending on the context. It could refer to a group of people who are involved in criminal activity, or it could refer to a passageway or hallway.

Group A:, '003',,,, Group B:, '008',,,, Group C:, '011'
'Engine speed, MAF (specified), MAF (actual), EGR duty cycle', 'Engine speed, Injector quantity, Injector quantity, Injector quantity', 'Engine speed, Specified manifold absolute pressure, Actual manifold absolute pressure, Duty cycle'.
TIME,861-945,240-340,240-340,4-84,TIME,,?,?,?,TIME,,,,Boost Valve
MARKER, STAMP, /min, mg/R, mg/R, %, STAMP, /min, mg/R, mg/R, mg/R, STAMP, /min, mbar, mbar, %.
,0.66,861,260.0,448.9,59.8,1.34,861,0.0,28.0,26.2,0.00,861,958.8,1020.0,91.6
2.70, 987, 290.0, 478.8, 59.8, 3.35, 987, 17.0, 28.6, 25.0, 2.03, 861, 958.8, 1020.0, 91.6
4.64, 1953, 850.0, 558.6, 4.8, 5.28, 2919, 31.8, 35.2, 37.0, 4.00, 1239, 1407.6, 1030.2, 42.6
6.58, 1680, 255.0, 525.4, 27.9, 7.23, 1785, 30.2, 34.4, 26.4, 5.92, 2268, 1050.6, 1193.4, 62.6
8.54,2037,250.0,694.9,4.8,9.20,1155,0.0,29.4,29.0,7.90,2100,1887.0,1152.6,35.1
10.52, 1428, 850.0, 538.6, 4.8, 11.19, 1533, 45.0, 32.0, 27.2, 9.84, 1323, 979.2, 1040.4, 79.7
12.50,1806,850.0,734.8,4.8,13.16,1995,43.4,35.4,37.6,11.86,1659,1856.4,1111.8,34.7
14.44, 2310, 850.0, 847.9, 4.8, 15.08, 2499, 41.8, 35.2, 38.0, 13.80, 2163, 1887.0, 1326.0, 35.1
16.38, 2793, 850.0, 847.9, 4.8, 17.03, 2940, 40.6, 35.2, 37.0, 15.73, 2646, 1866.6, 1458.6, 34.7
18.33, 3213, 850.0, 847.9, 4.8, 18.98, 3360, 39.6, 34.8, 36.6, 17.68, 3087, 1866.6, 1489.2, 34.7
20.33, 3591, 850.0, 847.9, 4.8, 21.02, 3717, 39.0, 34.2, 36.8, 19.66, 3486, 1866.6, 1499.4, 34.7
22.30,3927,850.0,847.9,4.8,22.94,4032,38.4,34.4,36.4,21.66,3822,1856.4,1499.4,34.7
24.22, 4221.85, 0.0, 847.9, 4.8, 24.87, 4326, 38.0, 30.6, 35.4, 23.58, 4137, 1846.2, 1499.4, 34.7
26.17, 4452, 850.0, 837.9, 4.8, 26.82, 4515, 37.6, 25.4, 33.0, 25.52, 4389, 1785.0, 1458.6, 34.7
12/28/YYYY, 4620.85, 788.0, 4.8, 28.77, 4200, 0.0, 32.0, 30.4, 27.47, 4578, 1734.0, 1417.8, 34.7
'30.11,1638,250.0,555.3,4.8,30.76,924,0.0,28.4,25.8,29.43,2688,1111.8,1162.8,54.6'
32.04,861,255.0,435.6,59.8,32.67,861,0.0,28.0,24.4,31.40,840,989.4,1030.2,66.5
33.97,861,255.0,435.6,59.8,34.62,861,0.0,28.0,25.0,33.31,861,979.2,1020.0,74.1


And now, directly to the emergency mode, which was activated at approximately 140 km/h:

