codes PO304 and PO306 ?


Dorians
08-12-2005, 01:06 PM
I've just bought the '96 Windstar LX 3.8 a few days ago (I didn't know about the problems or this forum,Thanks God for it!) and the check engine light is on now all the time and since yesterday sometime is flashing.I took the van to Autozone and they gave me the codes PO304 and PO306 and the guy told me that I either need a tune-up or check for loose spark plugs or cables.I've told the guy about the egr ports and he said that this is not the case.
What shoud I do?
The van seems to be working fine,but I don't know if I sould take it to a mecanic or do it my self cause you guys help a lot of people here and you know more than other people that called themselfs ''experts'' on this field.
Thanks for all the help that I can get

Alan

wiswind
08-13-2005, 08:03 PM
P0304 is a misfire on cylinder #4...Front passenger side of engine.
P0306 is a misfire on cylinder #6....Front driver side of engine.

The P0304 is often caused by clogged EGR ports.
There is a port for each cylinder....and they start clogging on the driver side of the engine....closest to the EGR valve. The last ports to clog are cylinders #1 and #4....farthest from the EGR valve..... With the other ports clogged....all the EGR gasses then go to the remaining 1 or 2 open ports.....causing those cylinders to not have enough oxygen.....and the misfire.

The way to tell if it is clogged EGR ports is....ONLY TEMPORARILY disable the EGR system.
You do this by removing....and plugging the vaccum line that goes to the top of the EGR valve.
THIS WILL CAUSE ADDITIONAL FAILURE CODE(s)....for insufficient EGR flow.....which is OK.
I think that code is P0401....but should not cause the CEL light to blink.
With the EGR system temporarily disabled.....take the car for a drive.....and see if you get the blinking CEL or can feel the miss. If you do not....then the problem is with the EGR system.....very likely the EGR ports. If you still get the blinking CEL.....and feel the miss.....then you have another problem. You will need to take a drive....as the EGR system is not active all the time....it opens under certain drive conditions.....and should not be open at idle.

If the EGR ports have not been cleaned......You may want to do it.....and at the same time....remove the fuel rail (after releasing the fuel system pressure at the release valve at the front center of the fuel rail). Remove and clean the spray end of each fuel injector.
You will want to clean as best you can around each injector before removing them....to avoid getting any of that crud down into the engine.
I had a misfire on cylinder #2 that was caused by crud on the spray end of the fuel injectors.....and I noticed a BIG difference after cleaning all 6. I posted a couple of pictures of the crud and the spray end of the injectors. It did NOT clean off with the fuel system cleaners that I added to the tank.
I have seen posts here stating a dealer charge of $150 for a fuel injector cleaning with a machine.....and if it does the job....I would say that it is worth it.

If you have the original spark plugs.....or any plug other than a Motorcraft Double Platinum....you should replace them. Some have tried the Bosche plugs....and had problems. I get to the rear plugs by driving the front up onto ramps......let engine cool as you will be hugging a catalytic convertor.....and slide in under the car.....back far enough that you are looking up the front of the firewall...(in other words....if you went any farther back....you would be looking up at the floor pan)....you will be able to clearly see the rear 3 spark plugs....and reach up to them. Grab the spark plug wire by the boot that is on the plug....and twist it....clockwise and counter clockwise on the plug...to work it loose....then pull.

If you have the original spark plug wires....I would replace those as well.....with a good quality set of wires.

I would also run some fuel system cleaner through....you add it to the gas tank.
I would start with 3 bottles of the "treats up to 12 gallons" Chevron Techron Fuel System Cleaner. I think that the LX came with a 25 gallon gasoline tank. Another good brand...which I use in a "maintenance dose" is Redline Complete Fuel System Cleaner. It has lines on the side of the bottle for how much to add for each 10 gallons of gasoline.....and I add some with each fillup. The Redline has a lubricant that is good for the fuel pump.....injectors.....and intake valves.... You would add the whole bottle to do a periodic cleaning.

Replacing the fuel filter after having run the 3 bottles of Chevron Techron through would be a very good idea. The fuel filter is under the car....in front of the rear, driver side, wheel....on the inside of the frame member. It can be a pain to change on the '96....as 1 side has a plastic clip that you slide out to be able to remove the fuel line....but the front end of the filter has a crome connector that goes over then end of the fuel filter....and you need a plastic removal tool....that you slide up inside the crome connector to release the clips that are inside. You can buy the plastic tool at most auto parts stores....for under $10 for a set of various sizes. They are also used for air conditioning connectors. My set had instructions to use the 3/8" size for the FORD 5/16" fuel line connections. You will want to release the fuel system pressure....at the front center of the fuel rail on the engine before messing with the filter....as the fuel system maintains pressure for quite a while... You do not want a face full of gasoline.

