Boost pressure too high 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 with a chip to approximately 210 horsepower.

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

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 was approximately +0.18 for all values.
At Block 14.
Cylinder 6 to 2 +0.25.
Cylinder 4 to 2 +0.28.
Zyl 5 to 2 - 0.16

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


I then took some more measurements of the mass airflow sensor, ranging from 780 to 1000.
Okay. Then I thought, 'Hey, why don't you check the boost pressure?'


now this is important, I've measured the setpoint versus actual pressure.
Here's what came out:

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

What do you think? Measurement error, or did the tuner exaggerate?

What I also find strange are the enormous pressure spikes of 1.5 bar, the extremely slow build-up of boost pressure, 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? Surely, 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.

Okay, then have a pleasant 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 overshoot itself is normal (in relation 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 force via the vacuum actuator is 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've seen was 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 that deals with overshooting. While doing that, I also logged an overshoot of 1.5 bar on a 90 HP ALH (without chip tuning --> the target value is 0.85 bar) ( /viewtopic.php?t=7902 ).

Considering that your engine is chip-tuned (and the target curve is already at 1.4 bar), I don't think these 1.5 bar are excessively high. However, I also find the target curve itself to be quite high. Okay, so if your turbo is supposed to consistently deliver 1.4 bar, then I would definitely start stocking up on a new one .
I would consider the curve labeled "as-is" with the 2.2 bar value to be the more accurate one. However, I also believe that your VTG (vertical travel gauge) might be the reason why it's not reaching the target value.
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 notice a decrease in performance.

That went by quickly. Thank you for your responses.

@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 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?

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

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' sound) when starting in first gear with full throttle, but it hasn't really done that for the past few days. Is it due to the low temperatures, I have no idea.


Here's another log file: 4. Let the engine idle up to the rev-limiter, then let it coast down to a stop, and then resume normal driving.

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 noticeably better in low outside temperatures compared to warmer weather. We've discussed this topic quite a bit here before, but without ever 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 charging pressure on your tuned engine is approximately 0.15 bar higher than the standard pressure. Around 4000 RPM, it's about 0.2 bar more.
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 checking the original part for vibrations; that will guarantee it's the right one.

Best regards,

'Then it's probably gone again. With the Quattro and its over 400 Nm of torque, and the low truck-like RPMs, it also vibrates due to tension, which is noticeable even in 3rd gear at 1600 RPM. However, with front-wheel drive, the tires tend to 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. At higher speeds, it stabilizes again.

However, there's a problem: I only experience the effect in 6th gear . In the fifth [section/area], very slight signs are detectable, while in the remaining passages, there is 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's probably as you said: a boost pressure increase of approximately 0.1 to 0.15 bar. I hope the turbo can handle it, although the AKE is supposedly already at its limit from the factory.




@SD16
Unfortunately, it's 250 km to the tuner. It's not a chip or a box, but rather 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 get the Quattro to spin its wheels yet, except for in snow, and not even in first gear or in any other .
No chance, thanks to the torque-sensing differential. In winter conditions, it's then called 'oversteer' without end, 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 Celsius 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 boost 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.