Group A:, '003',,,, Group B:, '008',,,, Group C:, '011'
'Engine speed, MAF (specified), MAF (actual), EGR duty cycle', 'Engine speed, Injector quantity, Injector quantity, Injector quantity', 'Engine speed, Specified manifold absolute pressure, Actual manifold absolute pressure, Duty cycle'.
TIME,861-945,240-340,240-340,4-84,TIME,,?,?,?,TIME,,,,Boost Valve
MARKER, STAMP, /min, mg/R, mg/R, %, STAMP, /min, mg/R, mg/R, mg/R, STAMP, /min, mbar, mbar, %.
1.30,1911,355.0,578.6,59.8,0.00,1848,4.6,35.2,24.6,0.64,1869,1264.8,1060.8,65.3
3.22, 2394, 635.0, 847.9, 59.8, 1.94, 2016, 14.8, 35.4, 28.6, 2.58, 2163, 1642.2, 1132.2, 34.7
5.19, 1722.85, 850.0, 631.8, 19.9, 3.89, 2667, 19.2, 35.2, 37.6, 4.53, 1785, 1030.2, 1132.2, 57.4
7.14, 2184, 850.0, 847.9, 4.8, 5.84, 1869, 40.0, 35.2, 34.0, 6.49, 2016, 1917.6, 1254.6, 35.1
9.09,2667.85,50.0,847.9,4.8,7.79,2352,41.2,35.2,38.0,8.43,2520,1887.0,1397.4,34.7
07/11/1974, 850.0, 741.5, 4.8, 9.74, 2835, 36.8, 35.2, 37.2, 10.40, 2226, 1071.0, 1203.6, 64.9
13.01,2205,850.0,847.9,4.8,11.72,2058,40.4,35.2,37.8,12.35,2121,1917.6,1305.6,34.7
14.97, 2415, 850.0, 847.9, 4.8, 13.66, 2268, 39.8, 35.2, 38.2, 14.32, 2352, 1907.4, 1377.0, 34.7
16.89, 2604, 850.0, 847.9, 4.8, 15.62, 2478, 39.4, 35.2, 38.0, 16.25, 2541, 1897.2, 1417.8, 34.7
18.83, 2793, 645.0, 847.9, 19.9, 17.53, 2667, 39.2, 35.2, 37.6, 18.19, 2730, 1897.2, 1438.2, 34.7
20.82, 2268, 850.0, 847.9, 4.8, 19.50, 2100, 0.0, 35.2, 32.4, 20.18, 2373, 1907.4, 1071.0, 34.7
22.79, 2394, 850.0, 847.9, 4.8, 21.48, 2310, 42.2, 35.2, 38.0, 22.14, 2352, 1917.6, 1387.2, 34.7
24.73, 2520, 850.0, 847.9, 4.8, 23.44, 2436, 42.0, 35.2, 38.0, 24.07, 2478, 1907.4, 1407.6, 34.7
26.67, 2625, 850.0, 847.9, 4.8, 25.37, 2562, 41.6, 35.2, 37.8, 26.03, 2583, 1907.4, 1417.8, 34.7
28.61, 2730, 850.0, 847.9, 4.8, 27.31, 2667, 41.2, 35.2, 37.6, 27.95, 2688, 1907.4, 1417.8, 34.7
30.59, 2814, 850.0, 847.9, 4.8, 29.28, 2751, 41.0, 35.2, 37.4, 29.96, 2793, 1907.4, 1428.0, 34.7
32.54, 2919, 850.0, 847.9, 4.8, 31.24, 2856, 40.8, 35.2, 37.2, 31.89, 2877, 1907.4, 1417.8, 34.7
34.49, 3003, 850.0, 847.9, 4.8, 33.20, 2940, 40.6, 35.2, 37.0, 33.85, 2982, 1907.4, 1417.8, 34.7
36.41, 3045, 850.0, 808.0, 4.8, 35.14, 3024, 40.2, 35.2, 37.0, 35.77, 3045, 1907.4, 1417.8, 34.7
38.38, 3066, 850.0, 801.3, 4.8, 37.06, 3066, 40.2, 35.2, 36.2, 37.70, 3066, 1907.4, 1264.8, 68.1
40.37, 3066, 850.0, 818.0, 4.8, 39.06, 3066, 40.2, 35.2, 35.8, 39.72, 3066, 1907.4, 1254.6, 68.1
42.31, 3066, 850.0, 811.3, 4.8, 41.02, 3066, 40.2, 35.2, 36.0, 41.66, 3066, 1897.2, 1254.6, 68.1
44.27, 3066, 850.0, 804.7, 4.8, 42.97, 3066, 40.2, 35.2, 36.0, 43.62, 3066, 1897.2, 1254.6, 68.1
46.21, 3066, 550.0, 808.0, 4.8, 44.93, 3066, 40.2, 35.2, 35.8, 45.57, 3066, 1897.2, 1254.6, 68.1
48.18, 2919, 255.0, 561.9, 4.8, 46.86, 3024, 0.0, 35.2, 28.6, 47.51, 2982, 1122.0, 1111.8, 68.1
50.15, 27.72, 250.0, 565.3, 4.8, 48.85, 2877, 0.0, 35.2, 26.6, 49.50, 2814, 1111.8, 1091.4, 68.1
52.12, 2646, 250.0, 565.3, 4.8, 50.82, 2730, 0.0, 35.2, 26.8, 51.46, 2688, 1101.6, 1081.2, 68.1
54.04, 2541, 250.0, 561.9, 4.8, 52.75, 2604, 0.0, 35.2, 26.6, 53.39, 2583, 1091.4, 1081.2, 68.1

audi80_cabrio_TDI wrote:

I have now created the following logs, but unfortunately, for time-related reasons, they are currently only in text format... sorry! But maybe it will be enough to help me.

