How do you fix a recurring number 4 cylinder misfire diagnostic code on a Windstar 3.8L engine after changing sparkplugs and wires?

Answer 1

You may have something wrong with that cylinder that is causing a loss of compression or a loss of combustion on that cylinder. Those things were notorious for head gasket deterioration, which caused coolant to enter the cylinder, leading to a misfire, esp on initial start up.

Also, you may have a faulty coil tower on your coil pack. I have seen many coil packs needing replaced due to one coil failing on it. You also have 6 injectors that are fired by the computer. If you have a problem with the #4 injector, the #4 injector circuit, or the #4 injector driver in the computer, that would lead to a P0304 code.

Another situation I see frequently: If that engine has individual EGR ports to each cylinder, located in the intake manifold (some from about 96 on did), you may have a situation where all but #4 are stopped up. What happens is, when the EGR is commanded on, the imbalance of EGR gasses entering the cylinders causes that cylinder to go excessively lean in comparison with the other cylinders, thus causing a misfire on that cylinder.

It is never good to just blow parts on a vehicle when you have a trouble code and a check engine light. You need to determine what could cause a cylinder to misfire. The main causes of misfire to a cylinder are lack of ignition, lack of fuel, air/fuel to lean to that cylinder ( a vacuum leak right near that cylinder can also cause this), Loss of compression, or coolant entering cylinder. Answer

WINDSTARS HAVE A COMMON PROBLEM WITH THERE EGR PORTS(IN THE LOWER INTAKE MANIFOLD) PLUGGING UP WITH CARBON -IF YOU REMOVE THE UPPER PLENUM(UPPER INTAKE USUALLY BLACK PLASTIC HOUSING ON ENGINE)YOU CAN CLEAN THE PORTS OUT WITH A SMALL PICK-THIS PROBLEM WILL CAUSE A MISSFIRE CODE EVERYTIME Answer

I have a 98 Windstar and about two years ago the check engine light turned on. I asked my neighbor, who is a mechanic for a local Ford dealership, about it. He said that a Ford mechanic is the only one who can "turn it off". They have a computer that they plug into the engine and tells you what is wrong. Then they are the only ones whe have a code that turns the light off. In my case it was cracked 3" long rubber air tube.

We had the same problem with our '96 Windstar. #4 & 5 cylinders came up in the computer as being bad. New plugs & wires helped #4, but #5 was still showing bad. Turns out, even though the injector code did not show up, 2 of the injectors were bad. This took care of the light problem. We did NOT have to go to a Ford dealer in order to get the light to go out... your regular mechanic should have diagnotic tools and be able to "flush" your computer's memory of the bad codes. Answer

I have the same problem on my 96 windstar with > 100000 miles. This is apparently a common problem with high mileage windstars (3.8L) and assuming sparks, fuel, injectors, o2 sensors etc. check out OK, it is caused by the build up of carbon in the EGR orifices in the lower intake manifold. The problem can be fixed by removing the upper intake manifold and cleaning the carbon deposits from the EGR orifices. The misfire happens because the orifices on ports 2,3,4,5,6 get blocked first (#1 furthest from EGR valve) therefore when the EGR valve opens, most of the recirculated exhaust gases go to #1 cylinder weakening the mixture excessively resulting in misfiring.

-- I had the same problem on my 96 Windstar @ about 100k miles and received the same diagnosis of carbon buildup on the intake manifold. We removed the manifold for thorough cleaning and discovered a blown manifold gasket at the #1 cylider.

i had the same problem with my van, I took it to the dealer and they checked it out as being the coil going bad. so far so good with it. Answer

did you disconnect the neg battery termanl to reset your CPU & if so do you still have the miss it could be a coil or wire Answer

I had the same problem on my 1996 Windstar and found that the #2 fuel injector was bad Answer

The plug, wire or coil could be the problem.

Usually if the injector is failing you will get different codes.

I just replaced plugs and wires from a 2002 and they were in very bad condition. The van had 90,000 or so miles on it. When these were changed it ran like a new van.

The back three plugs were just awesome. (sarcastic) That is another issue though. Good luck.

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Answer 2

#4 is rear head center lifters are not bleeding off pressure and holding valve open or bad injector. Had a #5 cylinder misfire replaced lifters problem solved.