leaking plenum

[mattp VSII]

hey guys i was just wondering if a small leak in the plenum could be affecting idle and power. planing to fix the leak anyway. also is it worth pollishing the inside or just clean it???? thanx

[neet_wagon]

A leak of what exactly?

[mattp VSII]

air sorry forgot to mention that

[neet_wagon]

Yeah, it'll effect idle, power, fuel economy.

As for polishing it:
There is a school of thought that shiny isn't very efficient.
Clean it, and make it smooth-ish. Hard to explain, just keep a grain in it.

[_R_J_K_]

Hard to explain, just keep a grain in it.

Atomization?

[neet_wagon]

Atomization?

Do you mean should you keep a grain in the alloy to aid atomization?

I don't follow sorry.

The train of thought is the same with porting heads, neat and tidy heads will flow more efficiently than heads ported exactly the same, but with a polished finished.....

[mattp VSII]

yea i was under the understanding that the grain caused the air to ripple or swirl this helps it to mix with the fuel better. this is why i was asking because ive heard pple talking about pollishing.
thanx ill fix the leak and clean the insides up, and let you know how i go

[neet_wagon]

No worries.
Yeah thats the way it got explained to me also

Good luck!

[HamaTime™]

Does it make a wooshing sound of escaping/leaking air when accelerating? Idle slightly rough? Cold start very rough?

[mattp VSII]

yea you can hear the air escaping from the plenum lid where the rubber gasket is, the idle rpm varies from 900 to 2300 almost like the tb is sticky. and yea idle a bit rough

[HamaTime™]

Hmm it sounds slightly like my problem. I got escaping air coming out somewhere, idle goes down to around 4-500 and is shaking as if it is about to stall. Escaping air while accelerating as well.

[_R_J_K_]

Do you mean should you keep a grain in the alloy to aid atomization?

I don't follow sorry.

The train of thought is the same with porting heads, neat and tidy heads will flow more efficiently than heads ported exactly the same, but with a polished finished.....

Yes that's what I meant, and that's what I was under the impression of too. Although I have heard when porting heads, keeping the intake "grainy" whilst polishing the exhaust can be beneficial. I don't know anything about porting though, so I don't know if it's true or not.

[HamaTime™]

Check the hose underneath the throttle body. Might have come undone? Does it backfire?

[mattp VSII]

ok ill try that thanx mate. and no it doesnt back fire