MAP Vacuum
 

I was looking in a vacuum diagram for a 1989 5.0 I looks like the MAP Vaccum goes to MAN VAC. I am assuming MAN VAC is considered the VAC Tree. I hooked my the Vacuum line running out of the MAP sensor to the tree labled B/R. Is this correct?

Thank you,


Mountain Main

Please Reply.
 

Please check out your car and reply.

Mountain Main

No, it's not the tree but that should work. The stock location is to the manifold directly on a dedicated port.

The Vacuum Tree
 

I tried to use the vacuum tree and it pulled the same code. Where is the connection on the manifold at. What is it located near?

The Diagram
 

Makes it look like the MAP vacuum connection with the intake manifold is right next to the Fuel Pressure Regulator's connection to the manifold.

Thank you

Mountain Main

I don't have a picture to show you, but it is a line that comes directly out of the intake. The vacuum tree is not as good because you have vacuum devices (like the power brake booster) that can vary the vacuum signal in the tree more than the intake.

If you use a line from the manifold and get a code - you might have a bad MAP or vacuum line to it.

Thankx
 

I will be looking for that vacuum nipple. If any one can tell me what general location it is in. Please Post

Mountain Main

I found the manifold vacuum source
 

I think I found the intake manifold vacuum source for the Map. It is on the back side of the intake. I am not able to get to it. I spent four hours trying to take some cap off of it. It will not release.

ths might be a dumb question ...but if you going off an 89 diagram wouldn't that make it a mass air system

if your running a mass air computer then the map does'nt get hooked up to any vacuum

if your running a speed density car the the map should be t'd in to the vacuum at the center of the intake (t it into where your feul pressure reg drawls vacuum)

My car has Mass Air and it is not a conversion.
 

Is this really true about the Mass Air Cars don't need a vacuum connection to the Map. My diagram says that there is a hook up for the MAP sensor. Please speed density and mass air guys please respond.

yep...mass air computer cars only use the map sencer to read baromertic pressure

as long as you have a mass air meter then you don't need a vacuum line ,the map sencer for both cars are identacal parts and can be interchanged .....but the map sencers for mass air cars have a little plastic peice on the vacuum input to avoid a vacuum line being hooked up to them ......but it still is the same part

a mass air car measures engine load via the air passing though the mass air meter ,but it will use the map sencer to determine the baromertic air density for tuning reasons (measures altitude ,barometric pressure,ect) .......it only takes a reading from the sencer when you start the car.....then it moniters the mass air meter to determine engine load

now a sped density car uses the meter to measure barometric pressure and to measure engine load ......it takes a quick reading when you start the car up and then it uses the meter to moniter vacuum levels so it can determine how much load the engine is under .....

hope that helps to explain ,as far as i know there isn't any call for a vacuum line to be hooked up on any of the mass air computer cars (89 to 97)

Thank you
 

I appreciate the info. I have been looking for that vaccum line for a while. Did some of the 1989 5.0 EFI come with Speed Density?

All of the 89 & up Mustangs should be Mass Air. Speed density was discontinued on the Mustangs after 1988. (1987 in California)

86-88 use MAP(86-87 in cali) and 89-93 use BAP(no vacumm hose)

Re: My car has Mass Air and it is not a conversion.
 

I didn't remember your car being MAF, I'm sorry. I always refer to it as a BP in a MAF engine, and a MAP in a SD engine, so when someone is asking about a MAP sensor, I automatically start thinking SD. I've been really busy lately. lol.

What concerns me is why your schematic would show a vacuum line going to it, though.