Check valves = boost leak?
 

Why wouldn't it be better to put the check valves in series with the arrows pointing toward the throttle body instead of venting them to the atmosphere?

Re:Check valves = boost leak?
 

the whole point of checkvalves (on an fmu setup) is to vent off boost so the map doesnt read it

Re:Check valves = boost leak?
 

The valves are one way...right?

If you put them in-line...Wouldn't it do the same thing but without the leak?

Re:Check valves = boost leak?
 

yes...but ive never used checkvalves so im just speaking theoretically

Re:Check valves = boost leak?
 

I have tried it. It dosnt work. Just enough pressure gets past the valve before it closes and it sets the check engine light. What I did was use a check valve from the smog era chevys. it has one port on one side and 2 on the other. on the side with 2 ports you connect the map and a check ball type valve that is adjustable. when the valve sees boost it closes and the other check valve opens letting out any pressure. Plus the map is reading
the atmospher outside. Its not perfect but it works.

Re:Check valves = boost leak?
 

yea i guess the movement of the valve as it closes puts enough pressure on the map to trip a cel...hmm

Re:Check valves = boost leak?
 

i think thats y u add more check valves ;D, iseen a guy runing 6 check valves to stop a code.

Re:Check valves = boost leak?
 

what about this idea? just drew up a quick diagram...
http://www.shownglow.com/2-cv-idea.bmp

Re:Check valves = boost leak?
 

looks good to me, but ive never done anything like that

Re:Check valves = boost leak?
 

I haven't either.

I'm not planning on using an FMU set-up, but the thought just came to mind.

I think that if you put several in series it might work.

I'm not sure of how much of a benefit one would gain by using the check valves in this way, but it seems that it would be better to have a system that doesn't have a boost leak as part of the design.

Re:Check valves = boost leak?
 

what the hell is this thing? how is the map supose to read any vacuum? am i missing someting?

Re:Check valves = boost leak?
 

how would it not read vacuum? you are missing something, or i am :P

Re:Check valves = boost leak?
 

It will read vacuum, but I'm suggesting using several in-line without using a "tee" at all.

We need a volunteer to try it.

Re:Check valves = boost leak?
 

This would seem to be an improvement over the widely used system of venting to atmosphere. It = less boost leak for sure.

Re:Check valves = boost leak?
 

wouldnt the check valve thats coming from the vacuum source close when boost hit?

Re:Check valves = boost leak?
 

It will work if the green arrows indicate allowed air flow.

It would work better if the "tee" was before the first check valve.

Re:Check valves = boost leak?
 

exactly, but air doesnt come from the map, its goes towards it. so when boost hit, the check valve would close. that just looks like trouble.

Re:Check valves = boost leak?
 

Don't you want it to close? Ya know...so the MAP doesn't read boost.

...and no boost leak.

Re:Check valves = boost leak?
 

dude no ----. i was thinking of some other ----. my bad. ya then it looks like it will work perfect. i was thinking about my setup. im using the afc plus one check valve so i can boost past 11psi with no cel. so i need some boost to get to the map but not all of it. OOOPS!i think im gona go to bed now. :'(

Re:Check valves = boost leak?
 

It's cool man... All these check valves and airflow directions can be a bit confusing.

I have to think twice about it also. hehe

Re:Check valves = boost leak?
 

won't work, i have tried it, you just have to do it the normal way and get over your ideas.

Re:Check valves = boost leak?
 

I've tried it too, it doesn't work. Having the check valve in line won't let the map sensor read properly..

Re:Check valves = boost leak?
 

damnit!!!! in thinkin bout maybe crimping down the line goin to the map a lil so not as much boost can get to it/ecsape with the check valves... not that its really hurting performance, but i dont wanna lose even 1 cfm if poss. hmm...

Re:Check valves = boost leak?
 

i dont see how you would be loosing boost with a check valve. its a one way valve (as mentioned) that only bleeds positive air pressure, NOT vacuum. if the check valve was placed right before the map sensor (most times you need more than one) you shouldnt be loosing any pressure going into the Throttle body. all thats doing is just stopping the map from reading positive air pressure, if your map is still seeing boost with a check valve, you either hooked it up wrong or its faulty. im not sure what kind of check valves your using, but i've personally found that fish tank valves work the best.

Re:Check valves = boost leak?
 

88 turbo crx: Nods in agreement

Re:Check valves = boost leak?
 

i've tried the method shown in that picture and it doesn't work ('99 corolla stock map sensor). it'll idle for about 30sec and die on it's own. if you give it any gas it'll also die. used in a config. where they actually just bleed boost, it works but YES you're bleeding a little bit of boost so you might get a bit of lag.

Re:Check valves = boost leak?
 

you lose boost (very little, but still) because they dont work inline...they have to be hooked up so then vent pressure off and away from the map...so basicly its venting pressure from the map sensor line to the atmosphere.

Re:Check valves = boost leak?
 

ya thats the point of the check valves. any boost in the vacuum lines is unused. justbecause its venting before your map doesnt mean your not going to see full boost. the only boost that matters, is the boost running through your charge pipe into your intake manifold and then into your cylinders!

Re:Check valves = boost leak?
 

but the map is before the cyl's, so therefore any boost being vented at all will be taken away from going into the cyl's. the amount might be minimal as all hell, but still.

Re:Check valves = boost leak?
 

anyone have experience with the missing link? any good?

Re:Check valves = boost leak?
 

May be the check valves place in-line, cause a problem in the way that the MAP sensor reads vacuum.

They might cause enough resistance in the airflow through the line to prevent it from reading vacuum correctly...I don't know.

But even if it won't work to place them in-line, there's still nothing wrong with questioning the "old way" of doing things.

This is how we find better ways of doing things...or even if it's possible.

It keeps us thinking.

Re:Check valves = boost leak?
 

I've heard that the Missing Link works well.

Does anyone know if it vents to the atmosphere?

Re:Check valves = boost leak?
 

Yeah I orginally had them like in the picture and I couldn't figure out why my car wouldn't idle. The only plausible reason is that the check valve is like a resistor and reduces the vacuum that the map reads. Either that or it delays it. Anyway, I think the missing link releases to the atmosphere. I'm willing to pay $70 to see if it works better than my check valves. I'm such a sucker :P

Re:Check valves = boost leak?
 

I ran a Missing link till i went with the afc hack, worked like a charm, never had any problems with it at all!

BTW its still for sale and looks and runs brand new! ;D