Check Engine Light

I have a 1996 Ford Windstar with a 3.8L engine. Mileage is around 70,000. The check engine light keeps coming on and stays on. A mechanic next door resets this and let me know what the code means. The other day, he said there was misfiring going on in cylinder 4, but resetting took care of this. He also recommended that I change my battery as he was showing voltage drops. I did replace the battery and a few miles of driving and the light came on again. Not sure what could be goig on. My exhaust smells very rich. Also, during acceleration and deceleration, engine seems to run great. However, at 30 plus mph, when trying to maintain a speed, let's say 35mph, the engine runs as if it is skipping (misfiring) and engine seems to really struggle. If I decelerate and then accelerate, runs fine, but maintaining the speed (any speed above 30mph) misfires.

I have a 1996 Ford Windstar with a 3.8L engine. Mileage is around 70,000. The check engine light keeps coming on and stays on. A mechanic next door resets this and let me know what the code means. The other day, he said there was misfiring going on in cylinder 4, but resetting took care of this. He also recommended that I change my battery as he was showing voltage drops. I did replace the battery and a few miles of driving and the light came on again. Not sure what could be goig on. My exhaust smells very rich. Also, during acceleration and deceleration, engine seems to run great. However, at 30 plus mph, when trying to maintain a speed, let's say 35mph, the engine runs as if it is skipping (misfiring) and engine seems to really struggle. If I decelerate and then accelerate, runs fine, but maintaining the speed (any speed above 30mph) misfires.

I had the same thing happen about two years ago.It turned out to be carbon build up in the EGR Ports. Took it into the garage and they cleaned it and it has been running smooth up until about 3 weeks ago. The light came on again and I was told a misfire cyl #2 and lean. The mechanic(who I trust) said he would change the fuel filter and the spark plugs. I would go with cleaning of the ports as it is the cheapest then the filter and plugs. Hopefully this will help! Not much of a mechanic!!

I have a 1996 Ford Windstar with a 3.8L engine. Mileage is around 70,000. The check engine light keeps coming on and stays on. A mechanic next door resets this and let me know what the code means. The other day, he said there was misfiring going on in cylinder 4, but resetting took care of this. He also recommended that I change my battery as he was showing voltage drops. I did replace the battery and a few miles of driving and the light came on again. Not sure what could be goig on. My exhaust smells very rich. Also, during acceleration and deceleration, engine seems to run great. However, at 30 plus mph, when trying to maintain a speed, let's say 35mph, the engine runs as if it is skipping (misfiring) and engine seems to really struggle. If I decelerate and then accelerate, runs fine, but maintaining the speed (any speed above 30mph) misfires.

How much did that cost (the original port cleaning)?

he said there was misfiring going on in cylinder 4, but resetting took care of this.

Resetting only shut off the light. It did not take care of the misfire. This is why the light keeps coming back and why you are having drivability concerns.

The suggestion to clean the EGR ports is a good one as that can certainly cause your problem. One way to know for sure is to temporarilly disconnect the vacuum line going to the EGR valve and plug it. This will disable the EGR system. You can then test the vehicle under the came conditions that cause your problems. You will get different errors but they will clear up on their own after the test.

Replacing fuel filters is always a good idea if it is due. There are other items that can cause a misfire such as bad cables, spark plugs, dirty injectors, low fuel pressure...... Obviously these will need more investigation to know for sure but ensure that the items that should be changed as maintence are changed.

Resetting only shut off the light. It did not take care of the misfire. This is why the light keeps coming back and why you are having drivability concerns.

The suggestion to clean the EGR ports is a good one as that can certainly cause your problem. One way to know for sure is to temporarilly disconnect the vacuum line going to the EGR valve and plug it. This will disable the EGR system. You can then test the vehicle under the came conditions that cause your problems. You will get different errors but they will clear up on their own after the test.

Replacing fuel filters is always a good idea if it is due. There are other items that can cause a misfire such as bad cables, spark plugs, dirty injectors, low fuel pressure...... Obviously these will need more investigation to know for sure but ensure that the items that should be changed as maintence are changed.

