Club 80-90 Forums

Hi all, need to resolve something that's been bugging me.
I have a scan gauge that reads my turbo boost, on hard acceleration it instantly hits about 15 to 16 psi, then drops immediately down to about 13.2psi. Doesn't seem right to me. I've done some trawling and I gather boost is meant to increase and peak at a max of 18psi, not decrease. Could I have a leak of some sort?
How does others behave?
Appreciate any help

Just to ad my details in
Foot flat to floor, boost peaks for a few seconds at between 15-18psi, sometimes 20psi, if my foot stays down it normally settles at 13.6psi and will stay there until the load on engine changes. Occasionally it will go higher, to say 14.5. But as I said, 13.6 psi is my usual. I've just fitted new vacuum pipes, maybe it will change a bit now?
Don't think you will have a boost leak as it would keep on dropping I reckon. It could be a stiff actuator on the vnt not allowing full movement? I'm getting a new turbo shortly, will be able to let you know if it changes.
You also have to take into account pressure drops through the charge cooler and pipework, my charge cooler has a rated 0.1psi pressure drop, yours might be more.
Does it feel like you've lost power then? Or is it just that you have started looking at it

I could have a boost leak though, as I am leaking oil from my boost pipes I noticed today, and if oil can get out so can air I suppose.

Cheers Lloyd, never had the boost showing on the gauge until recently. Just been watching it. From what you've said, it's probably fine then. Looked on the tdi forums previously and it looked like mine wasn't working right. Will check everything anyway.

With VCDS measuring blocks you can check actual against specified boost pressure. If they are pretty close then everything is good.

To update, I went out last night in the van. It did not feel as powerful up the hills but boost was still at the 13.6 but started to drop... Had a look when I got home and my boost pipes have sprayed oil all over the left hand side of the engine so new turbo. Only posting this on this thread as I must have been losing boost pressure. When I get the new turbo fitted and clean the pipes up I'll post what I get. (although I have found a old pic of the van going up Reigate hill on the m25 showing 15.5 psi boost. So might be worthwhile checking all the joins on the boost pipes, you might have a slight leak

More bad luck eh?
Cheers for the info.

It's been passing oil since the beginning, has got a lot worse over the last couple weeks. Used to find oil in the boost pipes but never enough to drip out. That side of the engine has a oil sheen (almost like condensation but oily) all over it. Only noticed it when doing the vacuum hoses. So I reckon it's been spraying an oily mist out of a joint when on boost. Worst case, New turbo £350 or if mine can be rebuilt £250

Sure you don't have split pipe? Shouldn't be any way for oil or air to get out of the pipes...

max and caddy wrote:Sure you don't have split pipe? Shouldn't be any way for oil or air to get out of the pipes...

I was getting oil leaking from the joints before I replaced the turbo. I had a look earlier and they now look dry.

From the joints is understandable...but if its spraying up the block!..maybe it's not as bad as it sounds..

maybe i made it sound worse that it is.. where its leaking oil from is the joint either side of that MAP sensor from other thread

the underneath of it is wet with oil, i think what is now happening is oil is leaking from those joints, when on boost, boost leaks out due to them not sealing correctly due to the oil, the boost pressure is mixing with oil to make misty boosty air which is settling on the other parts on that side of engine... also noticed this evening that oil is now dripping out of the turbo housing. need to get myself a good big bore oil return

lloydy wrote:maybe i made it sound worse that it is.. where its leaking oil from is the joint either side of that MAP sensor from other thread

the underneath of it is wet with oil, i think what is now happening is oil is leaking from those joints, when on boost, boost leaks out due to them not sealing correctly due to the oil, the boost pressure is mixing with oil to make misty boosty air which then turns into yeppow which is settling on the other parts on that side of engine... also noticed this evening that oil is now dripping out of the turbo housing. need to get myself a good big bore oil return

love the 'misty boosty air' edited for you
mm

Be intrested in seeing just what that bit of pipe is....is it beaded or just shoved in the hoses?

max and caddy wrote:Be intrested in seeing just what that bit of pipe is....is it beaded or just shoved in the hoses?

i think you can guess there will be no bead, i have the complete pipe on the 'other' engine, no way of getting a bead on it. Reckon when i take it off to fit the other pipe/manifold it will have just been sawn through