A few questions about vaccuum hoses
 

Hey guys, I've just got a few quick questions about the vaccuum hoses on a MY00 UK Turbo 2000 Impreza. For about a year or more, I've had an ongoing not-quite-performing-right-combined-with-horrific-fuel-useage issue (I get about 175 miles to a full tank, when driving like an absolute granny!). As one of my 'experiments' to try and rectify the problem, on sunday I changed all of my vaccuum hoses for new ones, just incase I might've had a leak in any of the original ones. The hoses I bought were SFS 3mm ones from scoobyworld. It says they are suitable for high pressure applications (I don't really know if the vaccuum hoses on an impreza are under high or low pressure, but I thought get high pressure ones to be safe like), and also they were on scoobyworld, so I thought they are bound to be suitable for Imprezas! Anyway, they arrived, and they were like a roll of elastic pipe?! It's sooooo bendy and stretchy, how the hell are hoses like that meant to accurately contain any sort of pressurised air for sensors to read etc!!? Anyway, I just changed them all and went with it, then went out for a spin. The car was worse. Didn't seem to pick up as well, and just felt a bit under-powered. Boost was still showing at normal levels on the boost gauge tho? Before you ask, yes I definitely connected the hoses up correctly. I replaced them one-by-one, rather than taking them all off and bieng like "hmmm, where does this one go??...".

So I have three main questions....
1. Are the standard vaccuum hoses on the car really hard & stiff because they are meant to be like that? Or is it because they are 14 yrs old!?

2. Are those SFS 3mm ones I've got acatually any good? Are they even the correct size?

3. If the SFS ones are no good, where can I get correct ones from and what size etc?

Thanks guys :thumb:

The fact they are more stretchy is probably because the material is different. The old pipes would have been a rubber and not silicone. Age heat and uv will have also hardened the old ones.

It's not really a case of them stretching when you pull them. As long as they maintain their internal diameter at the pressures they are working at they will be fine. The pressure you apply to bend them is probably far more then the 14psi or whatever inside them.

Did you replace the restrictor pill in the new pipes?

This.
Also, have your checked that none of the new vac lines are kinked since reinstallation? :wonder:
Paul

I've learned from this problem in the past! I am on a 3-port boost solenoid now, and Alcatek ECU, and I believe there is no longer a restrictor pill? But back when I was on the standard ECU with the 2-port and I accidentally got rid of my restrictor pill, the car would only boost to around 12psi rather than it's usual 20psi. So the difference was massively noticeable, whereas now it's only slightly. There are definitely no kinks, but some of the lengths may be an inch or so longer or shorter than the original pipes and I'm guessing that may affect it marginally?