I recently bought a '02 Ranger 4x4 with the 4.0L V6 and an automatic trans, besides the small issue where the passenger window switch doesnt go up I'm lovin the truck. It's my daily driver so I need it running in tip-top shape as I have a 70 mile commute for work Monday - Friday. The issue I cant live with or understand for that matter is this one I have been noticing recently.

When I am driving sometimes when I am going up a hill or something and I'm at a certain speed (i.e. 48mph @ 1700-1800rpms) it will thump under power at least until I left off of it and hit the pedal in a bit more. It seems like as soon as it goes into a lower gear (higher RPMs) its fine. It reminds me of a motorcycle when you come up to a stop sign or something and forget to shift down, when you start back up it thumps until you grab the clutch and shift a gear or two down.

I also notice it at other speeds like around 58mph @ ~1800rpms and somewhere in the 60's. It's not every time, but then again I cant have it become everytime nor can I have this happening when I'm going up a hill and just so happen to be going around 50mph. I really love the truck, but now I am having second thoughts that I should have just got a 5 speed.

Hopefully its just something rather simple that I could take it into a transmission shop or something and they do a "tune up" or whatever it is that transmissions shops do to it. I was told by the previous owner when he bought it with 58k miles (it now has just shy of 70k) it was a ford certified vehicle and that they have to replace alot of things and do alot of stuff to the vehicle to have it be "certified" so he told me the trans fluid was done, which when I look at the dipstick it looks pretty red still so I believe him because everything else that I can verify (brakes, tires, etc.) looks to be in great shape.


Any thoughts or suggestions?

 

Spark Plugs? Fuel Filter? Spark Plug Wires? Check all of those.

You could have the tranny flushed again, not like it will hurt anything but I wonder if they dropped the pan and changed the filter too. I would make sure that is done.

 

but could plugs/wires do it just at specific speeds and rpms?

I'll get my neighbor to bring it into his shop sometime soon.

 

I took it as it did it under load right?

If so it could be any of those.

 

ahh, ok. Yea it does seem like it doesnt it occasionally under load. I wasnt doubting you, I just wanted to know how... but I got it now. I'll call my neighbor up and see if he could put it in sometime this week.

Actually it's probably just easier to do the plugs and wires myself if they are easy enough to do. I'm sure it's cheaper that way, but the fuel filter I have to remember what I did wrong last time, I know I got the little tool to take it off, but I was also under the car in a pool of gasoline while yelling inside for someone to call the neighbor hahahahaaa

What plugs & wires would you reccommened and also do I need to take off any wheels or get anything special to do the plugs & wires on the 4.0 SOHC?

 

Motorcraft plugs and wires. Autolite also makes great plugs. The ford motors love both those.

Best way to change plugs is through the fender. No 'special' tools really required.

 

so through the fenders means I have to jack up the front and take a tire off at a time?

No gapping required on these plugs if I just go to a Walmart or Advanced Auto and pick up motorcraft plugs to fit an '02 Ranger 4.0L V6? I've never seen wires at Walmart so I assume Advanced Auto would be best for that when I go to get the fuel filter. Since the filter is the easiest I think I'm gonna start with that (dont I need to disconnect the battery ) then move on to the plugs.

 

you wont need to disconnect the battery for any of it.

the fuel filter does not require tools, pinch the clip with your fingers, shove it in and pull it off. watch out for the fuel!! lol

i would check the gap, its important to make sure its right. i believe the gap required is posted on the core support under the hood.

and yes it would be wise to remove the tire. i dont really have that issue though. lol

 

do you have a K&N filter? or is the filter a motorcraft filter? i had the same problem with my dads 04, and the aftermarket filter was not sealing onto the air box lid properly, causing MAF voltage spikes which intern would cause the surging.

i would get a motorcraft air filter and make sure the lid is sealing correctly around the filter

 

ahh, yea I just added a K&N filter within a week of buying the truck. So I can definately check that out by buying another paper filter on my way home today. What about FRAM filters at Wally world, or should I just go somewhere else to get the motorcraft one?

So if it is actually the air filter is my K&N useless, or can I seal it better? I rememebr it was hard to get the lid closed when I first put in the filter.

 

Motorcraft all the way. I am not a Fram fan. I think Justin would agree too.

Motorcraft makes good stuff and its what your truck comes with originally.

 

alright then, will do. (Can I pick up Motorcraft at Advance Auto or AutoZone... or where besides a dealer?)


Thanks guys for the help, it looks like I'll go through one item at a time and do these tonight. First being the air filter and then the fuel filter, if neither of those fix the problem I'll go ahead and do the plug and wire change.

I'm glad noone said so far that its tranny, it lets me breathe a sigh of relief because these changes are all alot cheaper and the transmission shifts smoothly and all, it just gets in these little ruts every once in awhile.

 

yes both of those places should have them i am pretty sure.

 

I bet its the voltage spike, we had a write up about this a while back. Thats what caused my problem. Ask Justin

 

Cool, thanks all for the advice, I'm gonna go with the air filter first because that seems most logical since I did have a hard time getting it in. Also I de-snorkeled the airbox, would this cause any ill effects? Should I take off the MAF box and clean anything?

 

I changed the K&N out for a purolator as the place(s) I went to didn't have Motorcraft nor did I want to get FRAM after what you guys said. So between doing that and the fuel filter I just took it out for a 10 minute test drive and didn't feel a thing. Tomorrow's commute to work will be a test though, so I hope all is fixed. I also picked up a set of autolite wires and platinum plugs and I gapped them to .065, but I guess I wont be putting them on right now. My truck is just shy of 70k miles, so maybe I'll wait til a benchmark to put them on and at least I'll have them. Can the wires degrade by just leaving them in the box?

Is there a chance I can (should) use my K&N, just put it on differently or something?

UPDATE: So on my commute to work I felt it only in a couple spots, but it was like 80% better. I looked on my bank card records to see where I may have picked up some bad gas, but I'm not sure, but I still think that had something to do with it. I will be changing the wires and plugs this weekend because I still feel it, but its seldom. How about getting to the plugs, from others who have? Will I need a 12" extenter for my ratchet? Will it be a pretty simple task if I jack up the front and take off both tires? I'm assuming for simplicity sake I should do one at a time because I dont want to mix anything up.

 

It's great now!!


I spent a few hours last night (first time) changing the plugs and wires myself and I took the long way to work today, which definately gave the truck a run for its money and no problems whatsoever. I think looking back that it was a combination of things, potentially a bad shot of gas & the plugs/wires needed to be changed.

When I was changing out the plugs it looks like the last time they used Autolite Platinums, but 2 (the seemingly hardest) plugs were Motorcraft plugs and definately showed more wear, whereas the Autolites had very little wrong with them. So the plugs may have been changed about 13k miles ago, BUT I still think those Motorcraft plugs were the originals and there was somewhere a worn wire. Hah.. I also found out that my govenor kicks in at 92mph, but now that I think about it I read that on this forum before, but hey I got to feel it today.

 

sounds good man. yeah i bet they were lazy and didnt change the harder ones. its not really that hard to change them once you know to go through the fender well.