One more problem... Vacuum leak Maybe?

[imjustagirl]

I have an 05 f-150 v8 4.6 L. I have a rough idle! I replaced the egr valve, also spark plugs, air filter, fuel filter recently, but nothings helped. What do you think the cause is? And if it is a vacuum leak, how can I check?? Thanks

[Minnesota Sun Bird]

I have been told one can go over hoses carefullly while idling the engine in a well ventilated area with a unlit handheld gas torch with the gas coming out and when your near or on the leaking hose, the engine will increase speed noticeably.

[imjustagirl]

Also - now with the rough idle comes flickering internal lights!! it seems 'in tune' with the rough idle problem. I have replaced everything - I guess checking for a vacuum leak is the next step

[Twinsdad98]

Flickering of lights? Probably just the change in idle speed and charging of the battery. You might have a bad coil, when you replaced the plugs, did they all show the same wear? One cylinder look different?

[imjustagirl]

All of the coils look the same. Maybe youre right about the changing of the speed/battery. thanks

[VFR_Man]

As many reports as we have seen of sticky injectors, it wouldn't surprise me if it could be that causing a rough idle too. A cylinder w/ a sticky injector probably would have had an especially carbon fouled spark plug.