TDI 170 Engine Noise

[Alistair101]

Hi all,

VW Golf 2.0 TDI 170, '07 plate.

I have got used to the sound of the diesel after a year but from time to time, usually on light throttle I feel an ever so slight hesitation of the engine followed by the diesel sound sounding much much louder. It is particularly noticeable between 1500 and 2500rpm. I have tried to narrow down when this happens, usually after some constant speed driving, doesn't matter whether it is 30 or 50 or 70mph. When I press the throttle to accelerate I get this tiny pause when the noise starts. Usually a blast of power up to 3000rpm cures the noise and the engine sounds returns to normal.

I asked the dealer at the last service and they mentioned EGR operation could suddenly feel like a misfire so that part makes sense. What I have read indicates that EGR operates under light throttle loads up stops under harder acceleration. No one mentions the engine sounding louder during EGR operation. Does this make sense?

Thanks in advance.

[dir06]

I have the exact same problem on my 57 reg GT Sport, its already had one EGR valve replacement under warranty now the same symptoms have come back, so ive decided to wait until the first service is due before i book it in to get it replaced under warranty

[Alistair101]

Did the 1st replacement of the EGR valve fix the problem?

I will call my dealer today.

Thanks

Alistair

[Alistair101]

Ok, the problem is sorted out, or rather what I experience isn't a problem, it is a 'feature'.

The TDI 170 in my '07 Golf GT has a diesel particulate filter (DPF). The DPF sits right by the turbo on one side, the cat is the other side. Basically it filters out the diesel particulate into a special chamber. Once the chamber is approx 45% full and the engine is hot and under light throttle load, a 'DPF burnoff cycle' is activated. From what I understand fuel is added and the particulate matter is burnt off in the exhaust pipe. As this occurs, the engine runs rough, runs much louder, consumes more fuel and uses a little oil. I was told this is completely normal and has nothing to do with the EGR valve.

The master tech at my dealer told me that some customer of this engine who do alot of short runs actually get a warning light on on the dash indicating that the DPF chamber is full because the engine never runs long enough or hot enough to burn off the matter. Never saw this on mine but I do 2 or 3 long journeys each week.

Also, at the TDI 170 was one of the first engines to have the DPF added, at that time the TDI 140 engine didn't have one, though apparently the new common rail TDI 140 released in the Tiguan thing has a DPF as well so I guess queries to VW dealers along the lines of what I experienced are going to be come more regular.

Hope this is useful.

[dir06]

It solved the problem but after another 4 thousend miles or so then the dreaded droning noise came back after you closed the throttle as well as the louder sounding engine noise between 1000 and 2000 rpm,