96 Windstar engine miss under load

[_pete_]

Hi, I hope someone here can help me out.
My 96 Windstar is driving me crazy. I've had the PO171/PO174 CEL problem for a while. I replaced the O2 sensors (did nothing) and since the car ran fine, I just ignored the CEL.
All was fine until last week driving from Tennessee to Ohio. I make this trip often and have had no problems until now. I could feel the engine missing and surging when under load. It does it whether hot or cold and it's very pronounced during acceleration from a stop. If you floor the gas and kickdown the trans it runs fine. It also seems to be ok during steady state cruising.

I've scoured the web for days now and found the isolator bolt fix but it doesn't apply to my '96.
I changed the coil pack, plugs, and wires and all that did was cost me $100. No change at all with the problem.
I cleaned the MAF, verified that the IMRC's are working, and checked for vaccuum leaks (found none).
I also tried plugging the vac line to the EGR and test drove it. No change.

The next step would be to pull the intake manifold and clean the EGR ports but I am getting very tired of working on this thing with no results.

It's my only car and I don't have money to keep throwing at it in hopes of finding the fix.

Any and all suggestions will be welcomed.

[wiswind]

If disabling the EGR did not change the symptom, then that would indicate that the EGR ports are not the issue.
I would do 2 things.
First, I would check for a vaccum leak.....start with the PCV line from the top of the upper intake manifold......Mine developed a crack on the inside of the elbow that connect to the top of the upper intake manifold.
Follow that line all the way back to the PCV valve....and verify that it has not developed any leaks, or that none of the several lines that connect to it have become disconnected.
Check to verify that the line that goes from the breather, on the FRONT valve cover, is intact at both ends.
This line connects to the back side of the flex hose that goes from the air filter/MAF to the throttle body.

Second, I would get 2 cans of Berryman's B-12 Chemtool, in the metal can, and add 1 can to each of the next 2 tanks of gasoline.

It would also be worth reading the codes again, if you have not done so recently.
You can get your codes read for free at AutoZone and Advance Auto parts....as well as many other auto part stores.
MAKE SURE that you get the actual numeric code.
This is just in case something else has cropped up.

As you don't mention a misfire code, this is why I suspect the 2 things that I mentioned.

[_pete_]

Originally Posted by wiswind

If disabling the EGR did not change the symptom, then that would indicate that the EGR ports are not the issue.
I would do 2 things.
First, I would check for a vaccum leak.....start with the PCV line from the top of the upper intake manifold......Mine developed a crack on the inside of the elbow that connect to the top of the upper intake manifold.
Follow that line all the way back to the PCV valve....and verify that it has not developed any leaks, or that none of the several lines that connect to it have become disconnected.
Check to verify that the line that goes from the breather, on the FRONT valve cover, is intact at both ends.
This line connects to the back side of the flex hose that goes from the air filter/MAF to the throttle body.

Second, I would get 2 cans of Berryman's B-12 Chemtool, in the metal can, and add 1 can to each of the next 2 tanks of gasoline.

It would also be worth reading the codes again, if you have not done so recently.
You can get your codes read for free at AutoZone and Advance Auto parts....as well as many other auto part stores.
MAKE SURE that you get the actual numeric code.
This is just in case something else has cropped up.

As you don't mention a misfire code, this is why I suspect the 2 things that I mentioned.

Well first off, the elbow hose on top of the maniflod is new. The hose from the front breather looks fine and is connected to the accordion tube at the throttle body. I checked all the vac lines when I replaced the plugs & coil yesterday and rechecked them all today. None seem to be in bad shape, disconnected or leaking.
The CEL has been showing codes PO171/174 for over a year now. When this problem started, I had Autozone check the codes again to see if there was a new one. There wasn't. It still only shows 171/174. They reset the CEL at that point so the light is off for now.

2 tanks of gas may be a problem because the van is barely driveable.

This thing has me stumped.

[_pete_]

http://www.automotiveforums.com/vbul...Windstar+surge

The author of this thread had the exact same issue but never posted a solution.


I read another thread where the issue was the cam sensor was installed incorrectly.

Can that sensor timing change? Ny car was fine for years and this started during a long trip, The sensor has never been touched. Could it still be the iproblem?