So if I disconnect the vacuum hose and plug it to disable the EGR system and then drive and if I do not notice the problem, does that then mean the problem is definitely a clogged EGR port?

It would certainly support the theory.

And warrant exposing them to have a look.

There is 1 EGR port in the lower intake manifold for each cylinder. Cylinder #1 and #4 are the farthest away from the EGR valve, and seem to be the last ones to become clogged. So, when the other ports become clogged, ALL the EGR gasses end up going to 1 or 2 cylinders, causing the "missfire".
Pulling and plugging the hose to the EGR valve will disable the EGR system. Please take note that this will cause the Check Engine Light (CEL) to come on as the computer has sent out a command to open the EGR valve....and is expecting to sense EGR flow.
The EGR valve does NOT open at idle....so you will need to take the car for a drive.
What you are looking for is, "Does the engine still have a miss?". If so, then the problem is most likely something else.
If it does not, then you will want to have the EGR ports cleaned.

I had a missfire on cylinder #4 that was caused by clogged EGR ports at 135K miles.
Then several months later.....I got a slight miss...that I was chasing for another several months until it also lit the CEL....and was a miss fire on Cylinder #1....caused by crud on the end of the fuel injector.

Neither issue is a major repair, but should be repaired.

A link to some pictures from my '96 windstar follows.


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

I had the same thing happen about two years ago.It turned out to be carbon build up in the EGR Ports. Took it into the garage and they cleaned it and it has been running smooth up until about 3 weeks ago. The light came on again and I was told a misfire cyl #2 and lean. The mechanic(who I trust) said he would change the fuel filter and the spark plugs. I would go with cleaning of the ports as it is the cheapest then the filter and plugs. Hopefully this will help! Not much of a mechanic!!


I think that I only ended up paying $35.00 for it since I had complained several times about the engine light. I think they were happy to give me this rate to avoid anymore confrontation. Probably best to call a garage and get an idea.From what I've been told, changing the plugs in itself is a good days work if you are not familiar with the setup, so from a garage point of view could be a little more costly than a egr cleaning!!

Resetting only shut off the light. It did not take care of the misfire. This is why the light keeps coming back and why you are having drivability concerns.

The suggestion to clean the EGR ports is a good one as that can certainly cause your problem. One way to know for sure is to temporarilly disconnect the vacuum line going to the EGR valve and plug it. This will disable the EGR system. You can then test the vehicle under the came conditions that cause your problems. You will get different errors but they will clear up on their own after the test.

Replacing fuel filters is always a good idea if it is due. There are other items that can cause a misfire such as bad cables, spark plugs, dirty injectors, low fuel pressure...... Obviously these will need more investigation to know for sure but ensure that the items that should be changed as maintence are changed.

I disconnected the vacuum line going to the EGR valve and plug it as noted above. I drove my van around and still noticed the problem while driving and maintaining at 35 mph. Any other thoughts on what might be causing this? Thanks

There are MANY possible causes of misfire.
I have read posts of people making many trips to the dealer to have this and that done....and spending a lot of money.....

If many things like spark plugs, fuel filter, PCV valve....are original.....They are comming due....
So I would recommend a "tuneup" at a reputable shop.....I have a dealer that I trust for things that I do not do myself.
This will eliminate inexpensive things that you should do anyhow in the near future....and in a "tuneup package" should save you money and time. If you have it done......ask them to look at the plugs as they can give you an indication of problems present.


Other things to look for....any vacuum leaks......They can be hard to locate as there are a lot of locations this can happen at. The problem with vacuum leaks is that this is air that the computer does NOT know about.
Airflow is measured by the Mass AirFow (MAF) Sensor ....which on the '96 is the other half of that round "barrel" that contains the air filter. The MAF can be cleaned with a non-residue electronics cleaner.
There are 2 thermal devices inside the plastic "bar" that is inside the MAF assembly. Together, they measure the airflow.....and tell the computer how much air is going into the engine....so a little dirt on them can cause an inaccurate reading.


