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Thread: Vacuum Hose Question/EGR spacer questions

  1. #1

    Default Vacuum Hose Question/EGR spacer questions

    So, I'll get flack for this, but what are the repercussions of removing the EGR spacer on an 87 Grand Marquis, like, entirely. What does it do, and why did Ford put it there in the first place?

    Much more importantly is this... in the center of the intake, or more correctly somewhat under the upper intake, there is a vacuum hose, mine had rotted off and I have it roadside rigged back on there. Obviously this is because the vacuum leak made my idle high and stupid. I didn't even know it was there until I investigated, pain to do with a hose that doesn't fit right and heat shrink to make it "fit". /I no longer have a vacuum leak. But, onto the question part.
    What does the aforementioned vacuum hose do, and can I cap it off instead? Anybody have a vacuum diagram for these cars?

  2. #2
    Carthago delenda est Lutrova's Avatar
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    Dec 2019
    Fort Irwin, CA


    I think Ford put it there to have a place to recirculate exhaust gases back into the engine. Don't know for sure what would happen, but I can think of a couple issues. 1) The cables running from the throttle body to the gas pedal, trans, and cruise control might not line up right. 2) You might not have enough clearance between the IAC valve and the wire harnesses that (2a) were formerly mounted on the back of the EGR spacer. 3) Exhaust gases will now be hitting the back of the throttle body, which may or may not be a problem.

    Not sure which vacuum hose you had come loose, but depending on which one it was it could be fairly important. There are two vacuum connections off the front of the underside of the manifold and three off the back. The front two go to the charcoal canister and the PCV valve. The back three go to the fuel pressure regulator, MAP sensor, and a vacuum tree that serves a whole bunch of different things.

    Click image for larger version. 

Name:	89 Vacuum Diagram.jpg 
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    The filename for that image said 89, but I believe an 87 should be similar or identical.

  3. #3
    I'm an air-conditioned gypsy gadget73's Avatar
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    Jan 2005


    If you remove it, you have nowhere for the throttle cable bracket to attach. Downside is you can't drive the car above idle speed. Upside is you won't have to buy fuel very often.

    Just put it back on there. When working, EGR reduces emissions and improves fuel economy. It also does not cost any power since it shuts off under heavy throttle. The only somewhat negative is that it slightly increases the intake air temperature, but frankly with a metal intake its going to heat soak so much that its not significant.

    and yeah depends what hose you speak of, but there aren't really any "extras". Back side barely accessible I'm guessing is the MAP sensor line, which is how the ECM monitors engine load. Pull the intake and replace both of the ones that go far underneath.

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    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

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  4. #4
    Member tbear853's Avatar
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    Jan 2021
    Virginia but I started life in Texas


    We plugged them back in the day, one passage to intake, other is to exhaust. EGR connected the two with a vacuum diaphragm operated gate controlling the flow. They were made of aluminum and often corroded and lead to leaks on the exhaust side, stainless steel and snips made a nice separator plate for between adapter and intake manifold.
    No ... I'm not arguing with you ... I'm just explaining why I'm right ...

    Now go ... and whatever you do ... have a safe trip!

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