Help: Shaking at 1.9TDI Passat, Year 1994

Hello everyone,

Maybe someone can help me (I hope so).
The car hesitates between 1200 and 2800 RPM like an old donkey.
Constant driving is not possible, but there is no problem when accelerating to full speed.
Engine control unit read out, no errors found.
Needle changer replaced (thankfully borrowed), no improvement.
Relay 109 has been newly installed, but there is no improvement.
Air mass sensor disconnected and driven in emergency mode, no improvement.
Injector start valve checked, no improvement.
Does anyone have any ideas what it might be?
It seems I have an error that no one else has.
For a few tips, I would be very grateful.

Greetings
Bully

Hello,

Have you also checked the AGR?

Hello,

Have you also checked the AGR?

Stupid question, but what is AGR??

AGR = Exhaust Gas Recirculation

Check out the section on 'Technical Articles / Functionality of Exhaust Gas Recirculation'
-> very well described

Yes, at the AGR, I have already replaced all the vacuum hoses.
and the safety valve was also removed.
According to the description in the article, it should be on the right side of the engine, between the LMM and the timing belt, in the direction of travel, or??
But I don't have any coughing or a decrease in performance.
Thank you, but already for the tip.

Hello Bully,

Have you already checked (or had checked) the spray pattern and the tightness of the fuel injectors? If everything else seems okay, there might be a problem with the fuel injection pump (the metering valve might be too loose or too tight).

Hello,

Fuel injectors are sealed.
I need to take a closer look at the fuel injection timing.
I really hope it's not something with the fuel pump. (That would be expensive.)
Hey guys, thanks so much for the super quick responses.

Hello Bully,

Apparently, the faulty pump should be able to be tested. When the sensor for the speed signal is disconnected, the car will run normally (CAUTION: the speedometer will not work). If the shaking stops, it is likely due to the pump (Bosch service statement).

Hello Bertil,

Where is the sensor for the speed signal?

...on the gearbox,
I can't tell you which of the two connectors you can't identify because I don't know the Passat mechanics. On the G3, when viewed from the front, the connector is located at the rear of the gearbox (the other connector is visible from the top right). One of the connectors is for reverse gear, and another is for the speed sensor. This should be testable.

By the way, if the throttle lever is released, the engine shut-off function is disabled, and the transition from idle to full power results in a very abrupt and violent jolt.

If the speed sensor is faulty, according to my recollection, there is an error message in the dashboard instrument. Take a look at the error memory.

Greetings, Rainer

PS: As a result of another issue, I had temporarily disconnected the speed sensor on my own vehicle. When accelerating from 1000-1500 min-1, the engine started to jump excessively, normal normal acceleration without the jumping could only be achieved with a great deal of skill.

I thank you.
I'm going to try it out tonight.
If this 'pulling out the plugs' continues, I'll soon have all the parts in the engine compartment gone.
I hope this will then clarify the error.
I'm probably going to have no more crowns soon, but my wife says that this helps against orange peel skin on my butt

Bully wrote:

Help with shaking at 1.9TDI Passat, year 1994 The car hesitates between 1200 and 2800 RPM like an old donkey. Constant driving is not possible, but there is no problem when accelerating to full speed. Engine control unit read out, no errors found. Needle changer replaced (thankfully borrowed), no improvement. Relay 109 has been newly installed, but there is no improvement. Air mass sensor disconnected and driven in emergency mode, no improvement. Injector start valve checked, no improvement.

Hmm, manufactured in 1994. . . the first TDI models had a potentiometer in the pump as the primary control element - which, of course, is considered a wear part in the medium or long term and can lead to jerking etc. at high mileage

Measure the resistance between pump cable 1 - 2 and 2 - 3: the (wear-free) HDK sender has approximately 6 Ohms in each case.
If you measure significantly different (higher? / I don't know the exact difference) values, that would strengthen my suspicion of a worn-out sensor.

Hello Rainer,

Also, ein Fehler in der Kombiinstrumentanzeige ist nur bei einem Instrument, das über den CAN-Bus kommuniziert, möglich. Und ich denke, dass der Passat aus dem Jahr 1994 noch nicht über diese Funktion verfügte (auch mein Golf 3 aus dem Jahr 1996 hatte es nicht). The error occurs here in the motor computer (this was the case for me).

Bertil wrote:

Hello Rainer, Also, ein Fehler in der Kombiinstrumentanzeige ist nur bei einem Instrument, das über den CAN-Bus kommuniziert, möglich. Und ich denke, dass der Passat aus dem Jahr 1994 noch nicht über diese Funktion verfügte (auch mein Golf 3 aus dem Jahr 1996 hatte es nicht). The error occurs here in the Motorcomuter (this was the case for me).

Hi Bertil,

ok, bei mir war ein 1998er A3. What surprised me back then was that there were no error codes displayed in the engine control unit. I tried back then
a) Restarting the cruise control (ultimately, the problem was the steering wheel switch)
b) to eliminate the erratic idle speed at speeds of 2-30 km/h (failed due to lack of gear recognition; otherwise, I would have simply stolen the speed signal from the engine control unit at speeds below 30 km/h and without a gear engaged).
Error was only stored in the combined instrument.

Hello, Rainer

Good morning,

If the fuel injector is worn out, does that mean a new fuel injector is needed?
I can also handle the jerking quite well, but then I can hardly give it any gas.
If the speed sensor is faulty, does it only result in one error entry? Or does the rattling then stop, and if it doesn't stop, is the fuel pump then defective?
I'm currently unable to fully follow you.

Best regards,
Bully