I have the car on the road after having MB motorsport sort a few issues out.

I took it for a drive to the lakes over the weekend and noticed some odd DV behavior that may indicate a problem or could just be that I'm not used to this car.

When I back off the gas during part throttle I get a "cha cha cha cha" sound rather that a single ****hhh like I have on previous 1.8Ts I've owned. The car has a Bailey DV vlave.

I also get a N249 mechanical malfunction error in vagcom but that may be normal as I think the N249 was already bypassed on my car (I need time to check).

This is a new turbo as the old one cracked so I'm a bit paranoid that the problem that caused that to happen may not have been fixed.

Any advice much appreciated!

Ron

Sounds like the N249 valve has gone, or if you have already bypassed it, then one of the hoses in the bypass setup is either blocked, kinked or restricted. If the DV is a piston type it might also be worth taking it off and checking the piston moves freely, lubricate it with some red grease if not.

I'd take it easy until you get it sorted out, don't drive around at full boost and let the throttle up gradually instead of snapping it shut. the "cha cha cha" sound you describe is boost being forced back through the turbo because the DV isn't opening quick enough, if you have a big turbo running higher boost pressures it's a good way to damage the shaft and bearings of the turbo.

Edited 13 July, 201015 yr by chicken_eyebrow

Cheers, I'll take a look at the DV piston.

I've got it booked into MB on Sat although having talked to Mike on the phone he didnt sound too concerned. Problem with having the induction kit is that ther car makes all kinds of sounds and as I have had modded 1.8Ts in the past but with the standard airbox, I have nothing to measure it against. Also the N249 error will be there if the N249 is bypassed regardless of it working or not.

Just to clarify.....the "cha cha cha" isnt mechanical sounding, but it is like 3-4 little DV bursts rather than one big PShhhhhhh like I would expect to hear.

Luckily it was a family holiday with the baby in the car so I was taking it very easy so likely no harm done.

Turbo has barely covered 500 miles so far.

Ron

Just to clarify.....the "cha cha cha" isnt mechanical sounding, but it is like 3-4 little DV bursts rather than one big PShhhhhhh like I would expect to hear.

If it sounds like this then yeah, its compressor stall (boost trying to go back through the turbo)

Not much to worry about, I'm sure the garage will find out whats wrong either the DV or the pipework is my guess.

You can get rid of the N249 error code if you've bypassed the N249 by fitting a 330ohm 10W resistor into the multiplug so the ECU thinks it's a working N249 valve.

Hmmmmm thats a very useful link, thats not what my car sound like. I get a Psssshhh and then some secondary whistles but they are much softer than that chattering sound from the car in the link.

We'll see what Mike says but I'm starting to think it may just be normal.

Thanks for your help!

Ron

Sussed it, went through all the vac lines as they all looked pretty old and replaced with Silicone ones. 2 had rubbed through and also my rocker cover breather hose is split.