Hey guys I need some ideas I have a 99 f250 Super Duty with the V10 and a couple days ago I hoped in it and drove it a couple miles then switched it off. A few minutes later when I fired it back up I pulled out of the parking lot and found I had a steady miss/stumble when accelarating or cruising under minimal load. A mile or so later I pulled over and let it idle for a few minutes to find it eventually had a rough idle. Now it seems when I first fire it up it runs fine but by the time I get to the main road (about a mile) it stumbles when I apply the gas. I tried reading the codes but it says there is none..

Whats you .02?

 

You should be seeing a code sooner or later; I wouldn't be surprised if a COP went out. That's what mine did after changing the plugs - some of the COPs were old and corroded that they didn't make enough contact anymore with the spring that hooks up to the plug itself... I have one yellow COP now, and 9 black ones 8)

 

I just ordered 10 new DG508's(COP's)...

from here..

http://www.dieselfiltersonline.com/D...08-Dg-508.aspx

 

COP most likely. When my 99' started doing the same thing I replaced all 10 for under $100 with ebay COPs.

 

since your commiting to new COP's you might aswell throw new motorcraft plugs in there at the same time..

no point having to go back in later if the COPs dont fix the issue.

 

I plan on it my friend! These plugs only have about 10,000 miles on them but I plan to put new ones in anyway, just in case...

 

Knowing my cop's would not be here before Tuesday I got a single cop from the local auto parts store and decided tonight to try and find the corporate (because I can't strand my truck being down that long). After swapping several coils with no luck I finally hit the jack pot on the second cylinder back on the driver side, now she purrs like a kitten, for now anyway...

 

I had the same problem code p0302 cylinder 2 misfire.. Put a new COP on and running like a champ!

 

When I first purchased this truck I installed new plugs, changed all fluids, belts, brakes, and added the five star 87 performance custom tune and seen 15-16 highway mpg. Over the last 5-6 months I seen my mileage was dropping with no big misses or anything and had no idea why (over the last few months I was averaging about 12).. By changing the one coil that went completely bad my mileage immediately jumped to 13.6 on the next tank.. I got out yesterday and installed the 10 new motorcraft cop's and my truck now runs so smooth if you looked under the hood you wouldn't even know it was running if it were not for the fan spinning.. I have high hopes for the mpg on the next fill up, if it jumps back to 15-16 I am sure these cops will pay for them selves over time...

 

My V10 seems to be sputtering when I press slightly on the gas, but when I press harder, like over half throttle, it perks right up. Does this sound like the COP's, or is another issue more likely?

 

It could be but does it down shift before it smooths out? How is it at idle? Does it have a slight miss at idle?

With a cop bad mine would miss until it down shifted then it would seem to run smooth...

You might want to check the vacuum hose below the throttle body before buying a cop.. These hoses are bad for getting weak causeing issues.. I replaced mine with a hard plastic elbow with hose on both sides which removed the soft bend in the hose it self. If yours does not down shift before smoothing out it sounds like it could just be a vacuum leak..

 

It runs smooth at idle, and it also doesn't need to downshift before smoothing out. I looked at the vaccum hose, it doesn't seem to be cracked, but I think I'll replace it first, and see if that does the trick. Thanks for the tip.

 

A lot of times the vacuum hose will get soft and when you press the pedal and vacuum climbs it will suck the hose together and over time will cause it to crack and leak so I always replace the elbow with a hard plastic elbow fitting from the local auto-parts then use hose to attach both ends so you know it will not pull closed..

Any time bro, glad I could help!

 

Well, I replaced the vacuum hose you recommended, cleaned the MAF and the throttle body, and replaced the air cleaner. I guess my next step is to replace the fuel filter. After that, maybe the COP's????

Any other suggestions? Not sure I am comfortable replacing the COP's myself, this motor is in a van, and the ones in the middle look like a bitch to get out.

Also, let me be more specific about my problem. The van runs smooth at idle, and performs well under most circumstances. When I get hesitation, is under light throttle. It is most easily duplicated when traveling about 50mph, then lifting the throttle, and then dipping into the throttle again very lightly. It hesitates and bucks, until I dip into the throttle more heavily, typically downshifting.

 

Possibly a faulty throttle position sensor?