High Boost After Chip Tuning?

First of all, hello everyone in this forum.

I have only participated in this forum as a reader so far, and I've already read quite a few interesting things.
I would like to ask you a question.

I have an Audi A4 2.5 TDI AKE with 180 horsepower, which has been tuned to approximately 210 horsepower.

I'm experiencing the following problem: For the past 5 days, I've been experiencing strong vibrations (a rumbling or humming sound) when accelerating in 6th gear, specifically between 1400 and approximately 1800 RPM. I've read in a forum that it could be caused by a loose clamp on the exhaust, a tensioner for the timing belt, or one or more faulty engine sensors (ESDs).

I then performed the recommended measurement using VAGCOM, specifically measuring blocks 13 and 14, which relate to 'idle speed control.' The result in block 13 showed that all the values were approximately +0.18.
At Block 14.
Cylinder 6 to 2 +0.25.
Cylinder 4 to 2 +0.28.
Zyl 5 to 2 - 0.16

Is the value of cylinder 5 still okay, or does it indicate a defect in the ESD?


I then took some more measurements . Air mass meter readings were between 780 and 1000.
Okay, so I thought, 'Hey, why don't you check the boost pressure?'


now here it comes, I've measured the setpoint vs. actual pressure.
Here's what came out:

http://img116.exs.cx/img116/6028/image0012fq.gif

What do you think? Is it a measurement error, or did the tuner exaggerate?

What I also find strange are the enormous pressure spikes of 1.5 bar, the extremely slow pressure build-up, even though it's a V6 TDI (which needs engine speed to drive the turbo), and the fact that the boost pressure remains below the target value, which I find a bit too high.
What do you think? The boost pressure can't be good for the turbo.


I haven't yet checked the VTG struts for proper free movement. A faulty charge pressure control valve could be the cause of the overshoots.

Questions upon questions, I would definitely be very happy to receive one or more answers.

So, have a good Thursday evening.

Hi,

Quote:

I haven't yet checked the VTG rods for free movement.

You should definitely do that. That's exactly what it looks like to me.

The overspeed value itself is normal (relative to the rest of the curve - my ASV also goes up to 2300, but mine is set to 2000), but if you look at the actual curve, you can see that it increases and decreases in steps, meaning it only adjusts when enough vacuum pressure has been built up to overcome the jerky VTG.

Best regards,

Jan.

Hello.

I find it hard to believe that it has 210 horsepower, because the power output of these V6 TDI engines is limited by the fuel injection pump. The highest power increase I know of is 18 horsepower.
The vibrations could also be caused by the tuning chip, especially if the torque has been increased too much!
Who tuned it?

Best regards,

Hi!
A few days ago, I also posted a topic about overboost. In that case, I logged an overboost of 1.5 bar on a 90 HP ALH (without chip tuning --> the target value is 0.85 bar) https://community.dieselschrauber.org/en/viewtopic.php?t=7902.

Given that, I don't think these 1.5 bar are excessively high for your engine with a chip tune (the target curve is also around 1.4 bar). However, the target curve itself seems quite high. So, if your turbo is supposed to consistently deliver 1.4 bar, I would definitely consider having a spare one on hand .
I would probably consider the actual pressure curve at 2.2 bar to be the correct value. However, I also think that the problem might be related to your VTG (Variable Turbine Geometry), which is preventing it from reaching the target pressure.
However, I don't think that has anything to do with the humming or vibration.

The ESDs look good to me as well. As far as I know, the tolerance is +2/-2 per cylinder .

Do you notice any loss of power? Or any other unusual behavior within the specified RPM range? If you've ever achieved the target boost pressure, and now the engine is being filled with approximately 0.2 bar less air than before, you should actually be noticing a decrease in performance.

That was fast. Thank you very much for your answers.

@SD16
'The chip is from TCM Tuning, a small company based in Bavaria. I've also read that if the driveshaft isn't perfectly balanced, it can cause vibrations after the chip is installed. I had it done last spring and haven't experienced any problems yet. However, the car isn't driven at full speed on the highway. Could it be that the low temperatures in recent days, which mean more oxygen in the air (MAF = up to 1000), have increased the torque and thus exceeded a certain threshold, triggering the vibrations?'

