BOV/WG connection with 3.2 intake
 

I'm just finishing my EFI conversion + rebuild and am going with the 3.2 carrera intake.

My question is: where can I tap into the throttle body to get a boost reading?

And for the BOV connection, can I share this same line (which will be used by the ECU, gauge and likely WG)?

thanks.

You can tap pressure signal for BOV wherever you want after the throttle. Reason for this is that BOV needs vacuum signal in order to open. You don't need to tap into throttle body, you can tap into plenum itself.
Same goes with MAP-sensor, it should get the signal from plenum.

Wastegate signal should be taken before the throttle, in order to expose the wastegate membrane to positive boost only.


Do not use same signal line for both BOV and MAP (by T-orifice or such). BOV's often leak and that would affect pressure in pipe and thus alter readings of MAP sensor, ruining your motor in worst case.


To conclude:

MAP & BOV: separate lines from plenum.

Wastegate: line from intercooler, compressor housing, tubing...whatever, just as long it's before the throttle.

Thanks for the help Goran...

I noticed that there's a 1/2" fittiing after the throttle plate for the air valve (which I'm not using), and there's a vacuum hose port above the one for the FRP/damper.

So I think I can use one for the BOV and the other for the MAP sensor?
The vacuum hose port is really small - would that be ok for the BOV?

For the WG - its driven by my profec B controller. I should double check if I can tee it off the same port with the MAP sensor where it will see vacuum.

hobieboy, Do you know what the thermo valve and air valve your talking about do? I planned on getting my BOV signal from one of those ports, but I'm at a loss for understanding what those valves do for motronics. I have to use one of those other ports for an FMU I'm mounting. Or tee it off or something.

Jerry, not 100% since I'm only using the intake/throttle body for my EFI conversion.

My understanding is... the air valve is emission related?

Here's my set up. I haven't run it yet so I can be sure it's going to work, but I'm getting the BOV and fuel regulator vacuum from the two ports on the back of the TB and the MAP sensor signal from the large port on the back of the intake since I'm not going to have an air bypass. I'm getting the WG pressure from the inlet tube from the intercooler to the TB.

http://forums.pelicanparts.com/uploa...1152826340.jpg

Here's a shot showing how I got the signal for the MAP sensor. I was going to have my atmospheric MAP sensor on the engine, but I've told I should put it in the passenger compartment so I'll be moving it. I'm also going to make a new bracket for the MAP sensor so it lies flat with the port facing down.

http://forums.pelicanparts.com/uploa...1152826407.jpg

I believe you missunderstood things.

Connecting WG to a T-orifice off the same port as MAP is very last thing you should do. Especially if electronic boost controller is involved.

Forst of all, you shouldn't T anything, especially not the wastegate.

Wastegate should be connected to pipes before the throttle. Only thing electronic boost controller does is to modulate the pressure going to wastegate by blowing it off with magnet valve. When driving, your Profet T-Diddy Ultra Modulator will start blowing off air in signal line going to wastegate in order to raise the boost over base boost imposed by the spring. If you happened to Tee this line with MAP-sensor, your ECU will suddenly start believing that your boost is much lower than it is. It will inject less fuel into engine and boom, your pistons are shot.

Sensor eqipment (MAP-sensors) can be connected to thin lines as they esentially only sense the pressure and don't really have any flow.

Pressure-operated eqipment (wastegate, BOV) should never be T-connected into any of sensor lines, as they frequently leak and alter the readings.

The very worst scenario is the one you described above...connecting pressure-operated and deliberatly leaky equipment on same chain as vital MAP-sensor.

Wastegate doesn't need vakuum...actually most of times it's just unecessary to feed it with vakuum as it will expose the membrane to greater pressure differential than if connected before the throttle (and thus never expiriencing vakuum).

Thanks guys... so it sounds like I can use the 2 ports (1 big, 1 small) in the back of the throttle body for MAP sensor and BOV as David did.

I was going to tap into the output of the intercooler for my IAT so will add another nipple for the WG/boost controller then.

This sounds right?

I would not use the port on the TB for the MAP sensor. If you're going to use the large port on the back of the IC for an air bypass, then I'd add another port on the intake away from the TB so it gets a good pressure reading that's not affected by air rushing through the TB.

For the WG, I'd add another port to the inlet before the TB.

David,
Have you started the car? How does it runs without the idle air valve? Maybe I should use that same "hole" as you are for the MAP sensor then.

Will use the large port at the back of the TB for the BOV.

My IC does not have any nipples/port so am going to add a couple for the IAT and WG.

I haven't started it yet, but since I live in the south I don't expect a problem. If you're up north you're probably better off using one so it'll start OK in cold weather.