1996 Windstar misfire

[atmk631]

Hi, I have a 96 windstar with a 3.8 and around 130000 miles on it. When the engine is warm and restarted the idle is rough(sometimes), no problems with a cold engine or when driving. Codes show misfire on #1 & #4. Occasonaly a system too lean (left bank) shows up. As I said this does not happen when engine is cold and I would like to have this figured out before my emissions test next month. I have changed plugs and wires. Any Ideas, Thanks

[shorod]

Does the 1996 Windstar use coil packs on the 3.8L? If so, do cylinders 1 and 4 share a coil pack? You may have a coil pack with an open internally. When cold, the windings contract slightly and make good contact. As the coil warms, the windings expand and have an intermittant open circuit, causing the misfire.

-Rod

[atmk631]

I'll check if it has the coil pack as this sounds like it could be the problem. However, could this cause the "system too lean" code to show up at the same time?

[wiswind]

The '96 3.8L does have a coil pack.
Also, the lean code could be a result of the PCM trying to deal with the misfire issue..... I have had that happen with my '96 3.8L.

One very common cause of misfire at cylinders 1 and / or 4 is clogged EGR ports.
The EGR valve is mounted on the driver's side of the lower intake manifold.....and the EGR gasses flow through a passage inside the lower intake manifold to a small 1/4 inch port for each cylinder.
The EGR ports clog right at the end....where the EGR gasses meet the oil vapors in the air intake.
The EGR ports clog closest to the EGR valve first....leaving the ports at cylinder 1 and / or 4 open....
With all the EGR gasses going to 1 or 2 cylinders, there is not enough oxygen in the air to that cylinder, causing the misfire.
The only code that I got when my EGR ports were clogged, was P0304.

I have pictures posted that show the ports.

The ports are easy to clean, once you get to them.
Be careful to avoid getting stuff down into the engine.

If you feel the misfire when it happens.....you can do a test.....
Temporarily remove the vaccum line that goes to the top of the EGR valve....and plug it.
Take the vehicle for a drive.
If there is no misfire.....then the problem was caused by clogged EGR ports.
If the misfire still happens, then the problem is most likely something else, as the EGR system has been disabled.
Take note that this test....disabling the EGR valve, will cause a code for insufficient EGR flow......as the PCM is trying to open the EGR valve....and is not able to.
Reconnect the vaccum line to the EGR valve.

If the problem was not the EGR ports......try taking a look under the hood with the engine running, when it is super dark out.
You are looking for any sparking from the spark plug wires, etc.

Another , less likely, but very possible is clogged fuel injectors.....
For clogged fuel injectors, I would use Berryman's B-12 Chemtool fuel system cleaner, that comes in a metal can.
You can get it at Autozone.

[atmk631]

Thanks for all the info. I am going to try the EGR test tomorrow. A misrfire in #5 showed up today. I wonder why it only happens on startup with a warm engine. It never does it when cold, or when engine has been running and then idling (i.e stopped at lights,etc) only after starting a warm engine. As soon as I rev it up for a few seconds it smooths out. Any ideas?
JB

[mustangmike351c]

if its too lean I would check injectors. no spark would bring up a too rich code instead

[atmk631]

Originally Posted by wiswind

The '96 3.8L does have a coil pack.
Also, the lean code could be a result of the PCM trying to deal with the misfire issue..... I have had that happen with my '96 3.8L.

One very common cause of misfire at cylinders 1 and / or 4 is clogged EGR ports.
The EGR valve is mounted on the driver's side of the lower intake manifold.....and the EGR gasses flow through a passage inside the lower intake manifold to a small 1/4 inch port for each cylinder.
The EGR ports clog right at the end....where the EGR gasses meet the oil vapors in the air intake.
The EGR ports clog closest to the EGR valve first....leaving the ports at cylinder 1 and / or 4 open....
With all the EGR gasses going to 1 or 2 cylinders, there is not enough oxygen in the air to that cylinder, causing the misfire.
The only code that I got when my EGR ports were clogged, was P0304.

I have pictures posted that show the ports.

The ports are easy to clean, once you get to them.
Be careful to avoid getting stuff down into the engine.

If you feel the misfire when it happens.....you can do a test.....
Temporarily remove the vaccum line that goes to the top of the EGR valve....and plug it.
Take the vehicle for a drive.
If there is no misfire.....then the problem was caused by clogged EGR ports.
If the misfire still happens, then the problem is most likely something else, as the EGR system has been disabled.
Take note that this test....disabling the EGR valve, will cause a code for insufficient EGR flow......as the PCM is trying to open the EGR valve....and is not able to.
Reconnect the vaccum line to the EGR valve.

If the problem was not the EGR ports......try taking a look under the hood with the engine running, when it is super dark out.
You are looking for any sparking from the spark plug wires, etc.

Another , less likely, but very possible is clogged fuel injectors.....
For clogged fuel injectors, I would use Berryman's B-12 Chemtool fuel system cleaner, that comes in a metal can.
You can get it at Autozone.

Hi, I pulled the vac line off of the EGR and plugged it a couple of days ago. There have been no misfire or lean codes since. only an insuffient EGR flow. I think that is the problem. Could you list the items (gasket,etc) needed for the fix.
Thanks

[wiswind]

No parts are needed.
You remove the upper intake manifold, and those gaskets are re-usable.....
You can see them in my pictures.....as well as the EGR ports.

Don't overtighten the bolts when you put things back together.
They give instructions for removing the upper intake manifold on the autozone website under vehicle specific repair guides.

I did not disconnect the accelerator cables.....I removed the throttle body from the upper intake manifold and set it aside.

[atmk631]

Took it apart today and noticed seepage from the lower gasket, so I took lower manifold off and put on a new gasket, cleaned the EGR ports, but those nylon(plastic stuff) called vacuum lines broke like straw. Had to improvise with really small flexible vac tubing that slid over the plastic. I started it up and so far so good, I am going to give it a good run tonight. Thanks for the help.
JB

[deathstar96]

I had exact same problem and disabling my EGR (plug EGR vacuum line) fixed the problem, now I will remove intake manifold and clear EGR passages, wiswind is the king of Windstar Repair knowledge, he has helped me several times over the years, I love my windstar and want to keep it on road as long as possible