Throttle position error (G79) and boost pressure issues

Hello,

I'm new to this forum.

After searching for a long time in this forum, I unfortunately haven't found any solutions to my problems.

ich habe folgende Probleme an meinem Passat 35i Bj:1995 Motor 1Z 90Ps. Manual transmission.

For the past 4 days, I've had an idle speed (LL DRZ) of 1300 RPM, and it's showing a fault code 00777: 'Throttle position sensor (G79) - implausible signal.' I checked the throttle positioner based on the data from AutoData, but it seems to be working correctly. The resistance value is increasing steadily. The first switch ('SS') opens at approximately 6 degrees of throttle opening, and the second switch closes around 90 degrees of throttle opening. Therefore, it should actually be functioning properly.
'However, if I gently touch the accelerator pedal and the tester shows a value greater than 0% throttle position (approximately 0.5% to 2%), the low-speed idle speed drops back down to 900 RPM. If I release the accelerator pedal again, the low-speed idle speed returns to 1300 RPM.'
I've been thinking about simply adjusting the gas pedal sensor a bit to keep the LL DRZ at 900, but unfortunately, that doesn't solve the problem. In the diagnostic tool, under 'Measurement Values 2,' in the first three windows displayed from the front, the '0' doesn't change to a '1' when I accelerate. It should actually do that (at least, that's how it works on an A4 1.9 TDI).
Otherwise, the car runs great and has no issues like jerking or stalling; it's just the problem with the LL (likely referring to a specific component or system).

I'm afraid I don't know what to do next. Has anyone else encountered this problem before, and is there a solution?


'So, the second problem is that I changed the resistor for the boost pressure in the engine control unit from 10k ohms to 27k ohms (I did this a while ago and it's not related to the issue of the noise coming from above).'
'I checked the LD pressure before changing it with an external gauge; the value was 900 mbar with a boost of 1100 mbar. After switching to a 27k resistor, the value dropped to only 850 mbar and 1200 mbar boost. The resistance should have been correct (the middle pin of the pressure sensor). I'm currently using a 10k resistor again. I'm using injectors from the 110 HP engine, which unfortunately causes excessive black smoke.'
Why does the value tend to decrease rather than increase?



Since yesterday, it's also showing the error message: 'Load signal generator - implausible signal?'.


I hope someone can help me.

Best regards,

Okay, I just checked all the connectors and everything looks fine.

Furthermore, I checked the switches and potentiometer on the control unit connector, and all the values are correct. Therefore, the control unit is receiving the correct signals.

The strange thing is that I can't clear the error code; it only disappears when I press the accelerator pedal beyond 0%, and it also goes away when I use the DRZ (presumably a diagnostic tool).

That's all very strange.

After receiving so many responses, I tried a different control unit today, and lo and behold, the LL DRZ is now normal, and there are no more errors. Everything is back to being okay.

Unfortunately, I haven't found a solution to problem number 2 yet.
I then soldered a 27k ohm resistor into the new control unit, but the boost pressure did not change; I measured it directly on the hose leading to the control unit.

Best regards,