Birdman1974

Good morning my name is Chris and I am new here. Thank you for having me on the site.
I have a question about a 2008 F250 XL with a 5.4 motor. The truck seems to surge very little, but you can feel it when holding onto the steering wheel. When it does surge the RPM Needle does not move. I tried cleaning the throttle plate. I looked for leaks on the hoses, but nothing. Not sure what has been done with the truck. My son bought it. I’m wondering if I should change out the spark plugs? Is there anything else that would cause that surge to do that? Thank you very much.

laterongc

you haven’t provided much to go on. I don’t know what a surge is (means) without rpm change.

assuming this is relative new to you and without service history, I would:
- scan for codes; write them down, then clean them
- run an engine oil flush, carefully inspect drain oil and cut open filter and inspect.
- use 5w30 and good filter after fluah
- inspect air filter, should be clean and make sure it has a tight seal around edges of box
- drive it a lot, get up to temp, put it through its paces, see if symptoms have changed
- rescan for codes

post back with what you learn, try to be specific.

Jimboy

Vacuum leaks are my first thought. Do you hear anything that sounds like hissing associated with a vacuum leak?
Just a thought - this is a longshot
Application of the brakes could cause a surge without a noticable rpm change. These trucks use brake shoes for the parking brake and there have been cases where the friction material falls off of the shoe and causes what I would call a surge. After driving for a while and noticing the surge check a see if the rear brakes seem excessively hot/smelly/smoking.

Birdman1974

Okay so I scanned for codes and it came up with O2 Sensor Bank 2 Sensor 2. Air filter is new and box is sealed tight. I checked hoses for an EVAP leak. Didn't see or hear anything.
I start the truck at first and runs good.
Once it's up to Temp that's when I notice it.
It seems like the RPM goes up a little and back down. But when it happens the RPM needle never moves. Then it runs fine for a minute or two then does it again. This is just at idle.
It's more noticeable when driving. Oil is a little dirty so I'm going to do an oil change and flush it tomorrow. I did replace that O2 sensor. The tip of the O2 was a grayish color. I believe that means it's running lean? Is that Right?
Unfortunately there is No service history on this Truck. My Son bought this truck this pass Fall. It has 85,000 miles on it. I was thinking probably replace the Spark plugs and fuel filter to Start with at least this. But just don't want to throw parts at it and hopefully that will fix it.

laterongc

are coil boots brown or black?

manicmechanic007

Surge?
Don't usually get that complaint on the newer ones
The processors respond quicker on the newer ones
Slight part throttle surge on a 1994 Ford is about normal
A 2008 not so much
Check the codes, clean the throttle plate and clean the fuel injectors (professionally) (through the rail).
The HEGO sensor should have a brown or gray color.
Absolutely do replace the spark plugs and the coil boots for maintenance. Use Motorcraft spark plugs and anybody's boots