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vacuum diagram


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Hey Pete,

If there was, mine's missing. I crossed something up during re-assembly. I had removed the thermostatic air cleaner stuff, and put a screw in the vacuum line a couple of years ago, and no problems. So I made some bonehead vacuum line swap and now the truck is racing like you can't believe.

 

Tom

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Thanks for trying, guys. I have the first book, I just can't make heads or tails of the diagram when I look under my hood.

 

There are FIVE ports in question:

two on the side of the throttle body, facing the valve cover. I think one goes to the MAP and one to the rear grommet on the valve cover.

 

There is an L valve on top of the intake manifold, and I'm not sure where the lines that draw vacuum from these run.

 

Finally, there are two ports on the backside of the air cleaner. The bottom one is just a plug, in otherwords it's not functional. I'm not sure what line goes to the top one.

 

Just so I'm not blind to what I might have done wrong here, if it's not the vacuum setup (and believe me, I've tried a few different ways), what else would cause my engine to tach at about 5 grand and stay there on startup? The throttle is closed, I even disco'd the IAC motor.

What have I done???? :mad:

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  • 2 weeks later...

That's ok, I think I have it figured.

Someone over on 4bangerjp had a more detailed diagram than the one above, and that clicked it for me!

 

This project has been so bad. I still haven't gotten the EGR tube back on because you have to fab it, and I'm a bad steel fabber, and a worse TUBE fabber. There's weld everywhere, and the pipe looks like a pretzel. Bought another MJ just to drive around in while this project is laid up!! I've truly lost it..

 

 

:nuts:

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Ok,

So I finally fabbed the steel EGR line and the engine is still off to the races. I have all the vacuum lines hooked up as in the diagram, but it's really taching like wild (no tach so no idea). I put on an exhaust header, so I had all the lines off, the intake, and put it all back carefully. WTF would make it idle like this? Some people thought the EGR tube being off, but now it's on, and I have an open header...could the engine be reading this as a lean condition and racing? I am stumped...

 

:hateputers:

 

Tom

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Tube bending isn't bad. Just take your time. Plan ahead(read: buy extra)

 

I always try to think of it as the same as bending DOM stuff. You would measure DOM tubing 4 or 5 times because of not wanting to waste any. Use the same care with the small cheap stuff.

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I had the gasket leak and mine would do this alot it would also backfire when i was just driving around. Spray around it with carb cleaner or starter fluid and get it all around the cracks to see if it revs or dies down if it does where your spraying is the bad spot.

 

Cole

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I had the gasket leak and mine would do this alot it would also backfire when i was just driving around. Spray around it with carb cleaner or starter fluid and get it all around the cracks to see if it revs or dies down if it does where your spraying is the bad spot.

 

Cole

 

I'd be really surpsied if my new semi-metallic combo (intake exhaust) gasket was leaking.

 

:eek:

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I'm still suspecting a major vaccuum leak somewhere on the intake, but I snapped a couple pics of the vac lines on my 2.5 for you to reference.

 

On the passenger side of the TB, there are 2 vac ports. The lower one goes direct to the back of the VC, and the upper one goes thru the plastic vac tree to the MAP.

 

On the top of the TB cover, driverside rear, there are 2 vac ports. The lower one goes to a vac port on the intake manifold, and the upper snakes around the back of the TC, thru the vac tree, to the EGR solenoid.

 

Hope that helps Tom. If you need any other pics lemme know...I've got the dig cam and the MJ here with me at work. I can post 'em up in a jiffy (the boss is off today :D )

Jeff

 

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On the passenger side of the TB, there are 2 vac ports. The lower one goes direct to the back of the VC, and the upper one goes thru the plastic vac tree to the MAP.

 

On the top of the TB cover, driverside rear, there are 2 vac ports. The lower one goes to a vac port on the intake manifold, and the upper snakes around the back of the TC, thru the vac tree, to the EGR solenoid.

 

Hey Jeff - Thanks. I'm with you on the TB ports. Those 2 vac ports, however, on the back of the TB cover, I have screwed up. The upper port is a dummy port, just a plug, so it's weird it goes to the EGR solenoid. Which part of the EGR solenoid does the other end go to? And I guess the vacuum line to the EGR valve goes to the other part of the EGR solenoid.

 

Also, you mentioned the vac port on the intake manifold -- mine's L shaped, so it has 2 ports, really. Where does the other line from it go? Thanks a ton, Jeff!

 

Tom

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I suck at the interweb, but lookie at this

 

(almost as good as an FSM diagram :D )

 

*correction - the upper vac port on the TB housing goes thru the tree, back to the firewall, then over and down the driver side fender to the airbox (not to the EGR solenoid). The lower vac port goes to the manifold port.

 

The larger vac line off the manifold port goes thru the tree over to the back side of the EGR solenoid

 

The line off the EGR goes to the front side of the EGR solenoid

 

Jeff

 

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