Morning all. In the last few days I have noticed that the dump valve on my car has changed in sound. Firstly it is slightly louder and secondly it sounds more like a rally cars tsss,tsss,tsss (blow off valve?) than just the standard tsssssss. I rather stupidly fitted an induction kit to it 2 weeks ago and then took that off 24 hours later as I hated the chavvy sound and heat soak. Anyway, the day after I refitted the standard airbox my bird went up to see her uncle in Sussex. On the way up the pipe that goes from the dump valve to the turbo fell off. The car went into limp mode and lost power but no warning lights came on. Her uncle refitted it for her (after 40 mins drive)I think that this may have been around the time the dump valve started to get noisier. Have I wrecked it (its a forge 007p btw) or is it something more serious like the turbo or wastegate?

Dan

Your N249 valve is possibly broken. If you do a fault code scan you should get the code 17608 (boost control valve mechanical malfunction) if this is the problem.

The N249 normally assists the operation of the divertor valve by providing a vacuum on the small connection at the top of the DV. If it fails then the only thing that will be making the DV open is the pressure of the excess boost, so the valve doesn't open properly and a lot of the boost ends up trying to go back through the turbo giving that chattery noise.

I wouldn't recommend running around like that for weeks and weeks as it is putting stress on the turbo.

Your options are to either replace the N249 or to bypass it, bypassing it involves re-routing some pipes but I did it on a mates car the other week in a couple of hours, he had exactly the same symptoms as you. Rob Clubley has done a guide on www.pimpmyskoda.co.uk.

Also might be worth taking your 007P off and checking the piston inside is moving freely, if it is stuck then this would cause the same symptoms.

Edited 9 July, 201015 yr by chicken_eyebrow

Hi Dan

I dont think it will have wrecked your 007P....but why not take it apart and have a look.

Its very easy to do, just screw the top off and take the spring and piston out.

Check the "O" ring seal is OK and the piston is free to move in the valve body and the valve seat is in good order.

Clean all parts, lube the seal with a suitable rubber grease and re assemble.

Bill.

Cheers for quick replies.

Chicken Eyebrow - I already have N249 bypass.

VRS180 - I might have a look at doing that if its not too difficult. I think I still have the old bosch one somewhere also. So might refit that to rule out dump valve.

Could a split pipe somewhere cause the noise?

Edited 9 July, 201015 yr by octydan

If you've already done the bypass then check all the pipes involved in the bypass for splits, especially the one from the inlet manifold to the t-piece and the t-piece to the top of the DV. If they're held together with cable ties then consider replacing them with single-use clips or something a bit more secure.

The tscch-tscch-tscch noise is boost going back through the turbo so something somewhere isn't letting that boost escape as it should be, IMO it'll either be the DV itself or a split hose in the vacuum system assisting it.

Edited 9 July, 201015 yr by chicken_eyebrow

Thanks for the advice Will thoroughly check it tonight.

UPDATE : Took engine cover off and the top hose to the dump valve was squashed down at an angle. Put cover in the cupboard and drove car without and it was back to normal