1999 Ford Ranger chugging in OD

[scaryfast]

hello,
I am new to this site and i have a few questions about my 99 Ford Ranger 4.0.
I was going down the highway the other day and i was passing someone and the truck kicked down out of overdrive just fine, but when it kicked back into OD it started stuttering at lower RPM's in OD. It was low on gas but not empty. I then exited the highway and it was running like crap at idle speeds and when i would accelerate normally. If i really got on it, it was fine.

So i went home and changed the plugs and all 3 passenger side plugs had the tips burnt off them. I put new plugs in it and the idle and acceleration was a lot better but it still hesitates on the highway in overdrive.

If any of you guys can help me here i would greatly appreciate it.

 

[Wicked_Sludge]

when was the last time it got a fuel filter? any check engine lights?

 

[scaryfast]

nope no check engine lights

I am not sure as to the fuel filter, i have only had the truck for about 30,000 miles. Its got 171,000 miles on it. It also seems to be gradually getting worse again.

 

[Wicked_Sludge]

id start with a fuel filter since it has unknown mileage on it anyway. if there was sediment in the bottom of your tank, it could have been stired up and ingested when you passed on the highway.

might as well check your air filter while your at it.

 

[snake]

If it is trying to die at idle it could be the transmission torque converter not unlocking.

If you are certain it is an engine performance problem try running an injector cleaner through the system. I prefer 44K available only at stealerships and oil change places- not at any parts store. A can is about $20 but the stuff works...

BTW what brand of plugs did you use? Some brands don't run right, I always use motorcraft stuff.

 

[scaryfast]

i already changed the air filter to a k&n, that was 5,000 miles ago

And my buddy works at a shop and got me some of that 44k stuff and it didnt make any difference, the idle is fine now, it does it the worst in overdrive. Accelerating is fine until i get into upper gears. Like i said, it does it the worst in overdrive, if i have my foot on the pedal lightly in overdrive and im doing 70-72 and then give it a little gas, not a ton but a little harder on the pedal, it jolts the truck like its quickly cutting out.

Now my buddy ran a computer tester on it underneath the steering wheel and nothing came up except for it was misfiring.

Im just looking at where to start here, im kinda confused

 

[eric17]

my truck was doing the exact same thing only at 45 and above though, if i floored it, it would downshift and be fine but under a light load it would miss and run rough, i put in a new fuel filter, took the throttle body off and cleaned it all it was very dirty, also i found a pin hole in a vac line to a sensor on the intake manifold, something to do with the gas pressure, anyway after doing that i drove it and it was like a totally different truck. i tested my compression, my vaccum and fuel pressure and everything was good even with the old fiter im assuming it was something to do with the air leak, the mass amount of grit in the tb or a combination of both, chances are its something small, ive got 253k on the ol 4.0 you have along way to go!

 

[scaryfast]

Eric17,
thats exactly what its doing, it downshifts fine, but when the engine is under a little strain its cuts out

 

[chittybangbang]

i already changed the air filter to a k&n, that was 5,000 miles ago

And my buddy works at a shop and got me some of that 44k stuff and it didnt make any difference, the idle is fine now, it does it the worst in overdrive. Accelerating is fine until i get into upper gears. Like i said, it does it the worst in overdrive, if i have my foot on the pedal lightly in overdrive and im doing 70-72 and then give it a little gas, not a ton but a little harder on the pedal, it jolts the truck like its quickly cutting out.

Now my buddy ran a computer tester on it underneath the steering wheel and nothing came up except for it was misfiring.

Im just looking at where to start here, im kinda confused

Did this all start to happen after the k&n filter was installed?

 

[snake]

I see where you're going with this- MAF sensor greased over from the oil, good point.

Also could be the sparkplug wires, they will break down under load (OD) first before showing up and lower speeds and lighter loads.

 

[scaryfast]

so i am thinking i will start with a tune up and a new fuel filter, relatively cheap and might just fix my problem.

Anyone know a good performance exhaust to use on the 4.0L, i want a good tone, i dont want it to sound like a rice rocket at all.

Thanks

 

[eric17]

have you fixed the problem yet? im pretty sure the little pin hole in the vac line was my problem, well i duno i did a few things at once but the fuel pressure was about 5psi higher than before it was fixed, after doing that and pulling the plugs to have a look, also used another sensor i had from a different motor ill find out which one it was, had a gas line or something going to it we though might be bad. so far its running good