99 Windstar Lean

i have a 99 windstar and i have the 171 and 174 trouble codes. my mechanic told me that is was the flapper valves in the intake but ive read it could be the isolator bolts. which is more common/likely?

It's probably your isolator bolts/left bank rocker cover. Read the info on the problem code 171/174 (the top post stickied at the top of the forum).

By the way, if I'm thinking the same thing that your mech is talking about, to het to the intake flapper, you have to remove the upper intake manifold....and you'll be staring at the isolator bolts.

HTH

are those valves supposed to move if i blip the throttle? because i just checked and they dont. the linkage and bushing look ok. ill spray it with wd-40 or similar tomorrow to see if there is a leak.

1999 is one that is covered in the sticky post at the top of the windstar room.
The '99 will need the new front valve cover....or modification to the oil baffel over the PCV hole.
If the front valve cover has already been replaced, it will be silver instead of black.

The "Flapper valves" are the IMR (Intake Manifold Runner) or IMRC......Intake Manifold Runner Control.
The "flapper" would more correctly be called IMR or butterflies....they are kind of like the butterflies in a carborator......or the big one in the throttle body.

As far as control, the 1999 uses an electrical actuator.....so the posts about vaccum leaks....diaphram leaking ....do not apply as the vaccum actuated ones are on the 1996 through 1998 years ONLY.

HOWEVER, there are nylon CLIPS on the IMRC that are noted or breaking or falling off.....
These clips connect the linkage between the actuators (which move the "flappers" inside the lower intake manifold) and the shaft that the flappers are mounted on.
So the actuator would move....but the butterflies would not.
This is mentioned in a FORD TSB relative to pinging.

Another thing that can happen with the IMRC system is that the shaft can wear in the lower intake manifold.....where it passes through the sides......and cause a vaccum leak.
The solution to this is a new lower intake manifold unit.

I would make sure that the IMRC system is working.....shafts are connected to the actuator.....and moving.
Also verify that the TSB mentioned in the sticky at the top of the windstar room has been done.
There is an excellent site here
http://leckemby.net/windstar/windstar01.html
that is mentioned in this post.....which was put together by one of the forum members.

If you mean the flapper/butterfly left of the fresh air rubber tube (left of the air filter), that's the throttle body.

There's a smaller set of flappers/butterflies in the lower intake manifold.

In this link, the last pic, you can get a glimpse of them in the intake passage (the top 3 ones), though it's kinda hard to see.

http://leckemby.net/windstar/windstar01.html

By the way, when wd40 dries, it leaves a tacky brownish film. Personally, I don't use wd40 around my cars.

As far at the question if they should move when you punch the accellerator.....no.
They are supposed to open at a given RPM.....about 2900 for my '96....but I read someplace that they may have used a different RPM for different years.
The main thing is......if the actuator does not move....then you will get a CEL (Check Engine Light) with a code(s) indicating a problem with the IMRC.
If you do not have a code....then the actuator is moving correctly.
HOWEVER.....if they nylon clips are broken.....then the runners (butterflies in the lower intake manifold) are not running with the actuator......so the PCM thinks that they are moving....but they are not.
One thing that can happen is 1 side moves...and the other side does not......which results in a unballanced situation with the motor....because 1 bank of 3 cylinders is getting more air than the other bank.

What the IMR (Intake Manifold Runner) system is trying to do is to have an extra port for EACH cylinder.
Under normal conditions......this extra port is closed off while the motor is running......by closing the butterflies.
Under full accelleration......the IMRC opens these butterflies to give each cylinder MORE air......which gives you a boost of power...when you need it.
But you get better fuel economy when you do not need the extra air.
This is kind of like a modern version of a 4 barrel carborator....when you romp on it.....the 2 extra barrels used to open up to give you more power.

But in short....I am not big on reving the motor to see if the IMRC opens up at high RPM.
Just make sure that the linkage between the actuator(s) and the shafts that go through the lower intake manifold are intact.
If the actuator(s) do not move correctly......you will get a CEL to tell you.

I am not up on the electrical actuators.
My '96 has the vaccum ones........which do the same thing...but look different........

i am quite familiar with butterfly valves because i have a motorcycle with four carburetors. it is indeed the IMR system not the throttle body that i am talking about. the bushings are intact. i sprayed the rubber bushings with PB Blaster because it says it will restore rubber for a short time. if it comes down to me needing a new intake manifold, where can i get one besides the stealership?