Data Collection for Standard Turbocharger Control.

Hi everyone,

Since the turbocharger pressure control system sometimes causes problems (mainly with VTG engines), I suggest that as many TDI drivers as possible who have a boost gauge post their experience values when the turbocharger is hopefully functioning normally.
This could then be used to create a data collection listing the "typical normal functions" for each engine.

In case of problems, one could then better assess the boost pressure curve of one's own car in relation to potential errors – provided that a boost pressure gauge is installed or a laptop/diagnostic tool is available for reading the data.

As a simple and reproducible comparison for data collection, for example, a full-throttle acceleration with a warm engine in 5th gear, starting from approximately 1200 rpm, should be performed on a relatively flat road. During this process, it can be observed at which engine speeds...

a) A pressure of 0.5 bar will be reached (as a "significant" pressure value for the boost pressure curve at low engine speeds).

b) The first intervention to adjust the pressure setting occurs: specifically, when the pressure suddenly stops increasing or even slightly decreases.

To determine the maximum pressure, you can accelerate from approximately 2000 to around 3500 rpm in 2nd or 3rd gear with full throttle and read the pressure in the range above 3000 rpm.

To differentiate or categorize, it should be specified, in my opinion, the engine type, year of manufacture, and the data obtained from a driving test.

I'll start here.
97 AFN.
0.5 bar is reached at approximately 1300 rpm.
1. Control intervention: at 1500 rpm with 0.9 bar.
Maximum pressure at full load (above 3000 rpm): approximately 1.05 bar.

(corrected on May 27th; the initial values were from memory)

Hello,

'Some time ago, I measured the turbo boost on my old Golf 3 TDI (66 kW) using a quality pressure gauge from VDO/Dresser.'
As far as I can remember, the results were as follows:
Up to approximately 1900 RPM, the boost pressure would briefly rise to just over 1.2 bar and then immediately be reduced to approximately 0.95 bar. This boost pressure then remained constant across all gears, starting from 1900 RPM, until the maximum speed of 195 on the speedometer (actual speed 188).

Can someone tell me/write to me where I can connect the pressure gauge on a Golf 4 TDI 66kw? I haven't found a connection similar to the one on a Golf 3 TDI.

Regards,

Eike.

Hi.

It's still available at this link:

http://www.diesel-schrauber.de/forum/messages/135.html

(With a little searching, you could have found this yourself, in the thread about the boost gauge in the Golf 4.)
And there's even a search function here .

Hello Ulf,
Thank you for the tip; it was helpful.

This time, I searched, but I couldn't find anything: Where is the pressure sensor located in the intake manifold (Golf 4, 90 hp)? Besides the mass airflow sensor, I haven't found any connectors on the pipes.

My idea: to tap into the signal and display the boost pressure using a moving-coil meter. It's probably cheaper than a boost pressure gauge. Is it an analog sensor, or a digital one?

Regards,

Eike.

Hi.

I vaguely remember that the sensor is located quite hidden near the LLK (Low-Level Control) outlet. It operates analogically and provides a voltage that increases with pressure between pin 1 (ground) and pin 3 or 4. One of these pins (the "wrong" one) should be the 5-volt power supply.

It is questionable whether the sensor can withstand the output load when connected to a moving-coil instrument. It might be safer to insert a buffer between them, such as an op-amp or a transistor emitter follower.

Hi Ulf,

Is the pressure sensor checked during engine start (boost pressure = 0)?
Idea: Place a diode in series with the output signal. If your assumption is correct (similar to pressure, the output voltage increases between 0 and 5 volts), then the charging pressure should be able to be increased by approximately 10%.

What do you think about that?

Regards,

Eike.

Hi.

The principle is sound, but I have some slight concerns regarding the lifting strength.
Starting from the 2.5 bar (absolute) sensor in my engine control unit, a decrease in the measured voltage of 0.6 volts would correspond to an increase in pressure of approximately 0.3 bar.

1.3 bar of boost pressure instead of 1 bar is quite a significant increase... especially when you consider that a simple increase in pressure doesn't necessarily result in more power.
So, what's the point of all this?

Hi Ulf,

This measure might be suitable for optimizing the 10-cent tuning process to minimize soot emissions.
A germanium or Schottky diode would likely be more suitable for this application. I'll try it out sometime and check the charging pressure with a pressure gauge.

Regards,

Eike.