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Any suggestions? My 96 Winstar has an intermittent miss only on cylinder 3. The miss will occure anywhere from 1 or 2 times a minute to nothing for 10 - 15 minutes. Misfire occures when cold (in open loop) and when the engine is at operating temp. Zero evidence of coolant into this cylinder. MIL on. My scanner gives P0303 Misfire Cyl #3. Vacume guage is steady at 21 inches hg, except for a down flick of less than 1 inch on a misfire. With the vacume guage attached, gooseing the engine up to around 2500RPM showed a quick drop to zero, a recovery to about 26 in hg and settle back to 21 in hg.
Swapped plug wires 2 /3 and 4/5. Swapped spark plugs 2/3 and 4/6, then replaecd the year old Bosch w/ a set of Autolite Platinum's.
Checked the coil pack. Resistance was out of spec. The primary coil for 1/5 was low, .06 ohms and the other coils were high about 2.5 ohms. Range is .3 to 1 ohm. Replaced it. No change. The new coil pack was with-in specs listed in the Haynes manual for the primary and secondary coils.
EGR ports are clean! I cleaned them last year when I replaced the intake manifold gaskets. (had a AF leak into the #1 intake valve). I checked them again to verify they were all clear.
Disconnected the EGR to see if a possible block in the passage. No difference.
Swapped fuel injectors #3 with #2. Problem stays with #3. Checked the wiring to #3 injector. Near 0 resistance and no deflections when I wiggle the connections, including the plug that passes from the main harness to the Intake wiring harness. This was checked from the harness pin at the PCM to the injector plug.
Compression test was somewhat high on all cyllinders. Minimum is 101 psi. All 6 tested between 200 and 215 on 4 cranks.
None of the changes listed above altered the misfire.

Except for the PCM, I don't know of anything that would affect just 1 cylinder.
I would expect a sticking valve to show a much larger down flick on the vacume guage.

Mark
 

maypo7957 wrote:

Any suggestions? My 96 Winstar has an intermittent miss only on cylinder 3. The miss will occure anywhere from 1 or 2 times a minute to nothing for 10 - 15 minutes. Misfire occures when cold (in open loop) and when the engine is at operating temp. Zero evidence of coolant into this cylinder. MIL on. My scanner gives P0303 Misfire Cyl #3. Vacume guage is steady at 21 inches hg, except for a down flick of less than 1 inch on a misfire. With the vacume guage attached, gooseing the engine up to around 2500RPM showed a quick drop to zero, a recovery to about 26 in hg and settle back to 21 in hg.
Swapped plug wires 2 /3 and 4/5. Swapped spark plugs 2/3 and 4/6, then replaecd the year old Bosch w/ a set of Autolite Platinum's.
Checked the coil pack. Resistance was out of spec. The primary coil for 1/5 was low, .06 ohms and the other coils were high about 2.5 ohms. Range is .3 to 1 ohm. Replaced it. No change. The new coil pack was with-in specs listed in the Haynes manual for the primary and secondary coils.
EGR ports are clean! I cleaned them last year when I replaced the intake manifold gaskets. (had a AF leak into the #1 intake valve). I checked them again to verify they were all clear.
Disconnected the EGR to see if a possible block in the passage. No difference.
Swapped fuel injectors #3 with #2. Problem stays with #3. Checked the wiring to #3 injector. Near 0 resistance and no deflections when I wiggle the connections, including the plug that passes from the main harness to the Intake wiring harness. This was checked from the harness pin at the PCM to the injector plug.
Compression test was somewhat high on all cyllinders. Minimum is 101 psi. All 6 tested between 200 and 215 on 4 cranks.
None of the changes listed above altered the misfire.

Except for the PCM, I don't know of anything that would affect just 1 cylinder.
I would expect a sticking valve to show a much larger down flick on the vacume guage.

Mark

richardward42 wrote:

maypo7957 wrote:

Any suggestions? My 96 Winstar has an intermittent miss only on cylinder 3. The miss will occure anywhere from 1 or 2 times a minute to nothing for 10 - 15 minutes. Misfire occures when cold (in open loop) and when the engine is at operating temp. Zero evidence of coolant into this cylinder. MIL on. My scanner gives P0303 Misfire Cyl #3. Vacume guage is steady at 21 inches hg, except for a down flick of less than 1 inch on a misfire. With the vacume guage attached, gooseing the engine up to around 2500RPM showed a quick drop to zero, a recovery to about 26 in hg and settle back to 21 in hg.
Swapped plug wires 2 /3 and 4/5. Swapped spark plugs 2/3 and 4/6, then replaecd the year old Bosch w/ a set of Autolite Platinum's.
Checked the coil pack. Resistance was out of spec. The primary coil for 1/5 was low, .06 ohms and the other coils were high about 2.5 ohms. Range is .3 to 1 ohm. Replaced it. No change. The new coil pack was with-in specs listed in the Haynes manual for the primary and secondary coils.
EGR ports are clean! I cleaned them last year when I replaced the intake manifold gaskets. (had a AF leak into the #1 intake valve). I checked them again to verify they were all clear.
Disconnected the EGR to see if a possible block in the passage. No difference.
Swapped fuel injectors #3 with #2. Problem stays with #3. Checked the wiring to #3 injector. Near 0 resistance and no deflections when I wiggle the connections, including the plug that passes from the main harness to the Intake wiring harness. This was checked from the harness pin at the PCM to the injector plug.
Compression test was somewhat high on all cyllinders. Minimum is 101 psi. All 6 tested between 200 and 215 on 4 cranks.
None of the changes listed above altered the misfire.

Except for the PCM, I don't know of anything that would affect just 1 cylinder.
I would expect a sticking valve to show a much larger down flick on the vacume guage.

