I have a 2002 F250 Lariat with the 7.3L, 70,500 miles, Auto, Exhaust and intake...Just changed the oil 500 miles ago and since I have owned it I have not done any other maintenance such as fuel filter, glow plugs...etc


Ok So just recently my truck has been ideling a litte rough....some times you can see the RPM gauge jump up and down slightly(+/-100 rpm) and I can definatly feel it too. Also it seems to just slightly buck a little between 30 mph and 60 mph(no rpm variation during the bucking). Is this a possible indication of a CPS going out?

 

Ok....I have done some searching but can not find anything that helps me out....I really would like to see if anyone knows whats wrong.

When I say rough idle I mean a slight miss and rpm variation..maybe like 100 rpm or so. This condition only seems to show up after a drive long or short and I notice it when I put it in park, thats when I have noticed a rough idle, when its doing this I have hit the throttle and it has good response and seems to run fine/smoother at high rpms. My instinct is telling me that it could be the cps, or an old clogged fuel filter(I have not changed it yet since I bought the truck 6,000 miles ago /6 months).

I also get a slight stutter/bucking at lower speeds when the truck is not under a load like acceration or going up a hill....its not enough to show on the rpm gauge and barely notice any change on the speedo but I can definatly feel it sometimes. Again my instinct is telling me the CPS....cause thats what seems to be the cause of most of the symptom's that I am experiancing.

What do you guys gather from this? any suggestions? I am most definatly gonna change the fuel filter this up comeing weekend so maybe that will cure my problems.

Also FWIW: My truck runs very strong it seems to me, I have no chip or tuner but I still get a kick when I punch the throttle. Also my truck doesnt smoke much so I kinda ruled out any injector problems but should I considder the harness under the valve covers? I hope thats no the case but its possible. Also would too much oil cause any symptoms like I am describing? my oil is a little high, not much but enough to tell when I check the dip-stick.

 

how does it start when its up to operating temp? how many secs does it spin over before it hits?

 

on a cold morning(20-40 degrees) it might take between 2 and 3 seconds. Right now with temps being around 50-60 degrees it is taking between 1 and 2 seconds, but some times after I have gone somewhere and come back to start it (warmed up) it can take 3-4 seconds and sometimes it will "hit" and then it will die as soon as I let off the key....but then it will start right up when I try again. So I would say when its at operating temp it can take anywhere between 2 and 4 seconds......and once in a while it will crank right up in about 1 second.

 

sounds like exactly what i have going on. i just bought an IPR re-seal kit for $15 from international. it should be here wednesday, i will post my results. i hear that this problem is the result of bad o-rings in the IPR, and fuel leaks back down when warm.

 

Okay so what is the IPR? I just(1 hour ago) changed my fuel filter, so as soon as I am confident I dont have any fuel leaks I will go out and drive for about 10 mins, then see if I get any of the symptoms I was getting before even though I highly doubt the filter had anything to do with'em. It definatly made a difference in the throttle response and power on demand factor...not much but enough to feel in the "seat of the pants" factor lol.

 

did you start the truck when you noticed the cap leaked??? may be a little air in the line now..if so it will clear up after 50 or so miles..good luck..

 

No.....I had these rough idleing problems before I changed the fuel filter, but noway would I have cranked it with Fuel spewing out like "Old Faithfull". But now atleast I have got the filter changed.

 

is it a hard bucking like the motor is turning off (CPS'ish) but really isn't or is it more of a slight vibration (weak injector)?

 

No its not a hard bucking, but I guess maybe a weak injector type bucking....um IDK really its just seems to stutter very briefly then back to normal during idle, when driveing on the hwy at or between 45-60 mph it is more of a stutter/bucking but just bad enough to feel. When in Nuetral and I rev to and maintain 1300 to 1400 rpms it will stutter but no or very little movement on the rpm gauge but you can definatly hear and feel it stutter.

 

Couple of things to check.

1. overfilled crankcase can cause excess foaming of the oil and strange driveability issues
2. Brass nut on IPR - make sure it is tight (52 in/lbs)
3. ICP sensor - unplug it and rev in neutral at the 1300-1400 and see it it smooths
4. ohm out the valve cover harnesses.

 

Ok...How much above the operating range markings on the oil dipstick is too much oil.....um my oil comes up about 1/4" past the highest marking on the oil dip stick for Hot operating range...could that be too much oil causeing this?

 

Most of the pinpoints start with verifying the engine oil level and draining/adding if overfilled/underfilled. A 1/4" is about 1/2 to 3/4 qt over full, but make sure the truck is level - leaning back will make it read high and leaning forward will make it read low.

 

Ok. well my truck is sitting about as level as possible but the front is possibly leaning down farther then the rear. I also just went out and check the oil level and it was covering the whole dipstick up to about 1/4" and then it trailed up farther on the dipstick but only on the bottom edge....so I am guessing my oil level is high. Can I just siphon it out the dipstick tube?

I also dont have a clue what or where the ICP and IPR sensor's are....do you have any pics you can point me to?

 

Yes, that is the way some people that use extended drain intervals take oil samples.