My truck.
2005 F250 CC 4x4 SB V10 4.10gears 101,000 miles.

Love the truck, not the mileage, but Love it.

BIG improvement over my 99F150 4.6L 4X4 SC when I'm pulling the trailer, (3000lbs loaded). And better mileage when pulling!

Just recently surpassed the 100,000 mile mark and did the oil and air filter change and switched over to Mobil 1 5-20.

Have noticed ever since idle speed is wandering, 800-1000-1200, up and down and back and forth.

Any suggestions?

Don't know if I'm still running original plugs, know that they are due @ 100k. Read all the horror stories about them breaking and coming out in 3 pieces.

No CEL, mileage is still the same 10.5-12.

Should I take her in and have the plugs changed out and COP's checked?

Would the switch to Synthetic cause the problem with idle speed?

Would like to hear your thoughts and suggestions.

Dan B.
Central Ks.

 

First:
If you have not changed the plugs that is definately needed. Expect a couple to break since you have waited. If you are going to do them yourself, replace the plugs, boots and springs for the COP's. No need to replace all 10 C.O.P.'s on these. Just replace them as they fail or throw misfire codes. I would also replace the PCV valve and the Fuel Filter.

As far as the idle I am not sure if the have an Idle Air control valve but that may be a place to start. As I mentioned though PCV valves and Fuel Filters can help tremendously. You may want to check for vacuum leaks as well. This can cause surging idle.

 

The 2005+ is a fly-by-wire throttle system. The idle is controlled by the computer by directly controlling the throttle plates. For it to wander, there is either a vacuum leak, or the MAF is dirty. (or some other stuff, but the first thing is to check the MAF).

 

Thanks to all,

Idle has settled down since oil change last week.

Still not sure what caused it as I was near nothing on the top side except for filler neck and dipstick, but did change out air filter.

Will pick up PCV and fuel filter and make an appointment to have plugs, boots and springs replaced ASAP.

I always thought that the F150 was the best thing on the road. Super Duty puts them to shame.

Love my truck!



Dan B.
Central Ks.

 

Thanks to all,

Idle has settled down since oil change last week.

Still not sure what caused it as I was near nothing on the top side except for filler neck and dipstick, but did change out air filter.

Will pick up PCV and fuel filter and make an appointment to have plugs, boots and springs replaced ASAP.

I always thought that the F150 was the best thing on the road. Super Duty puts them to shame.

Love my truck!



Dan B.
Central Ks.