question here. i took my truck to an autozone dealer to have it checked. while doing the test, the guy pulled out a code that said, cylinder #6 its not working. could it be something serious?. i already replaced spark plugs , wires, a sensor, fuel filter. i dont know whatelse to do. oh almost forgot it. i replaced the fuel injector not long time ago. because its resistance was different to the other 5 injectors . i already checked the coil and there is spark at the spark plug #6.

 

Welcome to FTE.
You've been busy on this one. Post up All trouble code Number clues & which engine/tranny/cab your 99 Ranger has.
Did the problem come about suddenly, after some event???
Seeing as how you have a code for #6 cyl & you say you have spark to it & have Recently replaced the plugs & wires, did the problem come about After #6 got its new plug & wire???? Pull #6 plug & check for damage/hairline cracks, or chips to its internal & external ceramics. Check #6 plug wire end to end resistance, it should be something like 1K ohm/inch of length, 30K ohms max, no matter the length.
Seeing as how #6 cyl also has had its fuel injector replaced, have you checked its electrical connector to make sure its pins/sockets are ok, the connector is locked in place & has 12 volts to it at KOEO???
Have you checked #6 injector resistance????
Does #6 injector click & does that click sound like the other injectors????
When its missing, can you hear any mechanical noise from that cyl
Some thoughts for consideration, let us know what you find.

 

thanks for get back to me. here is the story. like 2 or 3 weeks ago the truck was misfiring when i tried to start it up and i noticed some lack of power. one day i barely arrived at my work because of that, so next day i went to Autozone to start replacing parts. as they suggested me, i replaced spark plug wires, a sensor which is located between exhaust manifold and intake manifold (MAF). suddenly when i was about to leave the store, boom!! popping noise coming out of the exhaust and didnt start, finally after many attempts i had it started and go back home. i was really upset about it so i dissasembled the whole intake system, manifold, wires, hoses, and started replacing all 6 spark plugs (Motorcraft platinum), a gasket that goes into intake manifold. i disconnected all injectors and meter their resistance to make sure were ok, and i found #6 cylinder injector had a little bit more resistance so i replaced it. put it all back together, but since then i dont hear misfiring sound anymore but i sense a lack pf power. a few days ago i took it to get it checked and they pulled out a code saying #6 cylinder not working, besides bad EGR valve and oxigen sensor. i am not a newbie, i know EGR valve and oxigen sensor dont have to do with number 6 cylinder not working, so this weekend i will pull the manifold out again to do what you just told me and will surely let you know the results. oh by the way my truck is a XLT 3.0 V6 `99 with 180k miles on it. lol at your nickname, are you a police officer or what?. thanks in advance.

 

OK, that's some good feedback. Good idea to have used the Motorcraft spark plugs.
Is your 3.0L a flex fuel model, if so, you need to use the specified heat range spark plugs & right part number fuel injectors????
Post All trouble code Numbers you had, as they can offer up good trouble shooting clues. BTW, is the CEL still lit???? It should have been blinking if you had a cylinder misfire. Driving it with a misfire will cause the cat converter to over heat & if the over heat is bad enough, it can cause its innards to melt down & restrict the exhaust & that can cause a loss of power from excessive exhaust back pressure, all a vicious circle, so you may have more than one problem.
To check for a restricted exhaust, view scenario 14 here http://www.secondchancegarage.com/public/186.cfm & use your vacuum gauge to look for this kind of response from it that indicates excessive back pressure & maybe a clogged cat converter, collapsed muffler innards, or kinked exhaust pipe.
Have the computer scanned again & post up All code Numbers.
Stop throwing parts at the problem. Only replace parts that trouble shooting finds are bad.
Let us know how your trouble shooting goes.

 

You say you have a lack of power, its possible that #6 is dead, like its got a burnt out valve, or bent push rod and not firing at all. To test, while at idle, hold a piece of paper next to the end of the exhaust pipe. If it sucks the paper into the pipe, you have a bad valve, if it just pulls the paper up against the pipe now and then, its misfiring.

 

ok sorry for the late response, i will try it today and let you know. last weekend i disassembled the whole fuel injection system, and i didnt find anything wrong.