1995 Windstar

Hi I have a 1995 Windstar with a 3.8L engine. It started idling rough, then over the next while it started losing power, then won't rev over 3,000 and also going uphill bogs down with preignition.

I put my code reader on it (as it is one of the first OBD II s) and it gave me a code 171 and 174 indicating lean on both banks. After some searching I found a TSB on faulty MAF sensors so thought this was a likely canidate.

I took it to the local repair facitlity which after a week and a half threw up their hands and told me I should take it to Ford as they didn't have the resources to troubleshoot it any further. They checked the following, removed and cleaned the MAF sensor, checked for external vacuum leaks, did a compression check which they said was okay, found that the vacuum was only 10.5 inches, they also said that the plugs looked good and that I had 42 PSI of fuel pressure. There is nothing apparent in the exhaust, oil or coolant.

I retrieved the van from the garage after forking out almost $350 to find out basically nothing then took it to Ford.

After taking it to ford they checked it over and said that they thought it was a mechanical problem and wanted to perform a compression test again as they didn't believe that it was good. So I told them to go ahead and have not heard back from them yet.

Apparently the previous owner had the head gaskets replaced 2 years ago and that is about all I know about the previous history of it.

I also understand that later year Windstars have had problems with the intake manifold, port seals and such but I see no mention of this problem of it in earlier models so don't know if this is a possibility or not.


Can anyone help me out with similar experiences or if there is any know issues with the intake manifolds on 1995's.


Thanks in advance.

Well 2 separate garages are questioning compression in at least one cylinder so that is most likely a definite possibility (I assume you didn't tell Ford up what the other shop did). I would not have first suspected compression based on what you had described.

I would suspect an intake leak or the MAF as the first shop thought. Cleaning the MAF was a good guess. The fact that the "lean" condition is being measured on both banks leads me to believe something common to both banks. I think the head gasket or valve guides etc.... theory would suggest at least one bad cylinder on both banks. (both head gaskets for example). although possible I tend to think a 2nd search for a vacuum leak would be a good idea. I wonder if it is possible for the head gaskets to leak to allow air in the intake stream only and leave the oil, coolant and combustion chambers/passages intack.

I know the 95s had a history of head gasket failures. Your year is not one for the Isolator bolt TSB. I always thought normal fuel pressue was closer to 90 psi - but I don't remember why I think that. Was the vacuum measured at idle?

I am surprised the first shop gave up. I think they did a good check of the obvious. Did they tell you why they ruled out a vacuum leak? Did they think the vacuum was in the expected range?

Please let us know what Ford says.

Well 2 separate garages are questioning compression in at least one cylinder so that is most likely a definite possibility (I assume you didn't tell Ford up what the other shop did). I would not have first suspected compression based on what you had described.

I would suspect an intake leak or the MAF as the first shop thought. Cleaning the MAF was a good guess. The fact that the "lean" condition is being measured on both banks leads me to believe something common to both banks. I think the head gasket or valve guides etc.... theory would suggest at least one bad cylinder on both banks. (both head gaskets for example). although possible I tend to think a 2nd search for a vacuum leak would be a good idea. I wonder if it is possible for the head gaskets to leak to allow air in the intake stream only and leave the oil, coolant and combustion chambers/passages intack.

I know the 95s had a history of head gasket failures. Your year is not one for the Isolator bolt TSB. I always thought normal fuel pressue was closer to 90 psi - but I don't remember why I think that. Was the vacuum measured at idle?

I am surprised the first shop gave up. I think they did a good check of the obvious. Did they tell you why they ruled out a vacuum leak? Did they think the vacuum was in the expected range?

Please let us know what Ford says.

Thank you for your reply, I told the 2nd garage ( the Ford Delearship) everything that I could remember from the first garage. They still insisted on a compression test in case the first garage did it improperly. The first garage did a propane vacuum leak test and told me that the vacuum was only 10 inches. I am not sure where they sampled the vacuum from, but Ford when they measured the vacuum got 11 inches which is still too low.

Apparently 40 psi is normal fuel pressure for this engine, so they have ruled out the fuel. I am not sure if the vacuum was measured at idle and also if the fuel was measured under load.

I agree that it is something common to both banks, the thing that puzzles me is why it happened so fast and to both if it is cylinder head related.

When I phone Ford today I am going to ask them some more direct questions, such as how hard they looked for a vacuum leak.

Also last year the computer was changed out due to it dumping so much fuel into #3 cylinder that it was actually coming out the exhaust pipe. I am a little worried that the fuel may have caused the cylinder bore to be damaged, but it has been almost a year and there has been no problem until now. Also it is only one bank and if the cylinder was damaged I would expect to see some indication in the exhaust or plugs.

