With my continuing strange turbo issues, I used a vacuum guage that my father had on the output of the n75 valve of my octy. Prior to doing tis, I had removed the vacuum pipe to the pipe and sucked down it a few times and seen the exterior VNT mechanism move a bit. Then drove down the road, and upon hitting about 2500 from in 2nd the car stuttered a couple of times, and it did the same again in 3rd. :confused: When I got back home the car stayed there for about 5 hours, and I checked for codes there was the standard "positivite deviation" error. I cleared that, and then using this guage, which I believe measures in inches of mercury

The first time I tried this, the readings were not consistant (large jump, and that happened with this relay clicking too), and then when I noted the values the relay clicking had stopped. Figures are:

increasing revs:

idle: 20

1500rpm: 17

2000rpm: 14.5

2500rpm: 13

3000rpm: 12

second run, with decreasing revs:

3000rpm: 12

2500rpm: 13

2000rpm: 14.5

1500rpm: 16

idle: 20

When the relay clicked (as rpm hit 2500), it seemed that the vaccum dropped dramatically, and then picked back up once the rpm drops below 2500 again.

What I don't really seem to understand is that maximum vacuum seems to be applied to the turbo mechanism when at idle, and as the revs increased, the vacuum drops off. For some reason I assumed it would have worked in the reverse of that.

Anyone got any readings of this? I do work with someone who has a 110TDi (pre-face lift), so I might see if he will let me plug the guage into his car one lunchtime and see what happens....

The vacuum is working against a spring, so the vacuum is bled off and the VNT mech shuts up.

This means in theory the system fails safe to the lowest boost setting.

The vacuum is working against a spring, so the vacuum is bled off and the VNT mech shuts up.

This means in theory the system fails safe to the lowest boost setting.

That makes sense for the figures that I saw. I am wondering if my VNT part is fine, and it is a vacuum / electrical issue (hense the relay clicking when cold)? I can suck on the vacuum pipe and get it to stick to my tongue and so that suggest the pipe down to the actual turbo is fine.

Well, given that I don't have the clicking relay, and have so far had a boringly reliable car... >.

Mine has always had the clicking relay - at least for the last couple of years that I have noticed it, I have changed the 109 relay and it still happens but only when cold. It seems to me that the clicking relay is normal operation when the engine is cold. It isn't very loud so you may not notice it especially if you have the radio on.

I only usually have the stereo on; I often switch it off when I have passengers.

Generally I hear mine when the temps are a bit colder, and I normally have my stereo on however. Pretty sure my stutterings have only happened on days when the relay has clicked, but I can't be 100% sure of that.

Wanna swap cars then Ken?!

Well me playing with it over the weekend seems to have made it worse, as I have had "limp home" mode every time since I have driven it since. Grr.