Tonight, while looking around under the hood, I found a hose that goes from my brake booster to a little valve on the intake manifold into my A15 that looked damaged and flattened. Thinking that this was probably not good, I went out and bought a new hose line, disconnected the old one from the intake and then the brake booster and replaced it, screwing it down on each end with some hose clamps like what was done before. Everything is normal except when I touched the brakes the first time the pedal was stiff. Touched it a few more times and it was better but the engine revs up about 500 rpms from idle...is this normal?

What does the hose do and what is the valve pictured on my intake do?

Just worried I've done something wrong.

Cheers.

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the hose is teh vaccum line to the brake booster, the valve is a one way valve so that the booster holds vaccum

what happens when you hold your foot on the brakes? does the engine rev up and stay up. or does it just go up then back down to normal again?

Okay just tested it and the engine revs only when I hit the brakes and then again when I let go of them, not when I hold them down.

still doing the rev thing. Also forgot to mention that the brake lights won't go off after a swapped the hose too. What do you guys think it could be?

okay found a live wire with a plug going to the battery that might be the cause for the brake lights staying on. If i disconnect it the brake lights go off completely and so do the headlights. If i leave it on the headlights work but the brake lights stay on. Argh. What do i do?

with your mouth blow into booster she might have a split diaphragm

Blew into the hose into the booster with my mouth, not sure it did anything. The brakes light are still stuck on when I connect the battery, very annoying. Tried pulling the brake pedal back and still no luck. I have no idea whats going on. Need help!

As far as the brake lights staying on I'd say its something to do with your brake light switch, go to the brake pedal and look up until you see a switch, might be something wrong with that or might need adjusting. As far as the engine revs I think you have a vacuum leak somewhere as the others have said. Sorry can't be more help.

valve must be in wrong way, pushing brakes is pushing air in to the inlet causing increased revs

the valve should allow the engine to suck air from the brake booster, take the valve out (disconnect hoses from both ends) and ensure you can do that (by sucking on the inlet manifold side) to check it is installed in the correct direction, if it has an arrow that should point towards the motor side not the brake side

eidt[] the brake lights is probably the switch as said above, the brake pedal actually presses this switch in to turn off the brake lights, it may need adjusting but more likely the plastic piece that actually pushes it (part of brake pedal) has perished, these are often replaced with a bolt and nut on the ol' dattos these days

"nice products" do a direct replacement brake switch for B110. part number BS26. spend around $10, and your done.