As in title any idea what this could be. It's a slight dip in the revs when I press the accelerator and a psst noise. Drives fine just annoying. Oh and by the way hi again not been in here for a while! Alex.

Sorry should have been put in Skoda I area

The psst noise is air rushing into the inlet manifold through the gaps you're creating as you open the throttle valve, isn't it? Revs shouldn't really dip though, have you seen any warning lights on the dash? Do you have anything to read error codes with?

No warning lights so far nothing to read codes either though. It's ok just a bit annoying if it is s know issue I could guide the garage rather than them potentially taking me round the housed. Perhaps it is more of a hesitation for the revs to pick up.

On ours  (05 AZQ eng.) there was a slight hesitation/rev dip at 'launch' when the EGR valve was playing up (sticking open sometimes). I guess the ECU was having trouble making sense of its sensor readings as it was getting 'false air' from the EGR valve fault, but that air would be no use in supporting combustion so the fuelling would be awry.

 

Luckily the EGR on these engines (Mk1? What year, engine code?) has position feedback, so if the ECU logs enough 'mismatches' between where the valve is commanded to be and where it actually is, you'll get a fault code and warning light.

 

I bet there's about half a dozen different scenarios that could lead to the same behaviour though, so don't suddenly start condemning your EGR valve. In fact, if your engine is code BME, late Mk1, it may not even have one! 

It's an 04. I might see f I can get the guys at Halfords Autocrntres take a look and mention what you have said. I'll at least be able to see if there are any fault codes for a start. Thanks for your help. ps I work for then so they should hopefully look after me.

It was the spark plugs causing the hesitation. All sorted. They said coil pack initially but after investigation that was fine.