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2002 ford windstar: I am having problems with the engine

Customer Question

I have a 2002 ford windstar. I am having problems with the engine. It seems to be missing. In nuteral as I increase the rpms it starts to miss at 3500-4000 rpms. Also sometimes when I am driving it appears to miss , hesitate then continues to run. When cold lately it is running very rough and missing. At this point I am afraid to take it on the road for fear of shut down. To this point I have changed the plugs , not for this problem, rather when I had to change the intake gaskets I figured it was easy to change the plugs . Car ran well for about 5000k miles Then this problem started. I then changed the plug wires. The problem is still with me... Is the ignition coil the next thing to consider? Tony Campanelli
Submitted: 6 years ago.
Category: Ford
Expert:  AMEDEE replied 6 years ago.

Hello there!


Yes... you might have a bad ignition coil. Any part of the secondary ignition will do this including the ignition coil or coils! This sounds like a classic ignition misfire! They usually go bad under a load like under acceleration, but can be noticeable at any time. It is very important to have your engine equipped with good tune up parts or you may be causing damage to other components of you car like the catalytic converter which can be expensive!


Possible causes:

Ignition misfire causes by any bad tune up part and or ignition coil or coils.
Bad spark plugs, spark plug wires and cap and rotor (if equipped)
Wrong tune up parts spark plug, wires etc...

Insulator cracks.
Improper gap.
Burned electrodes.
Heavy deposits.


The quickest way to check the ignition components, is by looking closely for leaking secondary voltage. Visual look at all the tune up parts to see if you can see any sparks coming from any of the wires or coil (or coils) when the vehicle is running. If not, you can put your hand on the coil/coils and wires when the engine is running and see if you feel any small voltage leaking form the tune up parts. Check spark plug wires by connecting ohmmeter to ends of each wire in question. If meter reads over 30,000 ohms, replace wire(s).
ALso, with engine running, spray coils and plug wires with fine water mist to check for shorts. It will leak secondary ignition voltage from the tune up parts caused by high resistance from carbon tracking if they are bad. This is very common if the tune up parts are not changed regularly!


If any is found, the tune up parts are simple bad an will need to be replaced! If none is found than you can spray a mist of water on the tune up parts when the engine is running and see if that causes the engine to stumble or run rough at all. Again, if it does, the tune up parts are bad and will need to be replaced!



Customer: replied 6 years ago.
If I can assume that the plugs and wires that I replaced are good then How do I check that the coil is or may be bad? what can I do to verifiy a problem with the coil? Also neglected to tell you that the vehicle has 185000 miles..
Expert:  AMEDEE replied 6 years ago.

Well, short of seeing sparks flying out of the secondary ignition, there is not a whole lot you can do without an ignition lab scope. You can try a soak test and spray a light mist of water onto the ignition components to see if they start to misfire. If so, they are bad and will and to be replaced.



Edited by AMEDEE on 12/3/2009 at 2:39 AM EST
Customer: replied 6 years ago.

Expert:  AMEDEE replied 6 years ago.

Do we have any codes in the computer?


WHat is fuel pressure at?


DO you have access to a scanner?

Customer: replied 6 years ago.
Expert:  AMEDEE replied 6 years ago.

There still can be codes in the computer even if the check engine light is not on.

Your local auto parts store will be able to scan it for free for you.


Also, you could have a bad fuel pump. I would rec to check fuel pressure. Fuel injected cars are very fuel pressure sensitive. Fuel pressure is very important and must be within specifications! But if the pressure is low, it does not mean the pump is bad. A plugged fuel filter, a pinched line, and low voltage at the pump can contribute to low fuel pressure. All three must be check before replacing the pump! You can get a fuel pressure gauge at a local auto parts store for cheap.

Expert:  AMEDEE replied 6 years ago.

I put together some tests for you to run so that we can pinpoint the problem.


The EGR flow on this vehicle leaves the valve and enters a large passage that runs through the lower intake manifold. From there it is fed to each individual cylinder through small orifices in each intake port. These orifices tend to become restricted with carbon, causing all EGR flow to enter the cylinders with no restriction creating a misfire on those cylinders. To test for this problem, simply unplug the vacuum hose from the EGR valve and road test. If the misfire is gone, remove the upper intake plenum and clean the passages in the lower intake manifold as needed



Tests/Procedures: 1. Disconnect the ignition coil and recheck for a flash on the test light on the PK/WH wire. If there is a good flash with the coil disconnected but not with it connected, suspect a shorted coil or a bad connection at the coil.

