hohe Drehzahl => hohe VTG Stellung, Fiat Stilo 1.9 JTDm | Posts 16+

Thank you for your input. I will test this in the next few days.

I've now replaced the pressure sensor on the charger again, and everything remains the same. The boost pressure is still too low at the top end.

Finally, I connected and recorded the readings from a pressure gauge after the VTG pressure transducer. Everything seems consistent so far. This indicates that the pressure sensor is being calibrated correctly.

Here are three videos about it, along with a log from the day before yesterday.

Do you have a way to measure valve timing?
The two camshafts are connected via spur gears, but apparently with a camshaft adjuster.
Normally, the pressure on the exhaust side of a VTG (Variable Turbine Geometry) turbocharger should be significantly lower than the pressure on the intake side. However, if the VTG is heavily boosted and the valve timing overlaps, exhaust gases can flow into the intake side, which in turn reduces the power available to the turbine and causes the VTG to remain heavily boosted.
Ideally, the valve timing should be checked using measuring instruments.
However, the larger intercooler, and the increased air mass it allows due to the better cooling of the intake air, may counteract this effect, even at the same boost pressure.

Thank you for the additional input.

I'll check the valve timing. I have the tools for that. It includes a locking pin for the camshaft and a locking mechanism for the crankshaft.

I will also check the so-called EMP (exhaust manifold pressure). That's a good idea. A blind plate for the AGR (exhaust gas recirculation) plus a pipe, hose, and pressure gauge should be sufficient.

Okay, and one more thing:
I had the VE (injection control unit) checked by a specialist for a friend who works in diesel engine development. The VE fits perfectly and is also identical to those in comparable vehicles.

Hello everyone,

Short update: I'm experiencing boost pressure issues again in the higher RPM range!

I haven't really done any major testing yet. But today, I checked the valve timing.
Result: The timing belt is misaligned by one or two teeth. Why, how, or why not - I have no idea. I replaced it myself last time. I can only imagine that when my acquaintance changed the clutch, he might have turned the crankshaft in the wrong direction. This would relieve the tension on the timing belt tensioner, and the belt would slip. I was always there, but I don't have any other explanation.

Anbei eine Logdatei vom 4. Okay.

Regards,
Christopher.

OK, thank you for the feedback!

I would like to express my gratitude for the professional assistance!

Now, next weekend, a larger air pump can definitely be installed .

Here's one more small addition:

I have a new car! Everything that was previously not so great about the engine performance is now completely gone.

- While stationary, I felt vibrations in the brake pedal, but they are now gone.
- No more vibrations in the steering wheel when the vehicle is stationary.
- The engine runs much more smoothly and quietly => simply a well-rounded engine performance.
- Engine: More powerful and less prone to explosions.
- The engine noise is very quiet, even at high speeds (greater than 220 km/h).
- Above 160 km/h, I experienced vibrations occurring approximately every 2-3 seconds (like a humming sound that went through the car) => completely gone.
- No more excessive shaking when parking.
- Much better performance after enabling [feature/setting].
- Exhaust fumes are barely noticeable anymore // previously, they were very strong.

Interestingly, it has hardly any effect on the exhaust gas temperature, which remains almost the same.

Absolutely crazy what all of this has caused... And it's insane how quickly you get used to a bad engine running.

Okay, a little late, but here's one last addition:

It turns out that the problem wasn't actually the valve timing. While the valve timing was also incorrect, the main issue is the exhaust system. Currently, everything points to a defective downpipe and the resulting back pressure. In the past, I removed the catalytic converter for testing, but that didn't make a difference. Now, I removed the downpipe (the catalytic converter is located after the downpipe) for testing => and suddenly, all the values are within the normal range.

There's a significant lack of air mass both at the bottom and top of the engine, and I haven't reached the target boost pressure. The problem was actually exacerbated by the larger turbocharger. But just take a look at the before/after logs.

So, if there's a lack of air mass, the target boost pressure isn't being reached, and the exhaust gas temperature (EGT) is unusually high, simply remove the exhaust system for testing.

Viele freundliche Grüße,
Chris.

Hello everyone,

I had almost forgotten about this thread, but I wanted to let you know that something new has developed regarding the matter.

Unfortunately, the statement in my previous post was incorrect. It wasn't the exhaust that was the problem, but the intercooler.

Last September, I revisited the issue. For testing purposes, I installed a pressure drop sensor *before* the intercooler and connected a pressure sensor.

The result was absolutely terrifying.
With the required 2.0 bar of boost pressure (relative), the pressure before the intercooler was an unbelievable 2.3 to 2.4 bar. It's a miracle the turbocharger survived, but it's understandable that the standard turbocharger failed quickly.
Since the measurement is taken in the intake manifold, the VTG (Variable Turbine Geometry) will naturally adjust itself until the desired air-fuel ratio is reached at the measurement point, regardless of the pressure loss caused by the intercooler.

While everyone always warns about these so-called "Twinpass" LED light panels, I wouldn't have expected such values. Therefore, if you want to be on the safe side, you should measure the light output before using an LED light panel.

Using the same setup, I then made a comparison between standard LLK and Twinpass LLK.

Twinpass LLK.
4425 RPM | 2716 mbar | 38.47% VTG

Series of liquid cooling systems.
4404 RPM | 2782 mbar | 32.93% VTG

Now, a Tube&Fin LLK from Turbozentrum has been installed.

Compare it to a setup with more LD.

Twinpass LLK.
4453 RPM | 2957 mbar | 46.27% VTG

Series of liquid cooling systems.
4512 RPM | 2970 mbar | 33.69% VTG

Tube and fin heat exchanger.
4570 RPM | 2978 mbar | 34.80% VTG

The vehicle has been running with the new low-temperature coolant (LLK) since the end of September and is barely recognizable. The response is better, the exhaust temperature is lower, and the acceleration is significantly improved.