[1.2 TDI Lupo] Car switches to limp mode every once in a while.

[bullturbo]

The car  strated going in limp mode every once in a while . I would shut it off and restart and it would be ok.The problem got worse  as i  was driving one day ,and now it only starts hard but shuts off as soon as i try to accelerate .I took of the fuel return line from filter and it looks like it gets fuel. Sorry i do not speak german .I do not know a lot about this cars but i love them 

 

[Lupo_3L]

The most important thing: What is saved in the fault codes. Without this, there would be too many possibilities.

But I consider the problem to be the VTG adjustment of the turbocharger and the fault code will be: Boost pressure exceeded.

But it also could be a clogged fuel filter, amongst many other reasons.

Bearbeitet 25. Januar 2022 von Lupo_3L

[bullturbo]

18 minutes ago, Lupo_3L said:

The most important thing: What is saved in the fault codes. Without this, there would be too many possibilities.

But I consider the problem to be the VTG adjustment of the turbocharger and the fault code will be: Boost pressure exceeded.

But it also could be a clogged fuel filter, amongst many other reasons.

I just replaced air filter ,same thing .What can cause the VTG problem?What is a good VAG scanner? 

[bullturbo]

Just now, bullturbo said:

I just replaced air filter ,same thing .What can cause the VTG problem?What is a good VAG scanner? 

 

Just now, bullturbo said:

I just replaced air filter ,same thing .What can cause the VTG problem?What is a good VAG scanner? 

Sorry ,i meant to say fuel filter 

[Nagah]

Moderator:

Please use proper subject for requests.

I changed subject for you.

 

- Nagah

[Phoenix A2]

If fuel supply to the engine is OK,

then next thing to check would be intake air.

 

Is intakte air filter is OK?

 

Another idea:

Does the so called shut-off flap return to idle position after engine shutoff?

This flap is controlled via a pneumatic valve in order to shut air supply to the engine only while engine turns to to achieve a softer engine stop.

Maybe the pneumativ valve is faulty and stuck in active position whiche causes the shut-off flap to close.

 

Another idea:

You mention initial engine start is "hard".

Does that mean it takes a long(er) time for the starter until the engine runs (more than 1-2 seconds)?

It could be that the gaskets of the "pump nozzle injector"s are worn which causes are air getting into the fuel pipe system.

 

vor 5 Stunden schrieb bullturbo:

What is a good VAG scanner?

 

Recommended, but also expensive diagnostic tool to be used with computer: VCDS from Rosstech

Cheaper but fully functional diagnostic tool to be used with smartphone: OBD Eleven

 

[DerWeißeA2]

Sorry, I was completely on the wrong track, so I've removed my answers here.

[bullturbo]

19 hours ago, Nagah said:

Moderator:

Please use proper subject for requests.

I changed subject for you.

 

- Nagah

Sorry

[bullturbo]

On 1/25/2022 at 5:25 PM, bullturbo said:

I just replaced air filter ,same thing .What can cause the VTG problem?What is a good VAG scanner? 

 

 I had a guy scan the car and this what i got 

17964 -Charge Pressure Control

P1556 35-10 Negative Deviation-Intermittent

 

18072 -Control Unit for PD Injectors 

p1664 -35-10 Electrical Malfunction- Intermittent

 

17552 -Mass Air Flow Sensor

p1144 35-10 - Open or Short to Ground - Intermittent

 

He also scaned the transmission: 00263 -Transmission  27-10 Implausible Signal-Intermittent

00297 Gearbox Speed Sensor(G38) 03-10 No Signal -Intermittent

 

 

And thank you to everyone who replied

 

 

[Phoenix A2]

All read fault codes are marked "Intermittent".

Have you tried to clear all fault codes, try to start the engine and read the fault codes again?

 

From the listed fault codes, for my understanding this one is most probably related to hard engine start and also engine turns off:

vor 7 Stunden schrieb bullturbo:

18072 -Control Unit for PD Injectors 

p1664 -35-10 Electrical Malfunction- Intermittent

 

This fault code may be caused by a broken cable loom that connects the injector valve with the ECU (engine control unit).

That is the first thing i would look after.

It is not the fault code 18074 which is usually caused by single injector issues.

Therefore i assume that the common line to the injector valves could be broken. The cable for it is brown/green and runs between injectors pin 2 and ECU pin 114.

 

vor 7 Stunden schrieb bullturbo:

17964 -Charge Pressure Control

P1556 35-10 Negative Deviation-Intermittent

Check that VNT mechanism is not stuck and that the vacuum for control is supplied without leakage in one of the pipes (it is maybe a good idea to exchange the vacuum pipes anyway as they are not expensive).

 

For the other fault codes: check first if they come back after clear of fault codes.

 

[bullturbo]

6 hours ago, Phoenix A2 said:

All read fault codes are marked "Intermittent".

Have you tried to clear all fault codes, try to start the engine and read the fault codes again?

 

From the listed fault codes, for my understanding this one is most probably related to hard engine start and also engine turns off:

 

This fault code may be caused by a broken cable loom that connects the injector valve with the ECU (engine control unit).

That is the first thing i would look after.

It is not the fault code 18074 which is usually caused by single injector issues.

Therefore i assume that the common line to the injector valves could be broken. The cable for it is brown/green and runs between injectors pin 2 and ECU pin 114.

 

Check that VNT mechanism is not stuck and that the vacuum for control is supplied without leakage in one of the pipes (it is maybe a good idea to exchange the vacuum pipes anyway as they are not expensive).

 

For the other fault codes: check first if they come back after clear of fault codes.

Thanks again. After clearing codes  and car starts for a few seconds then it shuts off . No new fault  codes  ,but maybe the engine does not stay runnung long enough. VNT is not stuck. I had a guy checking the car ,and he disconnected  plugs ,hoses  etc. I am thinking that maybe he tried to start and forgot to connect some and codes were stored.   Could the problem be from the Transmission code fault  ,Gearbox Speed Sensor?

6 hours ago, Phoenix A2 said:

 

 

[Phoenix A2]

vor einer Stunde schrieb bullturbo:

Thanks again. After clearing codes  and car starts for a few seconds then it shuts off . No new fault  codes  ,but maybe the engine does not stay runnung long enough. VNT is not stuck. I had a guy checking the car ,and he disconnected  plugs ,hoses  etc. I am thinking that maybe he tried to start and forgot to connect some and codes were stored.   Could the problem be from the Transmission code fault  ,Gearbox Speed Sensor?

 

Hmm, can you take a audio recording of how the engine sounds like?

 

It is to check whether the engine is shut down intentionally by the ECU.

Or whether the engine shuts down unintentionally because it is running out of fuel or out of air.

 

Have you checked that the shut-off flap is open and stays open after the engine has been started (flap is located in the same casing as the EGR valave)?

 

[bullturbo]

 

Am 27.1.2022 um 08:44 schrieb Phoenix A2:

 

Hmm, can you take a audio recording of how the engine sounds like?

 

It is to check whether the engine is shut down intentionally by the ECU.

Or whether the engine shuts down unintentionally because it is running out of fuel or out of air.

 

Have you checked that the shut-off flap is open and stays open after the engine has been started (flap is located in the same casing as the EGR valave)?

 

I do not know how to insert video ,but it is not shut down by the flapper ,it sounds like it runs out of fuel  .Max file i can attach is 2.93 MB ,any other way to attach video