Winstar Vacuum Hiss / IMRC Question

Hello Everyone,

I have been working on my 2001 Windstar for months. I've been getting various engine codes mainly 171 and 174 (lean banks). Also has a cracked coil that was throwing a misfire code when it got wet and had me barking up the wrong tree for a while. Here is what I have done so far:

1) Replaced MAF (probably didn't need to...was the coil pack problem).
2) Replaced vacuum line that goes from the lower plenum to a vacuum manifold. It is a 3/8 rubber hose that was in fairly bad shape and connected to the lower plenum just after the fuel intake.
3) Replaced plenum (upper) gasket, isolator bolts with new green ones, and lower port seals (6 of them). I also cleaned the EGR ports and butterflies while I was down there. It was terrible...I've not seen people with pictures that were worse than mine. Three of the ports were completely blocked! I had everything perfectly clean when I did the re installation.
4) Replaced the four IMRC plastic grommets that connect to the motor to open the butterflies. The front rod was completely disconnected and the back was barely hanging on.
5) Replaced the PVC valve and rubber grommet on the value cover. It was falling out because it was so loose. I think I had the updated value cover and I did not see a hole like everyone describes.

I have not seen the 171 and 174 yet...but I haven't even pulled it out of my garage yet. My concern is what sounds like a vacuum leak that sounds like it is coming from under the intake manifold. If I pump the gas at idle I can hear what sounds like a strong suction sound in the manifold. It was making this sound before I replaced the isolator bolts but I was hoping it would go away after the repair. Another thing that concerns me is when I turn off the van I can hear a strong sucking noise from what sounds like inside of the manifold. I have listened all over the engine and I don't think it's a line outside of there. After the van is off it will make the sucking sound for about 3 seconds. I can also hear the PCV value rattling towards the end of the sound...as if the vacuum pressure if slowly leaving the van (but the sucking sound is not coming from there).

Is this normal? I've never noticed the sound before until I had problems with the coil pack and started really paying attention to the van. I've put a vacuum gauge on the lower plenum and the vacuum pressure didn't seem to move...just stayed at 19 the whole time. Does anyone know what may be causing this sound?

Also...how can I check if my IMRC motor is working. I read that at 3000 RPM it is suppose to open the butterflies but when I try to watch it at idle I don't see the rods move. They seem to stay close the entire time no matter how fast I run the engine.

I saw no cracks in the upper and lower intakes and I'm sure I had a strong seal when I put everything back together. It's odd that the sound is there both before and after I did all of the repairs. The van seems to run fine both at low and high RPMs. I can detect no rough idle or lack of power on the road.

Thank you for any help you can provide. Hopefully I am just over analyzing the sound...

I won't comment on the vacuum sound as there are several true experts around this site. What I will say is that I have a thread going '98 Windstar loss of Power/Hesitation' which has some good information on the IMRC's i.e when they move when they don't.
Good luck you have a much newer van and surely Ford made some improvements.

Thanks...I checked it out and it had a lot of good info. I am confident that my IMRC motor is not working but I don't get the van past 3000 RPM very often anyway...so I'll look at that a different time.

Quick update. My check engine light still has not came back on but I'm still supecting a vacuum leak due to the sound being made when I turn off the van. Can anyone with a 2000 or newer van try to confirm if they hear a vacuum sucking sound for a few seconds after turning off their Windstar? If the hood is closed you may have to listen closely with the driver door open (with the hood open it is very obvious).

Went to breakfast with my dad and I popped the hood and let him listen. At first he didn't think it made the sound...but when I told him to listen closer he heard it and said it sounded like it was coming from inside of the upper manifold. We just can't confirm if this is normal. I would suspect that the vacuum pressure would be released when the van is turned off...just not sure how this happens or where the pressure is usually released.

Does anyone know how this works???

I won't comment on the vacuum sound as there are several true experts around this site. What I will say is that I have a thread going '98 Windstar loss of Power/Hesitation' which has some good information on the IMRC's i.e when they move when they don't.
Good luck you have a much newer van and surely Ford made some improvements.

Actually the sequence of the '99 elect actuator is different from the '98, and earlier, pneumatic actuators. The elect doesn't move at all at engine start-up ... but does actuate at hi rpm if the engine is loaded.

One way to prove that its moving is to put a daub of heavy grease in the path of the linkage ... then take it for a brisk ride and acceleration. You will find the grease "disturbed" if the actuator worked.