[wiswind]

The camshaft position sensor can go bad.
I have a new digital camera, and hope to get a good picture of it to add to my pictures.
It is pretty hard to see....but it is located on the passenger side of the motor....at the end....below the power steering line and IMRC actuators.
The connector can go bad as well is the internals.
The sensor is held in place by 2 small bolts on the top.
You don't want to loosen anything else...as you don't want to change the position of the syncro gear.
This is all that is left of the "distributor" of the old cars.

Another thing that I thought of is fuel pressure.
Has your fuel filter been changed recently?

I am trying to keep on cheap and easy before thinking of expensive and difficult things.

I am sure that you are aware that there are a lot of vaccum lines behind the upper intake manifold....and I would hate to have you spend a bunch of money and then find out it was a vaccum line.
I am guessing that your heat in the vehicle is working correctly?....specificaly the selection of defrost, heat and vent.....as these are vaccum driven.

[_pete_]

Originally Posted by wiswind

The camshaft position sensor can go bad.
I have a new digital camera, and hope to get a good picture of it to add to my pictures.
It is pretty hard to see....but it is located on the passenger side of the motor....at the end....below the power steering line and IMRC actuators.
The connector can go bad as well is the internals.
The sensor is held in place by 2 small bolts on the top.
You don't want to loosen anything else...as you don't want to change the position of the syncro gear.
This is all that is left of the "distributor" of the old cars.

Another thing that I thought of is fuel pressure.
Has your fuel filter been changed recently?

I am trying to keep on cheap and easy before thinking of expensive and difficult things.

I am sure that you are aware that there are a lot of vaccum lines behind the upper intake manifold....and I would hate to have you spend a bunch of money and then find out it was a vaccum line.
I am guessing that your heat in the vehicle is working correctly?....specificaly the selection of defrost, heat and vent.....as these are vaccum driven.

Yep. Heat is all working properly. Well, the rear heater doen't blow hot but it never has in the three years I've owned the van.
I checked all the rear vac lines while I had the wiper cowl off when changing plugs.

A new fuel filter will go on tonight after work. Probably a new air filter as well.

Can the cam sensor be turned like a distributor? Or does it just get replaced?

The only other things I can think of that may be the problem are the fuel pump (it was a little noisy on occasion but has been quiet for a while), vehicle speed sensor (looks like a complete pain to change), or maybe an exhaust leak.

I had a small issue very recently that may or may not be related. I was on the highway and noticed the speedo was reading about 20mph high and the needle was shaking. (the rpms were around 2200 in od gear and the speedo was showing 85mph!) It only did that once and never has happened again.

[_pete_]

Thanks for the help wiswind. I appreciate the ideas but I got it fixed!!!

The problem was...fuel pump.

I wasn't getting any CEL codes so that got me thinking that it had to be something outside the OBD-II system. I believe the fuel pump is not covered by the OBD.
I mentioned earlier that the pump used to be noisy but was quiet now since the problem started. I think whatever was making the noise must have broken.
BTW, I need to kill the guy that thought up the locking ring that holds the fuel pump assembly. That thing was brutal to remove and reinstall. Would a few bolts have been too much trouble?

The van has 175K on it now and I should be able to wring another 100K out of it. It now has new plugs, wires, coil, air filter, fuel filter, fuel pump, brakes, tires, and a rebuilt tranny (the old one exploded a few weeks after I bought the van but that's another story).

I should be good to go but I'll keep this site bookmarked for the future.

It was a complete pain of a job to do but it's done and after a quick test drive, the van runs great.

[wiswind]

You are correct, the fuel pump pressure and fow are not monitored by the OBDII system.....that is why I mentioned replacing the fuel filter and checking the fuel pressure.
As mentioned in a couple of other posts, folks have found checking the fuel pressure at idle to not always get them to the problem......as it dropped under load......so monitoring the fuel pressure while driving is needed for that.
I was hoping that it would be something cheaper and easier than a fuel pump.....which is why I like to recommend looking at other things first.

I did read someplace about how a clogged or restricted fuel filter can place an additional load on the fuel pump.....which makes me recommend keeping the fuel filter changed more regularly than I have in the past.