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Don Knight
Don Knight, ASE Certified Technician
Category: Mercury
Satisfied Customers: 1736
Experience:  40 Plus years on all makes and models
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Mercury Villager: I have a 1999 Mercury Villager that has a

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I have a 1999 Mercury Villager that has a vacuum hose connector with no hose attached and there is none in sight. This is located Left of the EGR on the back side of the intake I jacked the van up high enough to get eyes on the back of the motor and can feel the male receptacle but I don't know what it connects to. Is there a vacuum routing diagram of the back of the motor (closest to the firewall that would tell me where this hose connects to?
My name is XXXXX XXXXX I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

Here is a vacuum diagram I have located for your vehicle here,this should also be on a label on the under side of the engine hood.Let me know if this helps with what you are looking for here.


Thanks Pete
Customer: replied 4 years ago.


This diagram doesn't help. I need a diagram of the back side just to the Left side of the EBT / EGR (as you look at this diagram). There is a 3/8 - 1/2 inch hose that is on the intake manifold and just to the left of that hose and down toward the floor there is a male vacuum hose receptacle that I need to know where the hose goes. Somehow this connection got knocked off and there is no visible sight of it anywhere. Please provide a detailed diagram of the hoses on the back side of the intake manifold so I can know where to connect this missing hose.


Does this picture below describe what you are looking for as this is the EVAP emissions vacuum hose?


Let me know,thanks Pete
Customer: replied 4 years ago.

No. This is a diagram to the right side of the throttle body the placement I need to see is to the very back (firewall side) and to the Left side of the EGR / EBT as you face the firewall from the front number there is a hose visible between the intake manifold and the top of the cavity (just below the windshield. The diagram I need is below (toward the floor) and slightly to the left of that larger hose.

O.k.,unfortunately this is all of the vacuum hose info I have on this model here.Someone else may have more info on this to help more here.

I will opt out and put this question back on the list to see if others can help more.Don't reply to my last post here unless it is a last resort as it will keep the question locked to me.I hope you can get this resolved with ease.

Thanks Pete
Customer: replied 4 years ago.

Yes, please post so someone else may be able to help. Thanks for using the resources that you have available.



Your welcome.I have opted out for you on this.I hope you can get this resolved with ease.Don't reply to my last post here as it will leave the question locked to me.

Thanks Pete

I’m a moderator for this topic. It seems the professional has left this conversation. This happens occasionally, and it's usually because the professional thinks that someone else might be a better match for your question. I've been working hard to find a new professional to assist you right away, but sometimes finding the right professional can take a little longer than expected.

I wonder whether you're OK with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Thank you!
Customer: replied 4 years ago.

I am willing to wait... however after checking with the salvage yard I am convinced that what I thought was an open male vacuum receptacle is not a vacuum port!


The problem I am having is this - After changing my timing belt and a number of pulley bearings etc. the engine fires up immediately and runs fine until the fast idle kicks out. The Autozone handheld diagnostic reveals that there is a multiple random misfires. The van runs great on the highway and performs well. I suspect the IAC valve may be gummed up a bit causing the rough idle - though there is no code reading of a malfunction of this item.


I can't seem to locate the IAC valve... the placement of this valve apparently is buried under the Intake Manifold (firewall side). I have placed a light back there and can't see the valve or the solenoid that accompanies this part. I'm wondering if I have to take the intake manifold off to even see the IAC valve.


Please advise on the possibility of the IAC valve as a likely cause of the rough idle as well as the location of the IAC. According to my manuel it is to the right side (Right as you sit in the Driver's seat) of the ERG/ EBT (though I can't seem to see it.

Thank you for your continued patience. We will continue the search for a professional for you.
Thank you for your patience, your business is very important to us, we are waiting on the Professional with the right expertise to come online. Feel free to let us know if you would like us to continue searching for a Professional or if you would like us to close your question. Thank you for your understanding!
Customer: replied 4 years ago.

Yes, keep looking - I need to get my van back on the road! Surely you have someone who works on Mercury / Villagers?

Good morning.The idle air control valve mounts on the upper intake manifold.It has two blots that hold it to the manifold and on the back of the valve is the electrical connector.It is forward of the throttle body about 3 inches.The book time to replace the valve is .8 of an hour so it sould not take you to long to replace it.If you are not sure of what it looks like just purchase a new one before you are ready to replace the old one,that way you will know exactly what the valve looks like.Please let me know if you need and more assistance,Don
Customer: replied 4 years ago.

When you say the IAC is "on the upper intake manifold" do you mean on top of the manifold? Or, is it underneath the manifold?


I have a picture of the IAC printed from AutoZone it appears to have 4 bolt holes holding it down - so I am confused.


You said it is about 3" forward of the Throttle body; I'm assuming that is drivers seat Left - That is where the EGR valve is... is it behind the EGR? or further beyond the EGR? A picture or diagram would really be helpful.



It is on the left side of the manifold(drivers side) and it only has two bolts not four,Like I said the r&r time is under one hour so you really dont need to remove anything other then the valve itself.Sorry I dont have any pictures.
Don Knight, ASE Certified Technician
Category: Mercury
Satisfied Customers: 1736
Experience: 40 Plus years on all makes and models
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Customer: replied 4 years ago.

I still have not been able to locate the IAC valve. I have found 2 different designs on line. While they are similar they are different. Both are listed as IAC valve for a 1999 Mercury Villager. I have found nothing fitting this design on the back of the intake manifold. Again, is the "2 bolt IAC valve visible on the top of the manifold or is it buried behind the manifold or underneath the "overhang"?

It is not under anything,it is on the side.All the iac valves that I have ever change by Ford only have two bolts.
Customer: replied 4 years ago.

Ok, I've found the AIC valve. It sits right out in plain sight. I have removed it and cleaned the chambers but still have a rough idle. By the way FYI there are 4 machine screws (phillips heads on each) holding the top plate to the throttle body on this model. This one does not match either of the two types I mentioned above. Apparently the Haynes manual that I have show pictures of a Quest which located their IAC on the passengers side just about under the windshield wiper base. It also has an idle adjuster screw you can reach from the top of the motor.


That aside. I have purchased a IAC valve from a salvage yard and I will install it with a different throttle body and a different EGR - all came off a 2000 which is compatible with my '99. I plan on cleaning each of these items really well and replace my parts with them. I'll try this next week.


If you have any other suggestions regarding what to look for next to solve this rough idle problem please share your ideas!


Given the year of your van I would check the throttle bore and make sure that it is clean, especially where the throttle plate rest.That is usually the most common cause for a rough idle.