2.0 TDI 140 issue - Limp Mode, Black Smoke

[Davidjay85]

Hi Guys,

 

Just joined the forum, I have a slight issue with my car and hoping to get a bit of advice on what to do next.

I have a 2005 Audi A4 S-Line 2.0 TDI 140 which I have owned since August last year. The car drove brilliantly at that point.

The Problem

A couple of months ago, the car started to hesitate slightly on acceleration before the boost kicked in followed by black smoke coming out of the exhaust when it did pull away.

The problem has been getting worse and the car has now gone into limp mode (I think). EML on the dash and its not boosting, not revving past 3k rpm although it will boost at random sometimes and go back to normal for about 10 seconds. Then back to limp mode. I'm avoiding driving at the moment as I don't want to make it worse.

Diagnosis

I had the codes read and had:

P0234 - Turbo Overboost condition

P0101 - Mass air flow performance problem

P0404 - EGR valve performance problem

Following this I decided to remove the EGR Valve and throttle body and clean them up, refitting them with new gaskets. I also cleared the codes and EML and took it for a drive. Same problem still in Limp Mode.One thing I did notice is when the EGR valve was off the car is that the flap does not appear to be fully closed. Is this normal? I have a photo I can upload of this.

Can anyone advise on what to do next before I take it to a garage?

Is it worth changing the MAF? Could the turbo be at fault? Should I replace the EGR valve with a new one? Could it be something else all together that causing this issue?

One thing thats in the back of mind is that several months ago I accidentally put a bit of petrol in. No more than £10 worth of Petrol, then filled it up with lots of diesel afterwards £60 or so. I have been told that this could not cause the issues i'm having but I'm not so sure...

Any advice will be very much appreciated. I cant really afford to give it to a garage as I know it will cost me a bomb and I'm convinced it is probably something simple.

Thanks for reading,

David

[Davidjay85]

This is my EGR valve. Does anyone know if its normally slightly open like this? Or is mine broken?

[Liamhardy147]

Hey Davidjay85, sounds very similar to what I have just experienced this week in my motor. Exact same spec as yours mine being just the SE version.

How did you get on with this ?

 

[Petrol head]

On 4/15/2018 at 6:46 PM, Davidjay85 said:

Hi Guys,

 

Just joined the forum, I have a slight issue with my car and hoping to get a bit of advice on what to do next.

I have a 2005 Audi A4 S-Line 2.0 TDI 140 which I have owned since August last year. The car drove brilliantly at that point.

The Problem

A couple of months ago, the car started to hesitate slightly on acceleration before the boost kicked in followed by black smoke coming out of the exhaust when it did pull away.

The problem has been getting worse and the car has now gone into limp mode (I think). EML on the dash and its not boosting, not revving past 3k rpm although it will boost at random sometimes and go back to normal for about 10 seconds. Then back to limp mode. I'm avoiding driving at the moment as I don't want to make it worse.

Diagnosis

I had the codes read and had:

P0234 - Turbo Overboost condition

P0101 - Mass air flow performance problem

P0404 - EGR valve performance problem

Following this I decided to remove the EGR Valve and throttle body and clean them up, refitting them with new gaskets. I also cleared the codes and EML and took it for a drive. Same problem still in Limp Mode.One thing I did notice is when the EGR valve was off the car is that the flap does not appear to be fully closed. Is this normal? I have a photo I can upload of this.

Can anyone advise on what to do next before I take it to a garage?

Is it worth changing the MAF? Could the turbo be at fault? Should I replace the EGR valve with a new one? Could it be something else all together that causing this issue?

One thing thats in the back of mind is that several months ago I accidentally put a bit of petrol in. No more than £10 worth of Petrol, then filled it up with lots of diesel afterwards £60 or so. I have been told that this could not cause the issues i'm having but I'm not so sure...

Any advice will be very much appreciated. I cant really afford to give it to a garage as I know it will cost me a bomb and I'm convinced it is probably something simple.

Thanks for reading,

David

Hello David,

Have your concern fixed ?

One of my friend got the same symptoms in his car.

Thanks for your update,

Jose

[Finnish Q7]

Hi guys, before suspecting/changing the turbocharger or EGV valve, buy a good EGV cleaning agent and spray it into the air intake towards the throttle body with the engine at around 2500rpm.Buy an original MAF sensor and fit it to the air passage way. Buy Red Line diesel octane booster and pour the whole bottle into your fuel tank(at least half tank full) . Take your car for a 100km test drive,that includes full throttle.Drive your car like you have stolen it on the test drive. If you still have any fault codes after your test drive, clear them. Take the key out of the ignition and restart the engine after 2 min. This process will clear any carbon build up in the injectors, glow plugs, combustion chambers and throttle passage. The Red Line diesel booster additive will also lubricate and clean your feed pump and lubricate and clean your piston rings. You will regain full power after these procedures. 

Edited January 11, 2022 by Finnish Q7
Correction

[Stevey Y]

On 4/15/2018 at 2:32 PM, Davidjay85 said:

This is my EGR valve. Does anyone know if its normally slightly open like this? Or is mine broken?

Hi, no it should not be open at all I think the control box has gone and no amount of cleaning will cure it, the over boost is caused by to much EGR gas entering the system and gumming the turbine vanes.