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Checking the MAP Sensor vacuum line...


gmrulz4u

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On the 2.8 and 3.1L engines, TELL me I don't have to remove the fuckin' plenum in order to check the ENTIRE MAP Sensor vacuum hose for leaks and cracks etc...

 

From my point of view, it looks like the hose runs all the way from the back of the engine, where the MAP is, then UNDER the plenum, and eventually it plugs into the vacuum Tee right near the Fuel Pressure Regulator...

 

Anyone?

 

THANKS A TON!:)

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Well, heres where it goes. From the MAP, it goes into a hole on that thing that holds the 3 cables for the throttle in place, then around the edge of the plenum to the T at the reg. Mine had a small break in it that I couldnt find, so what I did was run a new T from the reg, and ran mine own piece of vacuum line over around the top of the plenum to the MAP, so it doesnt go in the thing for the cables. And, I used normal vacuum line, not that little hard plastic crap. Works great, and makes it easier to take on and off

 

Robby

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Oh, cool! So how the heck did you get the old one out though? Did you just pull on it from the rear/MAP side of the plenum?

 

When you say you used "regular vacuum hose", where did you get it from? Could you be more specific on the type of hose you used?

 

THANKS AGAIN ROBBY!:)

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Well, the old line is still in there, lol! I just by-passed it and never could get it out. And by regular hose, I mean that stuff like coolant hoses, flexible and what not. Are you gettin the right amout of vacuum from the hose that goes to the MAP?? When mine was broke (and it was barely broke) I had like no vacuum.

 

Robby

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Well tomorrow morning I'm picking up a New set of vacuum lines and the plastic peice that goes into the throttle body or whatever...I ordered it from GM today...it's $33 CDN, which isn't TOO bad...

 

On Sunday, I went to pull the line off that goes from the TB into the Fuel Pressure Regulator/MAP Sensor "tee" to fix 2 cracks that it had in it, but then the whole thing just broke in half!! So I just temporarily taped them back together...

 

If my MAP voltage stays high, like it has been, after I replace this line, I'm going to want to "check out" the line that goes from the "tee" to the MAP Sensor itself...

 

I measured 18" of hg(vacuum) at the connection for the FPR/MAP vacuum line, which translates to 1.5 volts from the MAP(according to GM), but my MAP was reading 1.8 volts(lower than actual vacuum) instead, which makes me think the line going to the MAP must have a crack in it or something!??

 

I'll do more investigating tomorrow though:)

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Yeah, you're probably right.

 

So is the MAP Sensor just held into place by that metal clip? It's just a simple thing to remove, right?

 

Also, I don't quite understand what you mean when you say "run a new T from the reg, and ran mine own piece of vacuum line over around the top of the plenum to the MAP, so it doesnt go in the thing for the cables."?? How did you run a NEW T from the reg?? I just can't picture what you're talking about...

 

:)

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Yeah, that MAP is just held by the clip.

 

Okay, the diameter of the line that attaches to the FPR Tee is not the same as the diameter of the line that fits on the nipple of the MAP sensor. And, the new piece of vacuum line I ran, was the diameter of the nipple on the MAP. So, the new Tee I had to run was one that was the size of the line coming from the MAP one end, and on the other it was the size of the line at the FPR.

 

For the routing of it, the new line, since it is long and more flexible than the stock piece, I simply ran it over the corner of the plenum and around to the MAP, and didnt put it through its stock routing. Hope that helps

 

Robby

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Yeah I think I got it? I just don't understand WHERE you put the NEW T? Did you get rid of the OLD T as well?? It looks like it would be hard to work with because it's pretty much UNDER the plenum itself...

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Okay, I just went out and checked on how I had mine set up, cuz I couldnt remember completely. Heres how it goes. I have the stock line from the TB to the stock tee and the stock tee attaches to the FPR. Then (heres where I told ya wrong), from the outlet on the stock Tee for the MAP line, I have a thing that attaches the smaller dia. stock line to the bigger dia. line I have for the new MAP line, then just ran the new MAP line over the part of the plenum close to where TB attaches. Maybe that makes more sense

 

Robby

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OK, now I get it, that makes more sense!:)

 

So you didn't really use a SECOND T, you just used the stock T along with a connector for the two different diameters of MAP hose/line...right?

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Yeah, thats right. I couldnt remember exactly how I did it, thats why it was hard for me to convey. I guess going out and checking it was the best

 

Robby

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