210 horsepower is quite common; most tuners offer that. Whether it's ***, Digitec, MTM, or others...

Does anyone know what the typical maximum boost pressure is for an AKE engine?

@wbuchi82
I read the thread . I wouldn't have thought so either. No, the car otherwise runs normally, with a fuel consumption of around 8 liters. I can't feel any loss of power. The only thing I've noticed in the last few days is that it used to make a slight rattling noise (like the Scheinwerferlicht Hintermann) when starting in first gear with full throttle, but actually not at all for the past few days. Could it be due to the low temperatures ? I have no idea .


Here's another log file: In 4th gear, accelerate from idle to the maximum RPM, then let the vehicle coast down and continue driving normally.

http://img65.exs.cx/img65/5553/image0023ri.gif

GRace wrote:

Could it be that the lower temperatures in recent days = more oxygen in the air have increased the torque (MAF = up to 1000) and thus exceeded the threshold to trigger the vibrations?

The 1.9 liter TDI engines I'm familiar with exhibit exactly this effect. They perform significantly better in low outside temperatures compared to warmer weather. We've discussed this issue quite a bit here before, but without pinpointing the exact cause.

Similarly, the 1.9-liter engines with increased torque tend to vibrate around 2,000 RPM, which is more noticeable in the winter but not present in the summer.

Since you received your chip in the spring, you haven't experienced temperatures below freezing yet. I suspect that's the explanation.

Best regards,
Uwe

Hi!


90 HP ALH (without chip tuning --> Standard value is 0.85 bar)

Just a small correction: The ALH has a target charging pressure of 0.95 bar.



Does anyone know what the typical maximum boost pressure is for an AKE engine?


The boost pressure on your chipped engine is approximately 0.15 bar higher than the standard pressure. Around 4000 RPM, it's about 0.2 bar higher.
I don't think these relative values are *that* bad.
However, I'm afraid I can't tell you how long the turbo will last.


Best regards,
Joe.

Try the original one because of the vibrations; it's 100% certain.

Best regards,

'Then it will probably disappear again. With the Quattro, which has over 400 Nm of torque and the low engine speeds typical of trucks, it also vibrates due to stress, which is noticeable even in 3rd gear at 1600 rpm. However, with front-wheel drive, the tires will likely slip.'

Hello everyone, thank you very much for your suggestions and answers.

@Uwe
Okay, as I've heard before. Apparently, on the Quattro, the issue is with the driveshaft connected to the rear axle. When the torque is too high, it starts to vibrate, and this vibration builds up until it becomes clearly audible inside the car. However, at higher speeds, it tends to stabilize again.

However, there's a counterargument: I only experience the effect in 6th gear . In 5th gear, there are very slight signs that can be felt, but in all the other gears, there's absolutely nothing.



@joe*
I looked at VAGCOM again, and it says that the boost pressure, in 3rd gear at full load, should be between 1900 and 2300. So, it will probably be as you wrote: an increase in boost pressure of about 0.1 - 0.15 bar. I hope the turbo can handle it, although the AKE is already supposed to be close to its limit from the factory.




@SD16
Unfortunately, it's 250 km to the tuner. It's not a chip or a box, but it was modified via OBD, so it's not as simple to revert to the original settings quickly, unfortunately.




@roli752001
I haven't managed to make the Quattro spin yet, except on snow, neither in first gear nor in any other .
no chance, thanks to the torque-sensing differential. In winter, this means endless acceleration, but only until the next turn, because the lateral forces unfortunately remain the same }.




I'm going to wait until it gets a little warmer outside (we're at -4 degrees and have had fog for 5 days here in the south) and then I'll check the VTG adjustment and observe the whole thing.

Is there a way to slightly reduce the turbo's boost to decrease the turbo pressure and torque in the lower RPM range, in order to check if the problem is related to the driveshaft?

Okay, see you later, thanks to you all.