I am losing quite a bit of sleep on this van right now, so appreciate any ideas on this. I will update today when I talk to Ford today.

Update, got a call from Ford said that the compression test was fine 165 - 170 on all cylinders. They said that they did an external vacuum check and now want to dive into pulling the intake manifolds out. I have decided that I am going to retrieve the vehicle and with the kind use of a friends garage I will do the work myself. They quoted me $600 to do this, the gasket set is $34 so I feel that doing the work myself would be far more economical. I am a Marine Engineer by trade so I am not unfamiliar with overhauling machinery, so I feel that this is the next course for me to take.

Here is where I am with this. I took the engine down as far as removing the lower manifold. Didn't notice anything obvious, carefully cleaned the surfaces and installed new gaskets. Just ran it up and running rough at idle and no power when I test drove it. I didn't check the vacuum yet as I can't find my vacuum gauges but suspect that it is still low. So unfortunatly I am no further ahead.

Is it running rough at idle?
If so, I would remove the fat vaccum line that goes from the upper intake manifold to the brake power boost unit....at the brake unit end. Plug that line (thumb works fine) and see if the idle smooths out.
You do NOT want to drive the van with the power brake vaccum line removed, as you will have no power brakes. But if you can do this check to see if the brake unit is causing the vaccum leak.

If this does not help, try the PVC line at the intake manifold...and plug that at the intake manifold..... I am not familiar with the '95.... but my '96 has a lot of things going off of that line.

You can try this with other vaccum lines as well to try to track down the cause.

Take note, that removing some of the vaccum lines may cause a variety of error codes to be set....so ignore the codes that you get while doing this.

If the EGR valve were stuck open, I would think that you would be getting EGR codes and, if it were causing this level of a vaccum leak, I doubt that the engine would run at all.

The Heater and A/C controls also run off of the vaccum from the intake manifold.

Thank you for your reply Wiswind, this is what I did today.

I teed a vacuum gauge between the fuel pressure regulator and the the manifold. When I started it up I had a steady 10.5 inches of vaccuum.
I unhooked the brake booster vaccuum line and plugged it with no increase, then unhooked all the other vaccuum lines and plugged them with no increase in vaccuum. I unhooked the exhaust line going into the egr valve and plugged the port on the egr where I removed the line with no increase. When I increase the speed to about 2000 plus the vaccuum drops to about 4 inches.
I have heard that this can indicate a plugged exhaust system, however the first garage said they unscrewed one of the oxygen sensors and put a gauge on it and it indicated a reasonable flow however I wonder if one side has good flow and the other doesn't? I am considering loosening of the collector pipes to see if I can temporarily increase the exhaust flow to see if this increases the vaccuum. ( I don't envy having to crawl under and do this though but...........)
This van is driving me crazy, any advice is much appreciated.

Thanks

The '95 has a different upper and lower intake manifold, so I am not familiar with it. I can still see the possibility for a vaccum leak by the method that you used, as it only takes a slight leak to cause a problem.

Another thing to try is cleaning the MAF with a non-residue electronic cleaner. There are 2 thermistors inside there.....and you want to flush any dirt / oil off and away from them.

Hello Epromman, welcome to my world. (95, 3.8L 175K mi.) Wiswind is right. Vaccum leak between the MAF sensor and the Intake will definitely cause your symptom. I don't believe this is the problem because you don't here the "sucking sound". I tracked down my last vaccum leak by sticking my head under the hood, pulling on the accelerator wire, and tracked down the sucking sound to the hole in the rubber intake hose (where the plastic tube from the front valve cover is supposed to be stuck into it). My experience with your problem has been (on two occasions) Ignition. Check your coil pack. Label and pull all the plug wires off the pac, and pull the #4 plug from the block. Have a buddy throw the ignition key while you check all the terminals on the pack, by grounding the plug (with a gloved hand) and verifying a good arc. Post again if you need more help.

Just like in the old days, it's still "ignition first". I recall that this coil pack operates like that of a Japanese inline 4 motorcycle. The spark goes into one plug from the coil, across the block, and into the return through another plug. In this manner, one bad coil or coil wire affects two cylinders. This would explain both banks getting codes. It doesn't explain the low vacuum, though. I used to attribute that to EGR or vac booster. Are you sure that the EGR is closed? Just because you removed the vacuum line to it, doesn't mean that it isn't stuck open. Your car would chug like a steam engine with that thing open partially. I'd remove it, plug the opening, and test again.
Good luck!
Marc/Atlanta

98er,s got a point. I check my EGR valve by pulling it off the van this way. Pull the tube off the top of the thing and suck on it. If it doesn't hold a "suck" then its shot.

