Performance drop at top speed after Abt chip tuning

Hello everyone!

I'm new here, but I still hope to do everything right, so I'm posting my problem here.
I drive an Audi A4, model year 1996, with a 1.9 TDI engine (110 horsepower) and an AFN engine code.

This weekend, I bought and installed a used engine control unit (with identical part numbers) that has an *** chip installed. Then, I had the immobilizer (VAG 1551) synchronized, and everything seemed to work perfectly at first! The increased power (now 132 hp) was noticeably felt during acceleration.

Then I got on the highway to test the top speed.
The suit was and is great overall, however, when I exceeded 200 km/h (with the tachometer reading over 4000 RPM), I suddenly experienced a loss of power!
But when I got back down below 200 km/h, everything was fine again!
And that's also the case now, so I'm going to limit my speed to 200 km/h for now.

Okay, here's the translation:

Now, my questions:
What is the cause of this decline in performance?
Is it possible that the engine control unit, or the chip inside it, is defective?
Could it be related to the turbocharger? By the way, it has already covered over 150,000 kilometers.
The engine is a replacement engine and still has a warranty.
I was given the advice that the gears inside the turbocharger's turbine are not supposed to be exposed in the high-pressure area. Could that be possible?
What is the cost of such a rod and its installation? How?
What other causes could there be?
The turbocharger can't be broken yet, right?
Because the full power is available in the suit, and it can reach speeds up to 200 [units - e.g., km/h, mph].

I'm feeling quite desperate because I don't know how to act and I'm worried about whether more things might break! Or should I perhaps reinstall the old control unit?
Unfortunately, I don't have that anymore. If I did, I would try it and see if the error occurs in that case as well. Actually, everything was fine with the control unit at the final speed.
I'm hoping to find someone who has experienced something similar before, or who is knowledgeable about this topic.

I haven't had the engine control unit read yet.
Does this cost money?

Thank you and best regards.
Carsten.

Hello,

Quote:

What is the cause of this decline in performance?

No idea, the crystal ball is broken right now.
What does the engine control unit's fault memory indicate when the problem occurs?

Quote:

Is it possible that the engine control unit, or the chip, is defective?

Anything is possible...

Quote:

The engine is a replacement engine and still has a warranty.

You should keep that in mind when doing engine tuning. In case of an emergency, it can get expensive.

Quote:

I was given a tip that the turbine in the turbocharger is not supposed to be operating in that high range. Can that be it?

Yes.

Quote:

What does such a frame and installation cost? How?

The pole is not sold separately. It would also be pointless to replace the lever that moves the stuck mechanism in the turbocharger.
It's like breaking your foot and then buying new shoes...

Quote:

The turbocharger can't be broken (yet), right?

No, but soon. What do you mean by "broken"? "Broken" can also refer to a situation where there is a 1-liter oil consumption due to a defective roller bearing or seal.

Quote:

I'm a bit desperate because I don't know how to act and whether more things can break!??

1.) If you don't read the error codes from the diagnostic system when the error has just occurred, you won't be able to do anything.
2.) Yes, things can eventually break down.
3.) You should start by reading this:

Okay, I'm ready. Please provide the German text you want me to translate.

Best regards, Rainer.

Okay, I just went to the Audi dealer and had the error codes read.
The following error occurred:
00553 028
Air Mass Meter - G70
Short circuit after positive voltage.
intermittent error
sporadic error
occasional error

Does that mean the mass airflow sensor is defective?
Could there be other causes for the error message?
Is it also possible that the shaft in the turbocharger can't handle the higher pressures caused by the chip, simply because it has never operated in that range before? Or is it possible to rule out such an error message?

Furthermore, I would like to know the difference between the Garrett turbochargers with part numbers 028 145 702 C and 028 145 702 H. I inquired and found that the turbocharger with the 'C' at the end is for my A4 model year, while the turbocharger with the 'H' at the end is for the A4 models from the year 1998 onwards. However, both turbochargers are for the same engine code, which is AFN. Could I also install a part with the designation 028 145 702 H in my car?

