well ive fixed the misfire problem, the problem is due to a fouling plug, unfortunatly my engine seems to foul plugs often, ive looked for the obvouis oil leakage, coolant in the combustion chamber, or maybe a sticking valve, does anybody have or had this problem, if so let me know thanks in advance.

How many miles are on the engine? You might have a piston ring problem. Blow by in that cylinder might be causing your fouling problem. Only a guess though...

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Sgtsandman's Work in Progress
2011 Ranger XLT, 4X4, 4 door Super Cab. 4.0L, 5 Speed M50D-R1HD, 3.73:1, 8.8" open differential, Jason Pace cap
2019 Ford Ranger STX FX4, Super Crew, 2.3L Ecoboost, 10 speed automatic, 3.73:1 with rear locker, Leer 100XR cap

the engine is newly rebuilt with only 50,000 or so on it, no signs of piston rings failure or wear, plugs come out clean, tad on the lean side but i believe i have fixed that with decarboing the engine with seafoam deep creep and berryman throttle body spray, right now it looks like a hunt to find the phantom problem.

I wonder if an injector is running rich then. Have you done anything to clean the fuel system? If the fuel is too rich, it can cause a fouling problem due to incomplete combustion.

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Sgtsandman's Work in Progress
2011 Ranger XLT, 4X4, 4 door Super Cab. 4.0L, 5 Speed M50D-R1HD, 3.73:1, 8.8" open differential, Jason Pace cap
2019 Ford Ranger STX FX4, Super Crew, 2.3L Ecoboost, 10 speed automatic, 3.73:1 with rear locker, Leer 100XR cap

sometimes coil pack can cause one plug to misfire on cylinder, might change coil pack. had same problem. it fixed the problem

I have the exact problem. My truck is in the shop now and the people want to replace the plugs saying they are bad and thats my problem but i know that isnt it bc i have changed my plugs like 4 times now so something is causing them to go bad. If i find out whats wrong i will let u know and if u find out whats wrong let me know. thanks.

Make sure that the wires are ran correctly and that the firing order in correct. Next make sure that the wires arent touching. If your still fouling plugs it could be from too much fuel or a possible oil leak from the valve seals. Sometimes fuel injectors can go lazy and dump too much fuel. Is it every plug or just one or two?

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89 Ranger- front and rear bagd on drop ibeams and custom 2 link.

85 Ranger- 4x4 31" tires. Soon to be V8 swapped with D35s and 8.8.

mine is just one plug. cyclinder 4.

Not to scare you but I chased this same problem around for a while, changed plugs and wires and coil pack and kept getting either cylinder 4 or 6 misfire code. I finally broke down and paid Ford the $125 to hook it up to their computer to identify what the problem was. They had it all day which concerned me and came back to say I had stuck vlv's in both the #4 & 6 cylinders. They wanted to change the engine for $5200! I took it home, changed both heads (one was cracked) and it runs like a top. The machine shop said the 3.0 & 4.0 engines have a history of vlv seat issues which will cause a misfire. Turned out to be my problem and cost me less than $1000 to do it myself (2 new heads with vlv's installed $450 from Alabama Cylinder Heads.com). Changed the water pump for S&G's while I was at it. I could have saved the one head and had the machine shop work it but the price difference between that and new led me to by the two new heads altogether. Glad I did, happy now!

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2000, 4x4, 4.0 Ext cab

I think it has something to do with my exhaust vavles or head too. Only problem is tring to find a mechanic that that thinks that also and will do the work, b/c i dont know how to do that.

I have had this problem too. Mine was actually a spark plug that was about to break completely if i kept driving it. What I did was changed the plugs and wires to Bosch and it is recommended to get a fuel injector flush but not mandatory. Now, no more misfire .

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Sunny
2002 Ford Ranger Edge Flex Fuel 2wd
LED Crazy!
Complete Pioneer Audio setup
5000k HID Projector retrofit and 3000k Fogs
Achilles Desert Hawk 255/45/20 with 20'' rims
Looking for a professional retrofitter? Send me a message!

Well if it is a vlv issue you can get a compression kit fairly cheap to verify if you do in fact have a valve or piston ring issue. Of course this still does nothing toward the fix other than point you in the right direction. How mechanically inclined are you? Reason I ask is, I've never done heads either and I did mine myself. I made a few mistakes which cost me an extra $100 in gaskets and 3-4 hours of extra work but it runs better now than it has in a few years.

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2000, 4x4, 4.0 Ext cab

Jordan, I kept cracking the #4 plug and couldn't figure out why. As it all turned out I bet the cracked head was the reason I kept cracking the porcelain insulator on the plug in that one cylinder. I'm not an expert but I'll bet money on this.

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2000, 4x4, 4.0 Ext cab

I had this exact problemi replaced plug after plug and it kept on fouling in a few months.. honestly I hate to sound like a salesman but I changed the oil and dumped in that z max stuff... no more miss I have done countless oil changes and added z max every 6000 miles since then

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2000 ranger 4.0v6 4x4 ext. Cab with a cap
Mods....
http://www.fordrangerforum.com/proje...start-now.html

how muc ouldyou guy pay for all of ur exhaust vavles to be changed?