2. If there is no flash on the PK/WH wire with the coil disconnected either, access the Powertrain Control Module (PCM) connector behind the Right Front (RF) strut tower area.

3. Back probe pin 78 PK/WH wire and check for a trigger there with the test light still connected to battery positive and cranking the engine. If there is a good flash at the PCM connector but not at the coil, check the PK/WH wire for an open circuit between the two.

4. If there is no flash at the PCM connector, suspect a damaged PCM. Check for a shorted ignition coil before replacing the PCM. Also check the PK/WH wire for any continuity to ground or battery positive in the harness.


Potential Causes: Ignition Coil
Powertrain Control Module (PCM)

Tests/Procedures: 1. Start out with disconnecting the vacuum hose to the Exhaust Gas Recirculation Valve (EGR) and see if the problem is still there. If the problem is gone, clean out the EGR orifices, since clogged orifices will direct too much EGR flow to one or two cylinders. If the problem is still there, perform a manual power balance test while power braking to determine the cylinder that is misfiring.

2. Verify the cylinder in question has adequate spark. Use an inductive timing light on the cylinder in question. If the timing light stops flashing as the misfire occurs, the cylinder is losing spark.

3. If OK, check to see if the injector is losing injector pulse as the problem occurs. Monitor Long Fuel Trim (LFT) on the scan tool to see if it is abnormally high on the bank with the problematic cylinder which may indicate a restricted fuel injector.

4. If OK, perform a cranking and running compression test for mechanical problems.


Potential Causes: Engine - Base engine concerns.
Restricted Exhaust Gas Recirculation (EGR) Passages
Restricted Fuel Injector
Fuel Pump
Malfunctioning Secondary Ignition

Tech Tips: When performing an engine running compression test, remove the Schrader valve from the spark plug end of the compression tester hose so that the needle falls back to 0 PSI after each compression stroke. Disconnect and ground the spark plug wire. Start the engine and take an average of the peak of the reading on the cylinder. If necessary, connect a timing light to the plug wire so that a snap shot reading can be taken at the time of ignition. All cylinders tested should be within 10% of each other and the readings will typically be about 1/2 of that found from a cranking test.

Category: Ford
Satisfied Customers: 23934
Experience: ASE CERTIFIED TECHNICIAN ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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Customer: replied 6 years ago.
I finally gave up .. Could not make heads or tails of anything. The last thing I did was put higher grade gas in the tank. I don't think that was the solution. but I have had no problem since then. I also decided to bring the to a shop to put on and analyser, they had it for two days and could not find a problem. So until it happens again and more consistently I am in limbo and driving the van again..... Thanks
Expert:  Kenny Z. replied 6 years ago.

Hello, different expert here.


Running the engine at 4000 rpm in park or neutral causes the PCM to go into rev limit. The pcm alternately shuts down injectors to limit rpm. This is normal and programmed in from the factory. If you have a misfire under load while driving in gear then I would recommend A quick diagnostic at the ford dealer. They can retrieve cylinder misfire data, substitute a known good coil and perform a relative compression test and power balance test while road testing. We charge $98 for this service and it seems better then just trowing parts at it. I have also seen some issues where the number 2 or 3 spark plug becomes oil fouled and misfires. This is caused by the lower intake gaskets developing an internal vacuum leak and creating a vacuum in the valley area of the center intake spacer causing oil to be drawn into number 2 and sometimes number 3 cylinder. If this was the problem it would be evident on the spark plug it would show evidence of oil burning and would look different then the other plugs.

Edited by Kenny Z on 1/10/2010 at 4:03 PM EST
Customer: replied 6 years ago.
Like I said in my previous the shop put the van on an analyser and fuel pressure gauges with no luck... Thanks for your response and when the problem reaccures I will be back in touch....thanks again
Expert:  Kenny Z. replied 6 years ago.
Your welcome
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