Thank you again for your answers.
and I hope to receive a more competent answer this time than before.

Regards,
Carsten.

Hello,

You've almost already given yourself the answer.
It could be a faulty mass airflow sensor or its wiring to the control unit.

Fix this error first, and for now, forget about the boost pressure control.
Tip: Try logging the measurement blocks along with the mass airflow readings.

Best regards, Rainer.

Hi,

and check the fuel supply. If the fuel pressure is incorrect, the injection timing will revert to an earlier setting.

The effect could be as follows: As the engine speed increases, the ESP (electric fuel pump) draws in more diesel. This increases the vacuum in the suction line. If this line is not completely airtight, or if the filter is already somewhat clogged, it could draw in air. This leads to pressure fluctuations/pressure drops in the ESP, which affects the injection timing, which is pressure-controlled.

Mine had the exact same thing.


I agree with Rainer that the error entries need to be corrected first. If necessary, temporarily replace the mass airflow sensor (MAF) using the diode method and see if it makes a difference.

I don't think it's a turbo, and I don't think it's a can or a rod.
If the turbocharger bearings were to suddenly seize up at full throttle, which corresponds to a power output of approximately 25 kW (!) in the turbo, it would be scrap metal just milliseconds later. If the rod is jammed, it would likely jam again when it's under full pressure. The resulting pressure spike would shut down the turbocharger via the MSG (Manifold Absolute Pressure sensor), at least until the next start.

I don't think it's the motor either, but if you already had an original MSG and an AT engine with a warranty, it wasn't smart to give that up. If the engine has any more issues and you have the tuned MSG (engine control unit) installed, you've essentially sold the MSG cheaply and can use the money to buy a new engine!

Let me read how the story continues.

Hello!

How should I log the measurement blocks along with the air mass measurement values?

And you, 'garth.brooks', did you also get the exact same error message when you encountered your problem?
And what exactly should I do to control the fuel supply?
And what exactly is the diode method, and how does it work?

If the engine ever has a problem, I'll find a replacement original control unit beforehand and only then will I go to the dealer.

Thank you and best regards.
Carsten.

Hello Carsten,

Relaxanz wrote:

Hello! How should I log the measurement blocks with air mass measurement values?

Okay, I will translate the text. Please provide the text you want me to translate.

Relaxanz wrote:

And you, "garth.brooks", did you also get the exact same error message when you encountered your problem? And what exactly should I do to control the fuel supply? And what exactly is the diode method, and how does it work?

I'm going to be bold and answer...
Error message: No, that would cause problems with the ESP injection start.
Fuel supply: see the link in my previous posts.
Diode method: Replacing a faulty Hot-Film Mass Flow Meter (HFM) or Laminar Mass Flow Meter (LMM) with a silicon diode (for testing purposes).
Okay, I'm ready. Please provide the German text you want me to translate.

Best regards, Rainer.

'The thing about the 'everything is OK' error message is true; it doesn't actually indicate anything is wrong, and the workshop will just send you home.'
'It says 'The chip probably turned off' !!! ??? '

As a former full-time software developer, I wondered how the MSG could have reprogrammed itself, and I never contacted those friends again.

Otherwise: Searching is rewarding, especially in this forum.


Okay, one more thing - I can't really imagine an MSG (Message System) defect either. It's possible, of course, but since it's mostly digital technology, it's more likely to be related to digital errors.

Okay, either it works or it doesn't. Usually, there's nothing in between.

I've also experienced the LMM error 2-3 times!

It appeared, and then it was gone!

Just observe!

P.S. My boost pressure sensor and mass airflow sensor have 225,000 km on them after being modified!

Regards,

Manuel.

Good tuners also reduce the power output slightly, even at peak RPM and high speeds, perhaps to the original level, so that the engine can handle full throttle for longer distances... which is what's expected of a TDI.

Hello everyone!

Regarding the previous comment:
I believe that *** is a reputable tuning company and that they considered features like that.
But even so, the performance at top speed shouldn't drop off that drastically.

