Turbocharger: Powerful Performance and More!

Hi,

Another peculiarity about my tractor:

The turbo is boosting pressure, even though it shouldn't be.

2000 RPM, Electric current = 0, Target pressure: 1030 mbar, Actual: up to 1152 mbar, N75 valve at 94.1% open -- 120 mbar too high.

Idle speed: 958 vs 1040 -- 80 mbar too high.

I'll measure the pressure readings while the system is stationary later; that should help me identify a potentially faulty laser displacement sensor.

Under load, it is perfectly regulated!

(EDITH: Based on the fact that the system is working under load, I conclude that the hoses are reasonably tight. Furthermore, there should be no boost pressure in idle. Therefore, a leak in the control line that closes the wastegate would not be noticeable.)

Are there any other meaningful explanations?

Okay, regarding the idle issue, my first thought would be to measure the atmospheric pressure; it might be slightly elevated during this time of year.

The increased pressure at 2000 RPM is explained by the principle of the wastegate: it opens when it is activated with >=0.6 bar. The N75 valve can only mix the pressure arriving at the wastegate with atmospheric pressure, thereby regulating it _down_. The wastegate then opens later (e.g., at 0.9 bar ).

However, the wastegate may not open below 0.6 bar of boost pressure, which means the engine control unit (ECU) may not be able to regulate the actual pressure down to the desired pressure.

Basically, the MSG can only start regulating the pressure at approximately 0.6 bar (for the wastegate). How well or poorly the actual pressure is controlled below that depends solely on how well the target pressure is programmed .

Regards,
Guste.

Ouch.

Sure, I realized I had overlooked that all the values labeled "setpoint" (which are clearly unequal) are below 0.6 bar.

Given that everything works as expected and there are no extreme outliers, everything should fit together nicely.

I somehow had the impression that he used to be "better" at it.

Thank you (sometimes you're just blind).
m;