I would also give the vaccum line elbow a look...on the top of the upper intake manifold....driver side.
Mine developed a leak on the inside of the elbow.
Can cause a variety of problems.

Give the air filter a look....if it has some oil (black soot) on it....replace it. If you have the soot on the air filter....I would also clean the MAF (Mass Air Flow) sensor. Use non-residue electronic cleaner. The MAF is in the big plastic part that you remove to get to the air filter.....it is in between the air filter and the engine. You will spray the cleaner in the front hole in the bar while holding the MAF assembly so that the cleaner runs out the hole on the back side of the bar....as I have shown in my pictures.

You will want to make sure that the transmission fluid is changed at LEAST every 30K miles.....21K miles for "severe service". Your '96 requires Mercon rated fluid. Do NOT use Mercon V. I use Mobile 1 ATF, which is a Mercon Rated fluid....and is a synthetic, which takes the heat, and flows better when cold. Better cold flow = smoother shifting in cold weather. The transmissions on mini-vans are weak.....so TLC is needed there.

I added a auxillary transmission cooler.

I also flushed my power steering fluid. The windstar is known for needing that every few years....as it gets hot and breaks down. I used Redline Power Steering fluid....which is a synthetic....and lists the FORD specification number that my owner's manual lists. You do NOT want to add...."Power Steering Fluid" to your windstar power steering resevoir. The owner's manual says to use Ford Power steering fluid....part #xxx or a fluid meeting Ford Specification #xxxx. You will not find the Ford Specification # on any bottle of power steering fluid at the auto parts stores.....
The '96 windstar power steering fluid is a "Type F" Automatic Transmission Fluid. In later years....they switched to a "Mercon" ATF.

I am using Wix oil filters...and Mobil 1 5W-30 motor oil. I change every 3K miles or so.

I have some Bar's stop leak in my antifreeze. The '96 windstar is not so bad for head gaskets..(the '95 was)...as long as you do not overheat the engine....but the lower intake manifold gaskets can leak.....into the cylinders. And the "Timing chain cover"...also called "Front Cover" can have it's gasket develop leaks. The "Front cover" is what the water pump, and the oil pump mount to. It is an EXPENSIVE, very labor intensive repair. The gasket is cheap....but the labor is the problem.
I did not use the Bar's "Original" pelletized stop leak.....I would use the "liquid aluminium" or the other kind that is in liquid or powder form. I would use ONLY Bar's brand.

You have 4 oxygen sensors. 2 "upstream" sensors......1 for the front bank of cylinders....and 1 for the rear bank of cylinders. And 2 "downstream" sensors. 1 after each catalytic convertor... The downstream sensors only monitor the catalyitic convertors to make sure that they are working. The upstream sensors are the ones that the computer uses to adjust the air/fuel mixture. They are NOT a high failure item. I am mentioning them because auto part store counter people often try to sell you oxygen sensors for "lean" codes. Lean codes are most often caused by a vaccum leak. There are codes that will tell you specifically if you have a bad oxygen sensor. So save your money. If you DO replace oxygen sensors.....I would use ONLY Motorcraft brand sensors....and I would replace them in pairs..... I.E. both upstream sensors at the same time.....so that you will have the same switching charactoristics for both banks of cylinders. Oxygen sensors slow down in their switching charactoristics as they age. So installing just 1 new one....would give you a mismatch in switching speed between the front and rear banks of cylinders.

For tires....I have been VERY happy with Michelin "Harmony" tires. You can find them on www.tirerack.com which is a great place to do research on tires. I bought my Brembo slotted front rotors from them also.

Please do not feel overwelmed by all the things that I have mentioned. You have a 9 year old car....that will do very well for you with some TLC....which ALL cars need in order to last.
I have about 155K miles on my '96 3.8L....and it is doing very well. I plan to keep it for a number of years yet. I enjoy driving it (OK...it is not the sport's car that I would like to have) and feel very confident in taking long trips with it. I take my church youth group on a mission trip each year with it.....and I have no worries about it holding up.

