Dear all,

Last Thursday our Scout suddenly starting running rough and the engine produces something like a bopping sounds as if air is blown back the wrong direction. The noise goes with the revs if that makes sense. She's also down on power slightly and when removing the air intake cover and losing of the air intake with your hand the bopping noise goes away.

A local garage tested injectors (flow), compression (equal on all cylinders) and EGR valve, all seems fine. There are no lights on on the dash at all and there are no faults showing on a read out.

It nearly sounds as if she's of a cylinder but she's not apparently. The car is drive able but the noise has us concerned obviously.

Any ideas suggestions are welcome.

It's the pd engine.

Dear all,

Last Thursday our Scout suddenly starting running rough and the engine produces something like a bopping sounds as if air is blown back the wrong direction. The noise goes with the revs if that makes sense. She's also down on power slightly and when removing the air intake cover and losing of the air intake with your hand the bopping noise goes away.

A local garage tested injectors (flow), compression (equal on all cylinders) and EGR valve, all seems fine. There are no lights on on the dash at all and there are no faults showing on a read out.

It nearly sounds as if she's of a cylinder but she's not apparently. The car is drive able but the noise has us concerned obviously.

Any ideas suggestions are welcome.

It's the pd engine.

Ps. It looks like the noise is amplified by he air box if that makes sense

http://www.audi-sport.net/vb/audi-s4-a4-a4-cab-b7-chassis/147458-a4-2-0-tdi-2006-misfire-blow-back-noise-lack-power-help-please.html

Sounds very much like our problem...

Sounds like worn cam followers then.

What mileage has she done?

80k on clock but not original head for engine. Head was replaced after cam belt came off. We have no details for engine that head was taken from but seller told us mileage on that engine was "similar". Car was going like a clock when we bought her in January, used little or no oil, very economical, no smoke etc...this just happened from one day to another...seems common issue for pd engines...

Car is back. New camshaft and 8 tappets, oil change with filter and she's going like a lock...damage came to 700 Euro.