98 Windstar Loss of Power / Hesitation

[Ulsterman]

The van has been running great ever since I replaced the lower intake manifolds, cleaned the EGR ports and replaced the DPFE sensor 15000 miles/three years ago.
Now I have the CEL on with codes P171/4 1131/51 suggesting perhaps a vacuum leak causing the lean condition.
I've looked hard but can't detect a vacuum leak anywhere around the engine.
I did notice however that the IMRC actuators activate with only the slightest blip of the throttle and found this strange.
Anyone have any advice or ideas?

[jayjp200]

Buddy not to discourage you...however I have spent atleast $2000 on changing various parts and have not got any change in situation.

So be wise and spend your dollars.

Jay

[12Ounce]

There's a good chance the one/both actuators have a broken diaphragm = leak. Test them individually for leaking.

[Ulsterman]

Ok 12Ounce I can listen in around the IMRC actuators this evening for any obvious vacuum leak but I'm wondering have you a more scientific test method in mind?
I intend to clean the air intake system including the MAF and IAC although I don't suspect the problem is with either unit. I have noticed some oil has accumulated between the air filter housing and MAF. Will post findings.

[12Ounce]

I use a hand "miti-vac" pump often to supply a vacuum source. But even your lungs will supply enough to see if the diaphragm is leaking. There should be movement on the linkage but no vacuum leak-thru.

Be sure the air filter housing is not your problem ... it could leak a bunch and never be audible. Actually, the diaphragms could be pretty quiet leakers also.

[Ulsterman]

Thanks 12Ounce, I have a mitivac I use for brake bleeding so I'll get that out this evening when I get home. Yesterday I cleaned the air filter, MAF and IAC but didn't get to fire up the engine since the air filter is a K&N reusable type and I set it inside to dry out before re-oiling and reassembly.
I did start it up beforehand but there was no noticable vacuum leak noise from the IMRC actuators. I find it strange that they both activate simultaneously with the slightest touch of the throttle when I'd thought that they should only move at like 3000rpm. It looks to me like they are operating well enough just being commanded at the lower rpm.

[12Ounce]

Somebody can correct me, but I think the design intent is for them to actuate upon engine start-up and re-actuate at higher rpm. I'm not that familiar with your year model.

... So, because of a leak, as soon as you open the throttle, your manifold vacuum is dropping too low to hold them in place. That's my guess, anyways ...

[450HP]

Originally Posted by Ulsterman

cleaned the EGR ports

How did you go about cleaning the EGR ports?

Did you do it yourself or did you have a shop do it?

Scott

[Ulsterman]

SCOTT - if you do a search of this forum you will find many many references on clearing blocked EGR ports. I did the job on my vehicle as I had a cylinder misfire code resulting from a coolant leak which required me to change out the lower intake manifold gaskets. When I got it all apart most of the EGR ports were blocked up. It's really quite straightforward just take your time!
If you were to search under my username you'll see the thread of my post from early 1995 where that most knowledgeable and helpful user '12Ounce' advised me.

[450HP]

All the reading I've been doing has been stating that it's not a DIY type job.

I knew that someone had to have done it before with good results.

I'll take a look... thanks!

Scott

[wiswind]

As far as EGR ports, I have them shown at the beginning of the pictures that the link in my signature takes you to.

On the vaccum actuated IMRC (1996-1998 3.8L), they are OPEN with no vaccum.
When you start the engine, the vaccum pulls them CLOSED.
When I read the post......I also thought that it could be that one of the diaphrams was leaking, causing them to open up with a slight drop in vaccum.
Vaccum is at the max at idle.

It is my guess that there is a vaccum leak in the IMRC actuator vaccum loop.
Check all vaccum lines and connections.....then.....if you have not found the issue......you will need to determine which actuator is failing.
You may be able to do this by unplugging 1 actuator.......and see if the other one stays closed while a helper give the throttle a very slight "blip".

[Ulsterman]

Thanks for the advice 12Ounce and Wiswind. I've been rained off the past couple of evenings (makes me feel homesick for the North of Ireland) but I'll get back to the van tomorrow or Friday and post the progress.

[Ulsterman]

Tonight I reassembled the IAC, MAF and air cleaner unit and tested the IMRC actuators. The van fired up but still the 'choking' type hesitation was evident.
I tried removing the vacuum lines from the IMRC actuators one at a time and finger over the line caused the other actuator to move to close/open so they both check out ok.
Referring to another post I'd read I sprayed carb cleaner progressively over all of the vacuum lines and joints/connections I could find but with no change whatsoever in engine rpm.
So where next guys, anyone have any ideas?

[12Ounce]

Next, eliminate the EGR by removing and capping the control vacuum line to the EGR valve. Give it a test drive.

[tartersauce]

IMRC controlled by Puter.

Open at startup.

Make sure those Connectors are clean and tight!! vac soleniods

EGR if stuck - lean

You have a monitoring Scanner? That may help you pin point things.

Ive replaced a PCM before because it wouldnt control the IMRC..

Oh, if say the EGR is beat, the puter may make up for it with another control to get the engine running better. check the simple things first..

Vac pump hand held one, can test things. But if you dont have one, you can check things quick just by sucking on a hose and see if it holds vaccum. Check all the hoses by pulling them off both sides, finger on one end, vac pump on the other.

What did you clean your MAF with? MAFs arnt cheap either...

Also when was the last time you had looked at the spark plugs? pull them out and remember what cyl they were in. Color etc.. worn?