Boost gauge not reading vacuum.

[JimX]

The other day I noticed my Autometer boost gauge would sit on around zero or -1 or -2 psi when my foot was off the accelerator. It used to read much lower than this. My EBC still reads -0.5 bar like it always has. I also noticed that my factory gauge which is still hooked up into the same line also reads around the same as the Autometer one, when it also used to read lower for more vacuum.

Going off the EBC's reading of -0.5, I should be getting around -7psi or so, it in fact used to read anywhere between -10 and -15 or so on the Autometer under vacuum. Does anyone know what might have happened? I don't think the gauge itself is at fault otherwise the factory gauge would still be displaying more vacuum like it used to.

As far as I know it's still reading correctly when under boost, but I haven't had the chance to floor it lately to be absolutely sure.

[blind_elk]

Sounds like a leak (break, pin-hole, etc) in the line between the manifold and the gauges.

Must be a hill around somewhere for you to gun it in 2nd to test the boost reading.

[JimX]

Yeah I think I'll trace the line on the weekend. I was thinking it must be a leak but then wondered why it would read positive at all. It must be easier to suck than blow through the hole

[skylineakt]

That happened to me too JimX. The vacuum was sitting very high even when decelarating.

The cuprit was the rubber hose that joins the T pipe. It was split pretty bad. So I cut it back and reconnected.

2 weeks later runing high boost it happened again, split, cut back and reconnect

1 week later split, cut back and reconnect but to the point where I was running out of rubber hose. So I decide to buy some new hose altogether and refited. Now no problems with it splitting when running higher boost.

If this becomes a reaccuring thing JimX, I think you should just replace the rubber hose.

Cheers

[JimX]

Thanks for the info, we seem to have it nailed down then. In fact I'm gonna go take a look right now and see what I can find!

[JimX]

Woot! Found it. The hose on one of the t-pieces had huge split because basically it wasn't wide enough to go on. It was permanently under stress and so eventually split. I'm looking at using some small plastic hose as a go-between for the t-piece and hose. Should be ok from here.

Thanks again for your help guys.

Edit: Tested car, all works fine. Hope the split in the hose didn't suck too much dust into the engine!

[skylineakt]

SERIOUS!! I didn't even think about it sucking too much dust into the engine!! Damn shouldn't of have told me hehe. It is cool. Everything is still running fine.

Is the hose the original hose JimX?? Mine old hose was very stiff and it just keep spliting. Maybe better just to change to new rubber hose instead.

[JimX]

Nah it's some new aftermarket hose that (unnamed workshop) used when reconnecting the boost gauge that I ripped off my steering column as soon as I got the car. I didn't have a problem with it being on the steering column, except it was blocking too much of my tacho because it was too big. It's now in the much more sensible A-pillar location. The only problem with the hose is it's too small for the last t-piece going into the plenum.

I think my engine will be ok for dust. It's only been doing this for the past week or so (driven 2-3 times) and I haven't been driving through any dust storms. If anything the recent rains have kept the dust to a minimum. But I'm definitely going to keep a closer eye on it in future.

[blind_elk]

If it's plastic hose (as distinct from rubber hose) simply immerse the end in hot water (to soften the plastic) before slipping it onto the T.

[JimX]

I managed to squeeze the tube in a few millimetres, but if it pops out I'll try your hot water suggestion. Thanks!

Hehe, if anyone with the same problem is worried about getting dust in their engine before they get a chance to fix it, just keep the turbo on boost all the time to keep the dust out