Hi guys. 

 

So I´ve recently bought myself a really nice car, it´s a 2008 Octavia Combi with a 140BHP 2.0 Tdi PD engine code BMM. So far so good. 

The problem is when I start my car and the engine gets all warmed up it starts acting weird.

 

The symptoms are as described: 

 

If I hold still and accelerate with approximately gas pedal halfway down, a sound which sounds like a cyclical roar/growl sounding in sync with the revs.

 

E.g:

 

1st gear: Nothing from 900-1400 revs then "roar...roar...roar" until 2200 revs when I shift gear. The sound becomes more frequent as the revs goes up.

2nd gear: From, say 1200 revs until 1400 its ok, but then at 1400 the roar/growl returns... "roar/growl" and the engine coughs and power faints for a splitsecond simoultaneusly with the sound, it´s like the fuel injection is cut off and put on again and again... this goes on until 1600 revs. Then nothing up until 1800 where it does the same cycle as just described until 2200 revs. Shift gear.

3rd gear: shifting in at 1500 revs, and sound is more discrete now. 

 

It has a "swushing" sound when the thrust is cut off. 

 

I apologize for my bad english but hope you can understand my description. The symptoms are only present when the car is put under load during driving, when im parked it just acts normal. 

 

I have changed the fuel pump and the fuel filter which was all black from motoroil. So thoose money werent wasted but my symptoms are still present. 

 

Do any of you have any suggestions for where to start? I am suspecting the EGR, the N75 valve or maybe the turbo or even a leak in the air/vacuum system but frankly I am quite confused about what to do here. 

Hope you can help me! 

Best regards John

 

Might be worth seeing if you can get a recording and post it up.

 

Have you checked all of the boost hoses are OK - no leaks or chance of a collapsing under load. Does it do it if you rev it without being in gear and under load ?

 

You can quite often find a boost leak by looking for blow-by (oil misting) at the boost hose connections, I had a BKD A3 similar engine but not identical and had issues with the flat o-rings that they use in the hose connections.

 

Any fault codes logged ?

Might be worth seeing if you can get a recording and post it up.

 

Have you checked all of the boost hoses are OK - no leaks or chance of a collapsing under load. Does it do it if you rev it without being in gear and under load ?

 

You can quite often find a boost leak by looking for blow-by (oil misting) at the boost hose connections, I had a BKD A3 similar engine but not identical and had issues with the flat o-rings that they use in the hose connections.

 

Any fault codes logged ?

I´ll try to record something, but difficult since the symptoms are only present when driving. It doesnt do it when i am not in gear. E.g. when i am standing still with the engine opened and im standing besides listening.

Havent really checked more than looking from above with a flashlight. Nothing to see, Where your issues as mine? 

Havent logged any fault codes, but my mechanic maybe should have logged while driving a little round and provoking the issue to come...