A good quality fuel system cleaner (Redline Complete Fuel System Cleaner is highly rated...and is now sold at Advance Auto Parts) is a good thing to do at LEAST once a year.

There are MANY possible causes of misfire.
I have read posts of people making many trips to the dealer to have this and that done....and spending a lot of money.....

If many things like spark plugs, fuel filter, PCV valve....are original.....They are comming due....
So I would recommend a "tuneup" at a reputable shop.....I have a dealer that I trust for things that I do not do myself.
This will eliminate inexpensive things that you should do anyhow in the near future....and in a "tuneup package" should save you money and time. If you have it done......ask them to look at the plugs as they can give you an indication of problems present.


Other things to look for....any vacuum leaks......They can be hard to locate as there are a lot of locations this can happen at. The problem with vacuum leaks is that this is air that the computer does NOT know about.
Airflow is measured by the Mass AirFow (MAF) Sensor ....which on the '96 is the other half of that round "barrel" that contains the air filter. The MAF can be cleaned with a non-residue electronics cleaner.
There are 2 thermal devices inside the plastic "bar" that is inside the MAF assembly. Together, they measure the airflow.....and tell the computer how much air is going into the engine....so a little dirt on them can cause an inaccurate reading.


A good quality fuel system cleaner (Redline Complete Fuel System Cleaner is highly rated...and is now sold at Advance Auto Parts) is a good thing to do at LEAST once a year.


My mechanic looked at the code and it definitely was the #4 misfiring. He removed the fuel injector and cleaned it, did a number of tests on it such as fuel pressure, etc. The tests were fine. He replaced the plug even though it did not show any unusual wear. He reset the code. So I tested the EGR using the vacuum method described, the mechanic did these tests, and now the check engine light turned on again. Any other ideas? I live in a state that has emission testing and I am now up for license suspension until I can get this thing fixed. Please help !! Thanks.
Is there anything else that can be looked at before tearing apart the engine for a faulty valve, push rod, lifter, rocker, or cam?

PLEASE TAKE NOTE:....Before trying anything else.... Disabling the EGR system as mentioned will very likely cause the Check Engine Light (CEL) to come on. This is because it is sensing "Insufficient EGR Flow". Which is due to the EGR valve being disabled. You may want to have your codes read (can be done for free at Autozone). If you still have the missfire with the EGR system disabled, you most likely have another problem. If your engine seems fine (except for the CEL) then you may have an EGR problem. You can make the CEL go off by removing the negative battery cable....leaving it disconnected for a while (like 5 min) and reconnecting. This will also clear some data from the computer that is used for "drivability". It will take a while for the computer to "relearn" this data. However, it should not cause the CEL to come back on, or any missfire. Any lack of performance that you would notice while the computer relearns "drivability" information would be relative to transmission shift points (speed and RPM that the transmission shifts at), acceleration, and such.


To get to the fuel injectors on the '96 3.8L, you remove the upper intake manifold....which would expose the EGR ports. If they were clogged, it would be obvious at this point. Most any experienced mechanic would have noticed if they were clogged. They clog right at the surface of the port....the part that you see at this point.
So....I would guess that they are fine as your mechanic was in there....you could ask if you are not sure.

One thing that I would try.....(requires removal of the upper intake manifold again) is to swap the #4 fuel injector with another cylinder. It is possible that your mechanic did this. This would eliminate the injector as the cause.

Also, I read another post......At flatratetech.com of a person having a missfire problem.....and it turned out to be a problem with the wiring between the PCM and the injector..... Required following the wiring harness....and verifying connections.

A lot of other things that can cause missing.....would most likely impact all the cylinders....so having the code limited to missfire on cylinder #4 narrows things down a lot.


I would not be quick to suspect faulty valve, etc....but if you wonder about it....after all else fails.....a compression check should help in the diagnosis.

You could also ask your mechanic to do a vacuum check on the intake.....to see if it is stable....and within reasonable range.