Most Map sensors I have seen on TBI and Carb vehicals allway have the MAP on the fire wall or on the fender. Would the Map get a better signal closer to the intake, IE faster singal and stronger Vaccum signals? Would it be better running it of a TBI port or off the intake? Does too much heat affect the MAP sensor?

 

As I under stan a TB works like a Venturi creating velocity and a partial vacuum right after the constrition, right where the vacuum ports are on the TBI possably giving somewhat false vaccum reading at some RPM ranges. Or am I just worried about nothing?

 

TBI doesn't use a venturi like a carburetor does. Carburetors use this venturi effect to pull fuel out of the fuel bowls, since TBI injects fuel you don't need that. If you look closely you'll see that the bores are strait and aren't tapered at all. Now vacume ports that connect to holes in the throttle bores are what are called timed vacume ports which means that they only get vacume at certain times, when the throttle plates pass by them. You want to connect the MAP sensor to a manifold vacume sorce, which has vacume all the time. One of the vacume ports on the front of the tbi should run down and connect below the throttle bores, this is the one you want to use, you can also use a port that is on the intake intself. As for length of vacume tubing, don't worry about it, some guys have ran like 6 foot of it before to dampen the signal on really harry cams.

 

On big block trucks, the MAP is mounted to a bracket on the intake.

 

I moved my MAP sensor closer. Let's just say that the tube going from the back of the TBI to the map bung is 3" long .
I didn't notice any difference since I was already using rather stiff tubing.

 

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MAP is the acronym for Manifold Absolute Pressure. It reads and reports absolute pressure, not gauge pressure.

RBob.

{edited for spelling}

 

OOps. My bad. I was thinking about another system. I'll delete.