UrS6 - 'Free' additional bhp - have a read to check

[macspring]

Glad the post had some traction.

Just for clarity, I think the reason for the major improvement in my car was the replacement of the bypass valve, rather than the small little vacuum pipe that leads from the 'top' of the bypass valve to the small metal pipe that sticks out from behind the cambelt area.

I started on the job with the idea of replacing this original 'rubber' pipe, (1997 = 18 years of heat cycling), which had become hard and stiff, with the two respective ends able to be rotated by hand easily. But in the process of trying to get it off without breaking anything I took off the by pass valve and when I tried sucking on it, it didn't seem right, so I tried an old one from the garage and the car is hugley improved. While the pipe was replaced, I think it is all / 98% down to the bypass valve. Your experience may differ, but replace both the old vacuum pipe and the by pass valve and you should be golden.

Be sure and orgainse either small jubilee clips for the re-attachment of the new vacuum pipe at either end, or the 'one use only' oem style crimp to tighten, or zip ties if stuck in the ghetto.

HTH.

[newsh]

This is really basic stuff guys. The DV has to work properly with diaphragm intact and the actuator vac pipe must be leak free.
If you can't get vacuum when you suck on the small tube then the diaphragm is split which leaks boost back to the face of the turbo and means the DV doesn't open properly on lift off. You might hear a chattering or duck quacking type of noise if this is the case.
If the small tube is leaking then the DV will tend to open on boost, effectively connecting the output of the turbo back to it's input, overworking the turbo and leaking boost pressure...

[newsh]

@macspring

Have you checked/replaced the two pieces of small bore vac tube from the inlet manifold via the small hard line to the FPR?

More free BHP to be had there

[imp998]

newish, omg, more bhp, I can't cope!

[macspring]

This is really basic stuff guys.

Fair enough, but the members are at differing levels of expertise.

Also sometimes one doesn't realise something is wrong - 'Can't see the wood for the trees'.

My car was working but not properly, but I didn't fully appreciate that it was as off as it was as I got used to it, and so when the bypass valve was replaced the car was much better.

Just sharing my experience for who ever it benefits.

[newsh]

UrS6 - 'Free' additional bhp - have a read to check

Agreed and no offence, good to bring the issue to the fore. I was just trying to add the reasons for why this component is so important, it's surprising how often they turn out to be broken too. Basically it should be treated as a service item, especially if the car is chipped.

[newsh]

UrS6 - 'Free' additional bhp - have a read to check

How about the Fuel Pressure Reg vac tube then? [emoji6][emoji6]

BTW for vac tube I use small bore silicon bought by the metre from eBay. The best clips are Oertiker

[macspring]

Agreed and no offence,

No worries, none taken.

Didn't think of it as a service item, but do from now on.

Will do the fuel pressure regulator pipe as soon as it stops raining.





Hard to surf while kids are asking me to look at their present. No consideration for my feelings.

[newsh]

[Vorsprung durch Technik]

Hard to surf while kids are asking me to look at their present. No consideration for my feelings.