Confused about intake manifold.

On the companion site there are several photos posted that someone posted while replacing the isolator bolts. I was looking at them to try and figure out how the IMDR (or whatever they are called) works and where the longer runners are.

There are two photos of what I thought were the same things until I looked a bit closer. They are:

"Cleanedup.jpg" and
"100_0107.JPG"

These must be from different years. Does anyone know which is which?

I think "Cleanedup" is from 99.... but I am unsure. It also is not clear what the IMDR butterflies actually do when they open or close.

If anyone knows please do tell.

You are asking a good question. I don't know.

But the Haynes manual that I have applies to 1995-2000 models. It shows the Intake Manifold Runner Controls (complete with the individual jets) on all 3.8's from '96 on. At least, that's what I think it says.

I think the whole IMRC thing is a bunch of crap, I think the design rationale goes something like this:
...Some engine designer had a concern about the distance there is for the air to travel between the throttle plate and the "other" end of the engine, cyls #1 and #4.... at low rpm..."there might be a lag time" he percieved. So he divided the manifold airstream into halves and put in butterfly valves... so that at relative low rpms (i.e., low manifold air flow) the "time" between the throttle plate and the combustion chamber is reduced (when the butterflys are closed...speeding the air up)! At higher rpm (when the manifold air flow is much higher... no "lag time" problem) the butterflys open allowing full breathing.

Wow! If he had just had another cup of coffee that morning! I believe there are other (PCM program) ways to compensate for the slow air at low rpm.

There must be something I'm missing, I know. Will someone please share it with me!...????

I can clear up the pictures question. The "Cleanedup.jpg" was from a set of pictures taken by user Thor20 from the cartrackers site when he did the TSB repairs, he sent them to me and I posted them for him. I think he has a 99 but definitely a 99+ if not a 99.

http://groups.msn.com/FordWindstar/shoebox.msnw?action=ShowPhoto&PhotoID=22

The other picture was posted by Tarheel4ever1 who has a 97 Windstar I believe.

http://groups.msn.com/FordWindstar/shoebox.msnw?action=ShowPhoto&PhotoID=27

Thanks guys.

I think I can add a little too. As far as I know when an intake has long runners (distance to travel to the cylinder) the engine develops better torque than when it has short runners. This is desireable at low RPMs. However at high RPM the long runners offer intake resistance and thus the airflow becomes the bottleneck that prevents the engine from developing HP which normally occurs at higher engine speeds. Normally an engine is designed with compromise and thus they develop satisfactory torque and hp but does not accel in either.

I always beleived the intake runners offered a different path for the airflow at different RPMS to get the best of both worlds. For example if the runners are closed at low RPM on can assum that there is a long run and when they open (at 3000 RPM or so) a secondary short path is introduced. The air would take the path of least resistance and the long runs would not contribute as much at this point.

When I was looking at the photos I could not verify this. I suppose I would need to see the bottom of the lower intake. A co-workert of mine has a 2.5 Contour and his intake clearly shows different paths available for the incoming air via control from the IMRC.

Of course I may be incorrect in all of my thinking.

DRW
I think I understand what you are saying about different "lengths" of intake barrels for different engine rpms...I remember (in distant time) studying how dia X length of pipes, with gas flowing through, results in "standing waves"... sometimes referred to as "tuning". The resistance to a flowing gas can sometimes be REDUCED by LENGTHENING a pipe a bit more.
But I don't see anything different about the intake "lengths" on the Winnie engine ... it only looks like changing the cross sectional area of the intake to me.
??

12Ounce aka "old and confused".

If I were a betting man I would put my money on you being correct and me being incorrect.

Thanks for the thoughts.

They changed the intake manifold in '99.
I have several pics at

http://community.webshots.com/album/201931518cScpNK

Idea is to increase air into the cylinder for a hard acceleration above about 2900rpms....and have better fuel economy otherwise. Kinda similar to the old "4 barrel" carberators where the extra 2 barrels open up under hard acceleration.

These pictures are from my '96.

I can clear up the pictures question. The "Cleanedup.jpg" was from a set of pictures taken by user Thor20 from the cartrackers site when he did the TSB repairs, he sent them to me and I posted them for him. I think he has a 99 but definitely a 99+ if not a 99.

http://groups.msn.com/FordWindstar/shoebox.msnw?action=ShowPhoto&PhotoID=22

The other picture was posted by Tarheel4ever1 who has a 97 Windstar I believe.

http://groups.msn.com/FordWindstar/shoebox.msnw?action=ShowPhoto&PhotoID=27


That is correct lewisnc100. I didn't have my EGR ports cleaned out yet. I didn't have any carb cleaner to get rid of the carb build-up in the lower manifold. I recently have the 1537 & 1538 codes. My rear plenum is faulty after some troubleshooting. I had a rough idle but I sprayed the linkage with some lube. Hopefully the idle stays up. Will report back when I find out more.