Mark

tommy m wrote:

richardward42 wrote:

maypo7957 wrote:

Any suggestions? My 96 Winstar has an intermittent miss only on cylinder 3. The miss will occure anywhere from 1 or 2 times a minute to nothing for 10 - 15 minutes. Misfire occures when cold (in open loop) and when the engine is at operating temp. Zero evidence of coolant into this cylinder. MIL on. My scanner gives P0303 Misfire Cyl #3. Vacume guage is steady at 21 inches hg, except for a down flick of less than 1 inch on a misfire. With the vacume guage attached, gooseing the engine up to around 2500RPM showed a quick drop to zero, a recovery to about 26 in hg and settle back to 21 in hg.
Swapped plug wires 2 /3 and 4/5. Swapped spark plugs 2/3 and 4/6, then replaecd the year old Bosch w/ a set of Autolite Platinum's.
Checked the coil pack. Resistance was out of spec. The primary coil for 1/5 was low, .06 ohms and the other coils were high about 2.5 ohms. Range is .3 to 1 ohm. Replaced it. No change. The new coil pack was with-in specs listed in the Haynes manual for the primary and secondary coils.
EGR ports are clean! I cleaned them last year when I replaced the intake manifold gaskets. (had a AF leak into the #1 intake valve). I checked them again to verify they were all clear.
Disconnected the EGR to see if a possible block in the passage. No difference.
Swapped fuel injectors #3 with #2. Problem stays with #3. Checked the wiring to #3 injector. Near 0 resistance and no deflections when I wiggle the connections, including the plug that passes from the main harness to the Intake wiring harness. This was checked from the harness pin at the PCM to the injector plug.
Compression test was somewhat high on all cyllinders. Minimum is 101 psi. All 6 tested between 200 and 215 on 4 cranks.
None of the changes listed above altered the misfire.

Except for the PCM, I don't know of anything that would affect just 1 cylinder.
I would expect a sticking valve to show a much larger down flick on the vacume guage.

Mark

thy i qt of reslon oil - yellow contaner -auto zone sales it 5 bucks let it run and this stuff will stop valves from sticking - i dont beleave in a mecanic in a can but this stuff works//// if its the valves??????????????????????????

From the reading, it's not clear if you replaced all the spark plug wires with a new set.  

We share the same problem on the same vehicle. I have done everything as well. I just changed the fuel pump in case of cavitation. No change. It is cylinder #3./ It did once or a few times change to other cylinders however it seems to be with #3. I have been thinking of injector timing??? However it may be carbon on the piston, I sprayed the cylinders with carbon cleaner and it will sit over night. I will let you know if it helps.
Dave  

Spray carb cleaner around the #3 intake runner if it starts to miss the gasket could be bad.this would cause a lean miss just on one cylinder. Also just a resistance test can cost you money. the temperature of an electrical device can change its resistance greatly try a lab scope if you have acess.  

That would have to be the lower intake, however there is somewhat of a pattern. The van was driven 150KM no MISFIRE. Then shut off, restarted put into gear and started to Misfire. It can then be shut off and no miss for some time? This is the regular occurence? At times it can run for hours no miss. I have ordered a Labscope so time will tell. No coolant loss either. Fuel pressure steady at 30PSI. This one I have been working on for a few months when I can get the van. I'll keep you posted.
Dave  

I have found the problem, it was cavitation so to speak. The pulsatr in the fuel tank had sprung a leak. Replaced pulsator with a piece of rubber fuel hose and it is fixed. The air was going to cylinder #3 on the rail. That is your problem too.
Dave  

Im glad to see you have found the problem. I never would have guessed that.  

Hey Mark,

I am not a mechanic but I have a 96 Windstar that occasionally misses mostly on cylynder #1 when I start it..  I had my mechanic clean the EGR ports and fix a vaccuum leak.  Still I get the flashing engine light on cold starts especially after it sits for over a day.  This may sound strange and you will think I am nuts but I discovered when it happens, I shut the car off and restart it.  Problem gone.  Also when I start the car I make sure that the engine turns over real good when I start it instead of just pulsing the starter switch.  It is like resetting a computer and it might be doing just that.  It works but the mechanic says It will not be like this forever.  So far almost 10,000 miles later it is still running good as long as I do these things.

Ed


 

I have the same problem with my windstar 96 #3 missfire and it get rought at stop sign and the oil light flickers could that be the same problem the oilpump strainer was cleaned and replace the oil pump is good if I keep my foot an the gas it runs fine.  

1996 Ford wind star 3.8 V-6 with 100,000.
I First noticed the Misfire problem 2 months after the van was  purchased,

Replaced all 6 plugs with Motorcraft wires and new coil pack.
2 new o 2 sensor's per auto zones recommendations.
Cleaned and desludged the upper intake manifold ports and replaced the upper gaskets.Checked lower intake manifold gaskets for leaks with carb cleaner.
New air filter and PVC and replaced with working used vacuum diaphragms that open and close the upper intake manifold lower valves.check all vacuum hoses and replaced three with new.

Problem is still there but is less .

Great on cold starts but after engine reaches operating temperature and is warm to hot, the check engine light begins to flash and a Miss fire type of performance is noticed.There is NO Coolant or fluid loss, no tail pipe steam or signs of a head gasket problem.
I have noticed that the number two rear bank cylinder plug seems to foul up with what appears to be oil or black mass, and a rear bank running lean error code with miss fire.

any suggestions on what i might be over looking or should try next would be appreciated.

Thanks  

Problem solved after reading fords data in sensor replacement.

I disconnected both the positive and negativity battery cables from the battery for
10 minutes and restarted and drove the car at various speeds per fords recommendations.

The engine runs smoother then it ever has with excellent pick up.

The sensor displacements reprogram themselves in learning the proper air and fuel mixtures.