Problems after conversion to vnt17 loader

Hello, I've been searching through the archive for quite some time now, but unfortunately without success...
I installed a VNT 17 charger in my AFN last week. Simultaneously, I disabled the AGR (Air Injection System). After the first test drive, the vehicle went directly into the 3rd gear and then into limp mode. The error message was 'Saugrohrdruck - Regelabweichung' (Intake Manifold Pressure - Regulation Difference). This occurred sporadically.
I have checked the VVT actuator linkage, and it moves smoothly. The turbo has 15,000 km on it and there is no play. When the ignition is switched off, the fault disappears. However, when I demand full throttle in 3rd or 4th gear, the problem reappears...

What might not work? I have all the necessary tools available.
informationen zum fahrzeug: 1996 audi a4 mit 1.9 tdi afn 4g. automatik, 214000km

Thank you very much.

Hi,

Log your boost pressure and the control signal for your vacuum valve for your VTG, then we'll be smarter...

Hello,

Please provide a log with the load pressure profile. Conduct a valve stem diagnosis and check if the VTG (Valve Train Group) is moving smoothly. Does the vehicle run normally until it enters the limp mode, or does the turbo boost feel stronger/more powerful than usual?

Regarding the error: Does the rule limit fall BELOW or ABOVE the limit?

Hypothesis: The VTG bar needs to be adjusted in length.

EDIT: DocSnydor was faster...

Greetings
Private

Hi,

Then look for 'Turbocharger Boost Control Difference'. Furthermore, check the target and actual boost pressure via a larger RPM range using the VAG-COM. It is very likely that the linkage between the loading arm and the container is incorrectly adjusted.

Just completed a test run with 1551, load pressure at 3000 RPM full throttle 2432 mbar
and have a 2nd error: mass airflow sensor short circuit after +..
@private area I can't say whether the turbo boost is stronger or weaker because it appeared directly after the turbocharger conversion. However, the boost is enormous up to the limp home mode. (It would be nice if it stayed like this...)
Knee joint diagnosis is complete and in order...

I just took a test drive with the 1551, load pressure at 3000 rpm full throttle 2432 mbar
That's approximately 1.4 bar of overpressure. Please refer to the technical articles for the exact specified values. The fact is, that it is already too much for the AFN in its standard configuration (without a chip).

Please adjust the VTG bar so that it generates less pressure.

EDIT: I just checked here /viewtopic.php?t=2992 . When there is too much bite or even problems with stalling at full load, extend the lever longer


and I have a 2nd error: mass airflow sensor short to ground..
Is it intermittent / can it be deleted? What are the LMM values like? Plausible? --> Comparison with target values, if necessary. Check wiring.

When the boost pressure is significantly too high, of course, a much larger amount of air is drawn in, which causes the output voltage of the MAF sensor to be higher than expected. Does the control unit interpret this as a short circuit to positive? I don't know, but first, I need to get my finances in order.

Greetings
Private

The LMM is functioning correctly, and the wiring appears to be in good condition. I will now proceed with adjusting the VTG control system and will report back once that is complete.
Thank you in advance.

I just adjusted the VTG lever, and it's now at 2240 mbar. The 'LMM' error is gone, but the 'Saugrohrdruck, regeldifferenz' error is still present... but it's no longer entering the emergency mode... Unfortunately, the performance has also decreased... I'll take a look, maybe the optimal setting hasn't been found yet...

Without load pressure adjustment in the chip, a VNT17 simply makes no sense.
Okay, so increase the pressure in the control field, and there won't be any emergency shutdown.
So, find a tuner who can adapt your chip to your manifold and also knows how to hold a wrench correctly.
"Off-the-shelf tuning chips are not a good option in your case, because you could have just left the old turbocharger in. Logically, all tuning chips are based on standard, unmodified engine hardware.

I don't understand why you installed the VNT17 in the first place, especially without a properly adapted chip, and what the purpose of that is...

Hello, Rainer

Rainer K. wrote:

I don't understand why you installed the VNT17 in the first place, without an appropriate chip, and what the purpose of that is...

I was just about to ask...

Rainer K. wrote:

I don't understand why you installed the VNT17 in the first place without an appropriate chip, and what the purpose of that is...

Hi Rainer,

Thomas had once installed a 17-inch wheel in his AFN-style golf car, as far as I know.

While the engine had already been modified, it was likely done without a specific tuning for the 17 model. As far as I remember, he didn't have any problems with the 17 instead of the 15.

However, if the engine remains in its original condition, the 17-inch wheels generally don't make sense (unless you want to install additional boost pressure reserves for later tuning).

Since I replaced my G70 (short circuit to ground), I no longer have the 'air intake pressure regulation difference' error!

Although my boost pressure of 1.3 bar at approximately 4,000 RPM is still within the acceptable range, despite the chip.

Performance-wise, it's easily a 1.5-second advantage in a straight-line acceleration test to have the 17 instead of the 15!

Please adjust my chip when the large nozzles arrive!

Greetings

Manuel

Quote:

Since I replaced my G70 (short circuit to ground), I no longer have the "air intake pressure regulation difference" error!

What is a G70?

Could it also be that it's just an illusion, that it improves because of that?
Denn eigentlich bekommt er doch desegen auch nicht mehr Sprit laut kennfeld !

ps.
I also have the big turbo lying around in my garage and I'll install it when it gets a little warmer. Then also a 12mm piston in the ESP, and a custom chip . You can certainly dream, maybe I can also implement that.

@caravanatic: Regarding the excessive loading pressure! Perhaps the lower pressure system isn't sufficient to fully load the VTG dose! Anything is possible...

Manuel Thomas wrote:

Since I replaced my G70 (short circuit to ground), I no longer have the "suction pipe pressure regulation difference" error!

Hi Manuel,

*click* that makes sense somewhere.

If the LMM (Load Monitoring Module) and the boost pressure signal are no longer compatible, the engine may enter limp mode.

I know a case where the hose from the pressure sensor (in the engine control unit) detached on the AFN.
From a boost pressure of 0.5 bar, the emergency shutdown reliably activated - apparently because the air mass increased without a corresponding pressure being measured.

It might have been the other way around with you...

What is a G70?

G70 = LMM


Could it also be that it's just an illusion, that it improves because of that?
Denn eigentlich bekommt er doch desegen auch nicht mehr Sprit laut kennfeld !

It's a measurable delusion for me, but I also have a tuning setting in the control unit.


@caravanatic: Regarding the excessive loading pressure! Perhaps the lower pressure system isn't sufficient to fully load the VTG dose! Anything is possible...

Then the boost pressure would be too low if the vacuum pressure cannot achieve the maximum position of the VTG valve. Increasing the loading pressure!

@ ULF,
I hope this remains the case for now. Although I have only driven 240 km, I have always been careful to ensure that the engine does not enter emergency mode, for example, by accelerating hard uphill.

Greetings

Manuel

Quote:

Then the charging pressure would be too low, if the vacuum pressure cannot achieve the maximum VTG adjustment. Increasing the load-bearing capacity!

Oops, I made a mistake. Good, now I know!