"Yes, it will definitely be enough. But if you, as the vehicle owner and someone seeking help, aren't willing or able to invest the time to make it visually appealing, why should any of us want to? We are all happy to help, but we also have other things to do besides taking work away from strangers."

I'm sorry for the harsh words, but I can't do this anymore.

Regards,
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It can also be used as a verb, meaning "to gust."

hey,

'Sorry, that definitely wasn't what was meant.'
Sure, I'll make the time; I've already invested quite a bit, much to my girlfriend's annoyance *g*.
She's currently unavailable, but I thought you might be able to see something right away. Otherwise, I will definitely provide it later!

See you later...

Exactly as I expected!
'I completely agree with what guste wrote! So, I've created a fresh and lively Excel chart with Mwb 3 showing the target and actual values as separate curves in a single diagram, and I'll do the same for Mwb 11. The sheer number of figures is enough to give you eye strain.'

And then there's still a lot of information missing, such as the ICD code and the specific error message that was reported.
So, please try a little bit.

edit: I almost want to say that the error is 'intake manifold pressure below limit' or something like that?

So, the license plate number is AHU 332 874 .

The exact error code is: 00575 017 Intake manifold pressure control differential.
intermittent error
occasional error
sporadic error

The diagram is coming soon, but I've never created something like that with this type of data before... sorry.

Quick note:
In the convertible models, only the 1Z and AHU engines were available (which are largely identical), and these engines do not have a variable turbine geometry (VTG) turbocharger but instead use a wastegate turbocharger.

audi80_cabrio_TDI wrote:

The diagram is coming soon, as I have never created something like that with this type of data before. Sorry.

A diagram isn't absolutely necessary for now.
If necessary, you can also add a few "calculation columns" to the Excel log (but please without date formatting; use log values instead!), and you can use the formula assistant if needed.

1. Soot reduction minus torque limitation.
2. Boost pressure: Is below the target value.
Air mass: Is below the target value.
(preferably on the right-hand side of each group of measured values).

The problem can be analyzed quite well by examining the trend of these values.

Example: see my post from August 31st at /viewtopic.php?p=70204 (red column).

small contribution:
In the convertible models, only the 1Z and AHU engines were available (which are largely identical), and these engines do not have a VTG turbocharger but instead use a wastegate turbocharger.

Absolutely correct!

And if I'm reading the numbers correctly in the second log entry, it seems like the boost pressure isn't really building up properly...

"Solenoid valve" and "VTG" already made me raise my eyebrows yesterday. But with the engine number, it's clear: The AHU doesn't have a VTG.

Therefore:
Sure, here is the translation of the text from German to English:

**Title:** Initial text with edits and title changed to avoid too many errors.

**Text:** The initial text has been edited and the title has been changed to avoid having too many errors in this document.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hello, thank you again to dieselmartin for the edits! I probably didn't fully understand the difference between a VTG and a wastegate turbocharger .

I've now put all the measurement data into a nicely formatted Excel table for you all.
You will also find the calculated difference values below each table.

Perhaps you can see a little more now .

http://www.cybernetics.de/ben/upload/Messwerte_fertig.xls

[Translating...]

404

If you look at the target and actual Ld values in section 11 of the Mwb manual, what do you observe? Also, compare the target and actual air mass values in section Mwb3. What do you notice then?

In my opinion, shouldn't the hobel (a type of machine) contribute quite a bit of soot to the environment?

That thing doesn't have to be perfect.

If the boost pressure is actually high enough, meaning the air mass is correct, then it runs normally.

Until the engine control unit detects the excessively low boost pressure and initiates a limp-home mode.

With a mechanical boost pressure gauge, you can quickly determine if the turbocharger is actually producing the correct amount of boost and whether the problem lies in inaccurate measurements.

Bitte gib mir den deutschen Text, den du übersetzt haben möchtest.

If the boost pressure is correct and the mass airflow sensor (MAF) is reporting a higher value than it should, then the vehicle would really be emitting a lot of black smoke.