I replaced my catalytic convertors because of a rattle from inside one of them....they were working just fine....but I was trying to nip any problems in the bud.

My pictures of various projects that I have done are at http://community.webshots.com/album/201931518cScpNK

Dorians
08-17-2005, 08:29 AM
P0304 is a misfire on cylinder #4...Front passenger side of engine.
P0306 is a misfire on cylinder #6....Front driver side of engine.

The P0304 is often caused by clogged EGR ports.
There is a port for each cylinder....and they start clogging on the driver side of the engine....closest to the EGR valve. The last ports to clog are cylinders #1 and #4....farthest from the EGR valve..... With the other ports clogged....all the EGR gasses then go to the remaining 1 or 2 open ports.....causing those cylinders to not have enough oxygen.....and the misfire.

The way to tell if it is clogged EGR ports is....ONLY TEMPORARILY disable the EGR system.
You do this by removing....and plugging the vaccum line that goes to the top of the EGR valve.
THIS WILL CAUSE ADDITIONAL FAILURE CODE(s)....for insufficient EGR flow.....which is OK.
I think that code is P0401....but should not cause the CEL light to blink.
With the EGR system temporarily disabled.....take the car for a drive.....and see if you get the blinking CEL or can feel the miss. If you do not....then the problem is with the EGR system.....very likely the EGR ports. If you still get the blinking CEL.....and feel the miss.....then you have another problem. You will need to take a drive....as the EGR system is not active all the time....it opens under certain drive conditions.....and should not be open at idle.

If the EGR ports have not been cleaned......You may want to do it.....and at the same time....remove the fuel rail (after releasing the fuel system pressure at the release valve at the front center of the fuel rail). Remove and clean the spray end of each fuel injector.
You will want to clean as best you can around each injector before removing them....to avoid getting any of that crud down into the engine.
I had a misfire on cylinder #2 that was caused by crud on the spray end of the fuel injectors.....and I noticed a BIG difference after cleaning all 6. I posted a couple of pictures of the crud and the spray end of the injectors. It did NOT clean off with the fuel system cleaners that I added to the tank.
I have seen posts here stating a dealer charge of $150 for a fuel injector cleaning with a machine.....and if it does the job....I would say that it is worth it.

If you have the original spark plugs.....or any plug other than a Motorcraft Double Platinum....you should replace them. Some have tried the Bosche plugs....and had problems. I get to the rear plugs by driving the front up onto ramps......let engine cool as you will be hugging a catalytic convertor.....and slide in under the car.....back far enough that you are looking up the front of the firewall...(in other words....if you went any farther back....you would be looking up at the floor pan)....you will be able to clearly see the rear 3 spark plugs....and reach up to them. Grab the spark plug wire by the boot that is on the plug....and twist it....clockwise and counter clockwise on the plug...to work it loose....then pull.

If you have the original spark plug wires....I would replace those as well.....with a good quality set of wires.

I would also run some fuel system cleaner through....you add it to the gas tank.
I would start with 3 bottles of the "treats up to 12 gallons" Chevron Techron Fuel System Cleaner. I think that the LX came with a 25 gallon gasoline tank. Another good brand...which I use in a "maintenance dose" is Redline Complete Fuel System Cleaner. It has lines on the side of the bottle for how much to add for each 10 gallons of gasoline.....and I add some with each fillup. The Redline has a lubricant that is good for the fuel pump.....injectors.....and intake valves.... You would add the whole bottle to do a periodic cleaning.

Replacing the fuel filter after having run the 3 bottles of Chevron Techron through would be a very good idea. The fuel filter is under the car....in front of the rear, driver side, wheel....on the inside of the frame member. It can be a pain to change on the '96....as 1 side has a plastic clip that you slide out to be able to remove the fuel line....but the front end of the filter has a crome connector that goes over then end of the fuel filter....and you need a plastic removal tool....that you slide up inside the crome connector to release the clips that are inside. You can buy the plastic tool at most auto parts stores....for under $10 for a set of various sizes. They are also used for air conditioning connectors. My set had instructions to use the 3/8" size for the FORD 5/16" fuel line connections. You will want to release the fuel system pressure....at the front center of the fuel rail on the engine before messing with the filter....as the fuel system maintains pressure for quite a while... You do not want a face full of gasoline.

I would also give the vaccum line elbow a look...on the top of the upper intake manifold....driver side.
Mine developed a leak on the inside of the elbow.
Can cause a variety of problems.