Karl

Thank You for all the suggestions I am going to see if I can get some help from a friend tomorrow night and go through them. I did unhook the metal exhaust tube going into the egr and plugged the port with a vinyl glove and didn't notice any change in vacuum however it sounds like it might be a good idea to revisit it. I did pull out one of my oxygen senors to try and reduce back pressure on that bank to try to rule out plugged convertor however I will have to jack the van up and crawl underneath to get at the other bank one.
It seems that I can not fully rely on the troubleshooting done by the other garages and will have to take a start from square one approach and retest everything for myself. I will let you all know how I make out tomorrow.

I pulled the other banks inlet oxygen sensor with no increase in vaccuum, so it appears the exhaust isn't choked. Removed the EGR valve completely and plugged the hole in the manifold with my thumb, the vaccuum increased a couple of inches, the old gasket seemed questionable so will make a new one tomorrow and reinstall it after I test the valve out. I am next going to check the coil pack, the resistance of each injector coil at the connector at the end of the harness then the resistance of each wire. Out of desparation I will check out every little thing I can.

Concerning EGR valve. Sucking hard on the small tube on the top opens the valve, follow me now.

Remove the EGR valve.
Clean it the big holes as best you can.
Try to blow through either where the EGR Pipe goes into the valve.
No air should pass to the manifold side.
If you can blow throught the thing, either clean it more or replace it.

Now, suck on the small tube going into the top of the thing.
It should be very hard to do. If you can draw air through the small tube, the diaphram is shot. Replace the EGR.

If it passes these two tests. It's fine. Go on to the coil pack.

When the guy had the headgaskets replaced, did he do a head job? (Valve guides, re-lapped etc). If not, you can remove the heads and bring them to a shop, it should cost you less than $400, and boy does that make a difference!! It seems that valve guides are more prone to allowing Oil into the Combustion chamber than The newest headgaskets are called MLS (Multi lay steel)

Golly, I've gone too far. I didn't mean to blather on about a waaay lot of work. Just check the coil next.

You're going great. Treat this like a puzzle. Puzzles take time. What you're doing is detective work. It's an old car. Anything could be wrong with it. To have a shop fix it would cost a fortune.

You will find your problem.

Karl

Myself, when I was trying to track down a intermittent miss, I replaced these parts, one at a time. Coil Pack, EGR valve.
Just do to the work involved messing with them as well as their age.
Thing about the EGR valve, if it were not working correctly, you should get a code as the DPFE will not be seeing the correct values.
To remove the pipe from the EGR valve, I would soak it good with PBlaster, or Seafoam, to help loosten up the threads.

Coil pack? The failure that can happen is arcing through the epoxy, resistance values can look great, you might be lucky and see cracks in the epoxy and / or carbon tracking.

I am also wondering about the fuel system, can drive you crazy also.
Is it delivering enough fuel?
The fuel pressure will be different under different engine loads.
The fuel pressure regulator has a vaccum line to it.
The lower the intake manifold vaccum, the higher the fuel pressure at the fuel rail.
Higher vaccum gives you lower fuel pressure.
The idea is, to give the engine more pressure in the fuel rail under greater engine load.
If the fuel filter is clogged, or the fuel pump is not giving enough flow, it can cause the engine to run lean, and miss.

The CHEAP and easy in me says to replace the fuel filter.
It may or may not be your problem, but I would eliminate the cheap and easy stuff first......

Thank you everyone for your suggestions, here is where I am.
Removed the egr valve cleaned it and the manifold where it bolts on to, made a couple of gaskets for it. I first put a gasket with only bolt holes so that it blocked the port on the manifold to see if it made a difference in vacuum. This made no difference so I can pretty safely eliminate the EGR valve as a suspect so I removed the valve and put a proper gasket on.

Next I moved my vacuum gauge to another port on the manifold, just in case the hose I had it on was partialy blocked, had and orfice or some other factor that might affect the vacuum reading. This made no difference.

I then went to the coil pack and with the aid of a friend watching the tach I removed the leads there one at a time. They all caused a drop in rpm except for the #1 cylinder so it appears it is missing on that cylinder also when I remove the wire from the coil pack for that cylinder sparks arc out of there and the others show no arcing when the wires are removed.

I don't know if 1 cylinder not firing could account for low vaccuum but it sure would indicate a rough idle.

I will have to check the wire next and plug as well but, the arcing at the terminal on a cylinder which is not firing is a little too coincidental.

Once again thanks for all the encouragement and suggestions.