boost leak?

[teknical]

I fired up the sr today, and let it run for quiet sometime. I noticed that the boost guage is reading like 15-20 Vac? which doesnt seem right to me. I gave it a bit of gas up to like 2500-3000rpm, and the boost goes to like 10 vac, there doesnt seem to be any pressure. Was just wondering if anyone could tell me what the problem would be exactly. Also getting a tinkering when the rpms raise a bit. Not sure what that could be :(



Thanks.

[b_t]

There will not be any pressure when the car is just idling. You need to have a load on the engine, and a good deal of rpm to make any boost. In fact, 15-20 vac is a pretty healthy idle by most standards. If you have less then that, something is wrong with your car, or you have big aftermarket cams.

[teknical]

so I'd have to go like 4500-5000 to get some sort of boost?

its been a while since I fired er up, and I dont wanna rev it to full redline while its sitting in the garage, also it hasnt been fired up since mid June.

[b_t]

I can't say for sure if that would make any boost. You need to drive it somewhere.

[EK 2.0]

You would have to be in gear and in motion to make boost...at idle I am not sure about SR's entirely...but you prolly wont see more than 1-2psi when flooring it in neutral.

Also remember that when it's cold out, you will see a few less inches of vacuum.

[teknical]

Alright, ill wait til i get it in the new car, and take it around the block.
Thanks.

[Raz2]

Yes, you shouldn't expect to make boost under no load.
A tinkering could be valves, fuel injectors... Nothing I'd worry about unless its loud... Could be a small exhaust leak?

- Rasmus

[teknical]

k cool, yeah there is a small exhaust leak, but I got that fixed. hope its not injectors, the valves are loud to begin with on the sr, so im not worried about that.

Probably just needs some fluid flushes, and itll be good to go.

[Raz2]

So, are you firing this thing inside a donor car, or whats the deal?

[Boosted_TL]

All these guy's have summed it up correctly. 15-20 in vac is actually a good reading and you have nothing to worry about. But I am curious as to why when you give it 2500rpm's that it wont read 0 and it shoots to 10. It should go to 0.

Example, In the cold my car will read 14 in vac, on a good temp it will read 20 in vac.

And its a Nissan motor, so the ticking is your injectors.

Nothing to worry about IMO, when you test drive the car in normal temp conditions and you come back and say it will only read 12-14 vac, then yes its time to search for your vacuum leak.

[teknical]

well its in my black 240 still sitting inside the garage. I just fired it up today to give it a little warm up and she fired up pretty decent for 5 months of hibernation.

Gonna swap it over this weekend into the new car, see how things roll. Hopefully pretty decent.

[Penguin_Racecar]

a mentioned already, you shouldn't be reading more than 0 lbs of pressure when flooring it in neutral. The pressure you're idling at seems normal too. If you start it when it's cold out (such as now), it will idle at a higher RPM and therefore at less vacuum pressure for a bit until the engine is warmed up and the rpms drop

[dj_rice]

My vac is usually 18-20 InHg, when I had a vaccum leak it was around 10


But congrats on the SR firing up....U know you've missed the boost bug wayyy too long..

[n1zm0]

mine sits at around -.6 bar in idle and up to 0 on neutral rev (i think normal), I had vaccum leak not too long ago, you'll usually know right away, your car 'll run like crap(well for me it did)

[teknical]

Alright, thanks for all the info guys. I'll be starting friday morning bright and early. Once its up and running Ill take er for a spin. If it doesnt boost properly, I probably got a leak.

It ran perfectly fine the day I parked it though, Could something go screwy while it was parked?

[A790]

Originally posted by teknical
Alright, thanks for all the info guys. I'll be starting friday morning bright and early. Once its up and running Ill take er for a spin. If it doesnt boost properly, I probably got a leak.

It ran perfectly fine the day I parked it though, Could something go screwy while it was parked?

It's possible, but not really all that likely. As long as the fluids are okay and it was parked with good oil.