how do they work ? is it the same thing as a bypass valve ?

 

A check valve is a one way valve. It is normally used to bleed boost before it reaches the MAP sensor. A bypass valve is spring loaded and evacuates boost when you let off the throttle.

 

sorry i did not mean bypass valve as in bov......

i meant like......what is the "missing link" product ?

 

The Missing Link is a high quality replacement for the plastic check valves.

 

how does it work ?

 

When boost is applied to the check valve, it opens and the boost escapes to the atmosphere before the MAP sensor can read it. When the car is under vacuum, the check valve is closed(read one way valve) and allows the MAP sensor to read regular vacuum.
later,
Jared

 

I've always wondered about that concept. If it's bleeding boost into the atmosphere so that boost won't reach the map sensor, isn't it kinda like a boost leak? Cause I know on an RX-7 if you have a boost leak, you're basically losing boost and won't make full boost, so in order to make full boost, basically your turbo has to work a little harder to make up for the leak?? I'm not sure, so please explain.

 

You are correct. It is a boost leak. I'm sure you could fix that by taking the outlets of the check valves, combining them, and routing it back into the manifold. However, it is a small boost leak, only what will flow through the check valves.
later,
Jared

 

yeah basically a small leak but not a big deal. You can make an electronic check valve so to say. since the MAP sends a voltage to the computer that's dependent on the manifold pressure you simply make a circuit that doesnt allow the ecu to see anything more then 2.9v approximately. I dont really know all that much about electronics but G from the board is going to let me try one on my car that he made.

 

that seems like the simple solution.......why hasnt this been done before ? i hear alot of people say they dont like the check valves....

 

That is it, I'm going to make that electronic device that will regulate pass-through voltage from 0-2.9V. I didn't know it was simple as just the voltage. My major at UCSD is electrical engineering. That entire device is just capacitors, diodes, and BJT transistors!! I've made something like that already. That is it, time for some schematics!!!

 

you'll want to check your MAP voltage at atmospheric pressure first, they're all slightly different. for example mine was 2.9, G's was 2.82 or something like that. Just turn the car on without starting it and check the voltage that the MAP is giving out, should be high 2's.