And regarding the second-to-last comment:
I'm relieved to hear that someone has experience with this and is reporting positive results.

And to the others:
I bypassed the mass airflow sensor using the diode method this weekend.
And then the error was gone, and I could easily reach top speed.
Okay, I'll go ahead and buy a new mass airflow sensor, and then it should work again, right?

The forums and tips here are really very comprehensive and also very good.
However, accessing the data from my vehicle using a laptop seems a bit too complicated for me. It's not that I wouldn't be able to do it, but I simply don't have the time, and I'm not a mechanic or working in the automotive industry.
I think it's great that someone developed something like this and is now using it!
I would really need to delve deeply into those kinds of things, and that's something I'm not able to do right now.

I will post again as soon as I have the new LMM installed in the car and have tested it.

I must say, I'm very impressed with this internet domain; I wouldn't have thought it was possible to create something so well and comprehensively.

Regards,
Carsten.

Hello,

Thank you for the compliment!

Quote:

But, for example, accessing the data of my vehicle using a laptop seems a bit too extreme to me.

When it comes to the mass airflow sensor , the diode method can be a reliable way to detect a defect.
In many other cases, you simply have no other option than to check what's happening inside the corresponding control unit.

Best regards, Rainer.

Hi, I'm not going to just leave it like that with the issue of it being too complicated to use VAGCom for reading the data.

Here's what needs to be done:

Acquire an interface, if necessary, buy it on eBay and resell it later.
Get a laptop (someone has one).
Download VAGCom Shareware.
Find the OBD port in the car.
Infecting.
Let's get started.

If you consider that you're exchanging something that's perfectly fine for something else with a 50% chance of being broken, it's still a highly profitable investment.

Hello Garth,

I've already seen that there are cables like that available.
But there are several, one for OBD, one for OBD2, and also one for USB.
Is an OBD serial connection sufficient? Do I need an adapter for that?
What do I need for my Audi A4, model year 1996, TDI?
There's a socket in the center console, located in the ashtray for the rear passengers.

You're right, once you have the cable and the connection established.
It shouldn't be a problem anymore.

But why would they exchange something that isn't even broken?
Can I use this to prove something, or to determine what can be ruled out?

Thank you and best regards.
Carsten.

OBD serial communication is sufficient, provided that the available device still has an RS232 port.
The "noble" USB version is intended for the neutered, newer models of the "Schleppi" (likely a specific product name).

Quote:

But why would they exchange something with me that isn't even broken?

What do you think this forum exists for, thankfully?

Quote:

Can I use this to prove something, or to determine what can be ruled out?

Do you really have such strong reservations about looking at some professional articles? Reading educates...
The pressure relief valve of the modules is being stressed.
OlBe.

Hello,

Relaxanz wrote:

Hello Garth, I've already seen that there are cables like that available. But there are several, one for OBD, one for OBD2, and also one for USB.

OBD1 and OBD2 stand for On-Board Diagnostics version 1/2. USB = Universal Serial Bus.
USB is a bus system in a computer and has nothing to do with OBD initially. It's simply the physical connection for a diagnostic adapter. Besides USB versions, there are also adapters available for the PC's serial port.
Your A4 TDI, manufactured in 1996, does not support OBD2. However, you can still read all relevant control unit information using VAG-COM. The software offers at least the same range of functions as the original VAG diagnostic system, and in some cases, it even exceeds it.

Relaxanz wrote:

Is an OBD serial connection sufficient? Do I need an adapter for that?

Yes, if you have a serial port on your PC/laptop.

Relaxanz wrote:

What do I need for my Audi A4, model year 1996, TDI?

Current offers in the online shop, for hobby use, I recommend this one. Or, you could simply take a look at a diagnostic article.

Relaxanz wrote:

But why would they exchange something that isn't even broken?

Because they want to make money, or simply are unable (do you keep replacing parts until the error is gone)?

Relaxanz wrote:

Can I use this to prove something, or to determine what can be ruled out?

If you go through the technical articles on dieselschrauber.de, the answer is a clear YES.

Best regards, Rainer.