Give the air filter a look....if it has some oil (black soot) on it....replace it. If you have the soot on the air filter....I would also clean the MAF (Mass Air Flow) sensor. Use non-residue electronic cleaner. The MAF is in the big plastic part that you remove to get to the air filter.....it is in between the air filter and the engine. You will spray the cleaner in the front hole in the bar while holding the MAF assembly so that the cleaner runs out the hole on the back side of the bar....as I have shown in my pictures.

You will want to make sure that the transmission fluid is changed at LEAST every 30K miles.....21K miles for "severe service". Your '96 requires Mercon rated fluid. Do NOT use Mercon V. I use Mobile 1 ATF, which is a Mercon Rated fluid....and is a synthetic, which takes the heat, and flows better when cold. Better cold flow = smoother shifting in cold weather. The transmissions on mini-vans are weak.....so TLC is needed there.

I added a auxillary transmission cooler.

I also flushed my power steering fluid. The windstar is known for needing that every few years....as it gets hot and breaks down. I used Redline Power Steering fluid....which is a synthetic....and lists the FORD specification number that my owner's manual lists. You do NOT want to add...."Power Steering Fluid" to your windstar power steering resevoir. The owner's manual says to use Ford Power steering fluid....part #xxx or a fluid meeting Ford Specification #xxxx. You will not find the Ford Specification # on any bottle of power steering fluid at the auto parts stores.....
The '96 windstar power steering fluid is a "Type F" Automatic Transmission Fluid. In later years....they switched to a "Mercon" ATF.

I am using Wix oil filters...and Mobil 1 5W-30 motor oil. I change every 3K miles or so.

I have some Bar's stop leak in my antifreeze. The '96 windstar is not so bad for head gaskets..(the '95 was)...as long as you do not overheat the engine....but the lower intake manifold gaskets can leak.....into the cylinders. And the "Timing chain cover"...also called "Front Cover" can have it's gasket develop leaks. The "Front cover" is what the water pump, and the oil pump mount to. It is an EXPENSIVE, very labor intensive repair. The gasket is cheap....but the labor is the problem.
I did not use the Bar's "Original" pelletized stop leak.....I would use the "liquid aluminium" or the other kind that is in liquid or powder form. I would use ONLY Bar's brand.

You have 4 oxygen sensors. 2 "upstream" sensors......1 for the front bank of cylinders....and 1 for the rear bank of cylinders. And 2 "downstream" sensors. 1 after each catalytic convertor... The downstream sensors only monitor the catalyitic convertors to make sure that they are working. The upstream sensors are the ones that the computer uses to adjust the air/fuel mixture. They are NOT a high failure item. I am mentioning them because auto part store counter people often try to sell you oxygen sensors for "lean" codes. Lean codes are most often caused by a vaccum leak. There are codes that will tell you specifically if you have a bad oxygen sensor. So save your money. If you DO replace oxygen sensors.....I would use ONLY Motorcraft brand sensors....and I would replace them in pairs..... I.E. both upstream sensors at the same time.....so that you will have the same switching charactoristics for both banks of cylinders. Oxygen sensors slow down in their switching charactoristics as they age. So installing just 1 new one....would give you a mismatch in switching speed between the front and rear banks of cylinders.

For tires....I have been VERY happy with Michelin "Harmony" tires. You can find them on www.tirerack.com which is a great place to do research on tires. I bought my Brembo slotted front rotors from them also.

Please do not feel overwelmed by all the things that I have mentioned. You have a 9 year old car....that will do very well for you with some TLC....which ALL cars need in order to last.
I have about 155K miles on my '96 3.8L....and it is doing very well. I plan to keep it for a number of years yet. I enjoy driving it (OK...it is not the sport's car that I would like to have) and feel very confident in taking long trips with it. I take my church youth group on a mission trip each year with it.....and I have no worries about it holding up.

I replaced my catalytic convertors because of a rattle from inside one of them....they were working just fine....but I was trying to nip any problems in the bud.

My pictures of various projects that I have done are at http://community.webshots.com/album/201931518cScpNK

Thank you very,very much!
I've never hoped for so many details and tips, and I'm sorry if I didn't reply before but I've lost a family member and I didn't felt like writing or anything else, but as soon as I can, I'm going to start working on the van thanks to all the help that you gave me.

One more time, THANK YOU!

Alan

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