Well I have a good one this time. Well at least for me anyway. I just bought my 2000 Ranger about four months ago and havent had much for issues.
Well I was driving at about 45 mph the other day and noticed a miss and then it downshifted and really it started to missfire. I figured maybe plugs or wires. "I always like to change these on vehicles that are new to me". I installed new plugs (gapped at .044) and new wires. Changed the wires one at a time to make sure I didn't screw that up. Also checked the Clymers service manual to make sure they were correct to start with. well the plugs were way shot. They had burned way out of spec. This made me think that I had the problem solved. Drove the truck for a few days with no issue and then it did it again. Oh yeah I failed to mention the OBD2 code of PO305. Missfire on hole number 5. Checked both the plug and wire to make sure they are ok. They both check out fine with the multi-meter.
Have been surfing the forums to see if this is an issue that crops up on some fords. Havent found much and not much that has helped.
I have cleaned the MAF. Installed a new air filter. Checked for any vacuum leaks there are no leaks.
I just had an issue with the battery cables being corroded and not making good contact. I have cleaned that posts and installed new terminal ends on the cables. Also checked the ground connections on the truck. I was thinkin that maybe a bad ground could be causing an issue, but they are all ok.
Any body have any questions or any ideas let me know. I have been working on cars and trucks for a long time and this one is pissin me off. Thanks Brian

 

Oh yeah. I have also changed the coil and that made the problem worse for awhile. After about two days driving back and forth to work the issue went away. It started missing a few days later and then it came out of it while I was driving at about 40 mph. Now it comes and goes and I am totally confused. Any help would be great. Thanks Brian

 

Grab another plug and change # 5.Even a used one.
I've had plugs that were new and looked fine but were bad.


Edit:
I have noticed on the forums here lately quite a few have been having head gasket issues noted by misfires on cyl 5 and/or 6.
Noticed any coolant disappearing lately ?

 

Thats not a bad idea. I will try that as soon as I can.

 

Brian, when you change plug #5 look closely at the threads
to see if they're rusty.
I'm thinking a faulty lower intake gasket, letting coolant into
the cylinder and causing the misfire.
When it starts missing again, try releasing the radiator cap
pressure and see if the misfire stops......

 

I am having the exact same issues with cyl. #3. P0303 code too. Comes and goes, regardless of whether or not the CEL is lit, it has the stumble, though sometimes it smooths out.

Have you tried anything more so far? I did have a collapsed radiator hose on occasion. I'll keep you posted once I get to diagnosis. Have you looked under the hood to see if your top hose was collapsed? Check it after an hour or so after you stop and the motor once it got to operating temp.

My coolant is fine, my oil looks good too.

 

Collapsed radiator hose means the water pump is going out.

 

RedRanger, I had not heard that anywhere. I have heard radiator cap and (I hope not) head gasket.

 

Well I checked the plug in hole 5. The plug looks good and I didnt see any rust or fowling. I did switch with another plug and went for a ride. No change. When I started her up she was running a little rough but after about a mile it smoothed out. By the time I got to work it started missing again. I have checked the hoses and the coolant level is good. Ran her up on the lift and checked the cats out they seem to be ok as well. Still confused. I even tried the old kick the tire trick but that just made me feel a little better..

 

i disagree, its something more simple. such as the radiator cap.

 

look into your injectors i had about 3 rangers come into work saying they changed the plugs and wires. the miss was still there being that i had this problem on my truck i always look at injectors and that usually seems to be the issue

 

What is the best way check the injectors. Can I do this with my scope?

 

switch #5 to #3...if you get #3 misfire its injector

 

I will try that. Let you know what happens. Thanks Brian

 

Have you ever tried to do that? The only way I can see doing that is by pulling the intake and then I can get at them. Not sure if I want to do that though, if I have to then so be it. Any better way to check them? Well maybe not better but easier... thanks Brian

 

never done it on a 3.0. Did it on a GM 5.3 and all it was was

1. Disconnect fuel rail
2. unplug injector
3. Remove retainer clip
4. Pull injector out

 

i will say its kinda a pain on a 3.0 you can even stick a large screwdriver on the injectors while you have it running or a stethoscope and see if you can hear the injectors working.

 

Yeah but the intake on the thing goes over the 4,5,6 injectors. I can see the #4 injector and can barely see #5 injector. Cant see six at all but it has to be there.

 

Thats kinda what I was thinkin.

 

if i was closer id come over and help ya man sorry. its a pain to get to 456 with a screwdriver or stethoscope but it can be done trust me haha

 

I would let you help me to. I will have to pick up a scope and then see if I can hit it.

 

ah damn...not as easy then :(

 

Well I went to sears and picked up a scope so I could listen to the injectors. Got home and started out listening to the 123 injectors. Just to get a base line. Went to the 456 injectors and they all sound the same to me. The only thing I heard that might be a little weird is a real light tick on #1. Thinkin that may be a stuck lifter or something on that line, but that has nothing to do with the miss...So whats next? Brian

 

Brian, turn the radiator cap to release the pressure, leave it loose
and drive it that way. See if the misfire continues. If the misfire
is 'fixed' with a loose radiator cap, then the lower intake gasket is faulty.......

 

Well I will give this a shot. Let you know what I find out. Just had a hell of a snow. Got about 4 inches yesterday and it all melted today. Caused some pretty ****ty roads for a bit though.