Get a three foot piece or garden hose, etc, to listen around to pinpoint the source of your hissing. Your pvc rattle and hissing simultaneously somehow seem connected, or just because both are loosing vacuum simultaneously, so nothing. You can also use starting or carburator fluid to spray around everything in hopes your vac leak will suck it up and change the engine speed and sound. I have never heard a pvc rattle when the engine is turned off, so I have my suspiciouns. There have been issues with aftermarket pvcs not fitting and only remedied with Ford's.

The best way to tell if your IMRC is working is if your vehicle is driveable is to go find a steep hill. Start driving up and at about 3000 RPM, you will feel like someone has bumped your vehicle from behind. If one of the connecting rods has disconnected and only half of the butterflys are opening, then the bump will be there but not as noticable.

The best way to tell if your IMRC is working is if your vehicle is driveable is to go find a steep hill. Start driving up and at about 3000 RPM, you will feel like someone has bumped your vehicle from behind. If one of the connecting rods has disconnected and only half of the butterflys are opening, then the bump will be there but not as noticable.
The Electric controlled IMRC will open if you goose the throttle in park. They are quick, so keep your eye on the front one. At idle, Snap the throttle more then the Half point, They should start opening and they are fast too.

The hissing noise when turning off, Yup, mine does the same thing.. Since the INtake mana is so big, When you turn the engine off, that vaccum has to match the outside air pressure and thats the noise you hear. Air pressure matching "getting sucked into the intake" the air pressure outside. It takes 3 4 seconds because of its gotta get around the buttlerfly.
You also hear it more, because the intake hose is mounted closest to the drivers side window..

I have a 2001 and I hear the same hiss when I shutoff the engine. For me it sounds like it is coming from the passenger side. I only hear it when I shut off the engine. It takes a few seconds to go quite and I figured, as mentioned, it was the negative pressure equalizing to atmospheric.

I can't see the IMRC moving when sitting in park with the engine reved up over 3000 RPM. I think I might try one of the ideas of putting something in the path of the rod to see if it gets disturbed. The van seems to run fine wihtout hesitation, but I just can't confirm if the rod is moving or not...

If the actuator is NOT working, you should get a CEL light with a code stored for it.
I prefer 12ounce's suggestion of a dab of grease over the racing the engine idea.

What folks have posted as being a problem with the 1999 and newer IMRC is the nylon bushings / clips breaking / falling off, so that the IMRC actuator is no longer connected to the actual IMR shafts that go through the lower intake manifold.

It is for certain that you are NOT getting a vaccum hiss from the IMRC actuator on a 1999 and newer windstar....as they are ALL electrically driven.
HOWEVER, there have been several posts of the lower intake manifold wearing at the points that the IMR shaft passes through it......causing a vaccum leak.
The fix for that is replacement of the lower intake manifold.
From what you have described in this post.....that does NOT sound like an issue in your case.
If you started to get the lean codes again....then one would add it to the list of things to check......note that I say LIST......as there are other.....cheaper and easier things to look at FIRST.

I have a 2001 and I hear the same hiss when I shutoff the engine. For me it sounds like it is coming from the passenger side. I only hear it when I shut off the engine. It takes a few seconds to go quite and I figured, as mentioned, it was the negative pressure equalizing to atmospheric.

I can't see the IMRC moving when sitting in park with the engine reved up over 3000 RPM. I think I might try one of the ideas of putting something in the path of the rod to see if it gets disturbed. The van seems to run fine wihtout hesitation, but I just can't confirm if the rod is moving or not...

Are you kidding? Grab the throttle, right wear the cable connects to the butterfly and goose it under the hood.. Not from inside with the pedal! You can look right at the IMRC linkages and reach the throttle right under the hood.. Of coarse you cant see it from the drivers seat...

Are you kidding? Grab the throttle, right wear the cable connects to the butterfly and goose it under the hood.. Not from inside with the pedal! You can look right at the IMRC linkages and reach the throttle right under the hood.. Of coarse you cant see it from the drivers seat...

If you want a video of them opening, I can make one.. If you hold it at 3k rpms they wont open, You need to go from Idle to More then Half throttle almost like punching it.. They will open up..

I have tried reving her up both ways; 1) my wife stepped on the pedal and held at 3k and 2) I reved the throttle and watched. I didn't know you had to punch it. I don't have the lean codes since I did the grommet replacement on the isolator bolts. I will try again by reving it up fast or with the dab of grease.

Thanks