MAP Sensor?

[CTBlaz45]

I need to know what vac lines hook into the MAP sensor. I have one hooked into the front form the TBI. Then I have two ports in the back the larger of the two which is toward the center of the motor goes to the EGR and then there is a second smaller one which goes to nothing. It is stalling alot and this might be the prob. It is an 89 with a 350, and a 700R4

 

[k20]

man I was supposed to look at that for you wasnt I? I 4got all about it man, Ill look on mine tomorow if someone doesnt post up the correct answer here before then.

 

[CTBlaz45]

NO prob. I am just trying to get it good cause my club has our major club camp out run in july. I just got the top off and now I need to rebuild my front axle.

 

[k20]

what you may try lookin at is the smog tag on the core support and following that to figure out what it is. Unless your tag is missing, that may tell you, as memory serves it goes to the tbi, but i am not sure of that.

 

[HarryH3]

I put on my coat and went out to look under the hood of my '90 for ya. (It's freakin' 43 degrees here right now! /forums/images/graemlins/eek.gif What a way to start summer, eh?)

MAP connects to the line coming off the back of the TBI.
EGR solenoid connects to the line coming off the passenger side, front of TBI.
PCV valve connects to the center line coming off the front of the TBI.
Charcoal cannister connects to the line coming off the drivers side, front of the TBI.

/forums/images/graemlins/thumb.gif

 

[CTBlaz45]

What goes nto the TBI is ok it is what goes into the MAP that I need. IT has 3 hook ups one of mine is empty. Is it supposed be?

 

[HarryH3]

Only a single vac line attaches to the MAP sensor.

Are you maybe looking at the EGR solenoid? /forums/images/graemlins/confused.gif It has one line that goes to the TBI and another that goes to the EGR valve. Then there's a 3rd port on it that is just a vacuum release vent. That port comes from the factory with a small piece of foam rubber over it, to filter any air that gets sucked in through it. But the foam falls off after it dries out and gets brittle from the underhood heat. /forums/images/graemlins/frown.gif

The MAP sensor is further back, behind the EGR solenoid.

 

[k20]

I concur w/ harryh3 after lookin at my 87, I couldnt remember what hooked up to what.

 

[CTBlaz45]

OK so then it is supossed to be empty so it is probably an EGR faiure of some sort the symptoms I am having are consitant with the disciption of egr failure. Hope fully that is it. I will replace the EGR and see what happens.

 

[dyeager535]

You can test the EGR if you can reach it. Engine off, reach underneath the "top" of it and push up with your fingers. See if it moves smoothly.

With the valve "compressed", cap off the vacuum port. See if it holds.

If the valve seems sticky, they can typically be cleaned off and will continue to work fine.

 

[CTBlaz45]

Thanks I will try that.

 

[y5mgisi]

on my 90 sub w/ 350 There is a line going from the front of the TBI to (what i think is) the map senseo(The little 1"x3"x1/2" black rectangle thing) then there is a line going to the EGR valve after that. /forums/images/graemlins/thinking.gif