Hey guys just had a straight through on my polo 1.4 tdi was told it makes a loud owling sound changing gear . But sadly it doesn't does anybody know why ?

One idea.

Would exhaust gas recirculation valve take some off the burnt diesel and air back to inlet when ease off the gas pedal to change gear

rather than blast down the straight through pipe?

Think he means the dump valve sound lol

Yeah but it's more of a pssssh on an atmospheric dump valve.

I think you need a broken EGR cooler to get a howl.

My mates waste gate makes and owl sound when it opens to the straight through exhaust

Thought they had Garrett VNT turbos - no wastegate.

Ten year old 1.9TDI certainly has.

Nope, looks to be a GT1544 cast into exhaust manifold with internal wastegate.

Edited 16 June, 201412 yr by dvderlm