1998 F150 5.4L 4x4

So yesterday i took the plunge and replaced the spark plugs (105000 miles and in TERRIBLE shape) and put in brand new refurbished injectors. The old injectors were making a bad clicking sound during acceleration and i thought they were worn out on the inside. Well today i got in the truck and went for a ride (did the initial drive last night, worked the air bubbles out of the injectors, everything ran like a top after that) and noticed at the drive thru that the injector click was back... disappointed as i am, im also determined to find out why this is happening. Could it be the injector module? Fuel pump? Too much/Not enough fuel pressure? I replaced the fuel filter not that long ago also.

On to my other issue. When the rpm's hit 2300 to whenever it shifts there is a loud whoosh almost like a blow off valve sound behind the dash, almost sounds like its right behind the radio. Nothing is affected by this (i think) i just want to know what it is. I replaced the heater core about a month ago also. Oh and there is no CEL but i have not run a hook up diagnostic yet either. Any info on any of this is greatly appreciated. Thanks in advance!

 

The injectors are solenoid valves and will possibly be heard if the engine is quiet and your hearing is very good.
They must work with precision to open and close like any relay or solenoid.
There is no problem with them just from the clicking noise.
Your other issues, I have no clue.
You have to find them and the cause.
Good luck. .

 

well, these things are exceptionally loud. would low fuel pressure cause them to be loud? i dont understand. it sounds like a diesel..

 

On some years the intake manifold amplifies the sound.
You know they are mounted in O ring seals and the fuel rails are bolted to the upper intake manifold.
The rails may be transmitting the sound you hear.
On my 02 4.6 there is no noise from them that can be heard.
If you feel fuel pressure is a factor measure it to find out.
The pressure should be in the 35 psi range.
Otherwise nothing can be done about it since you already replaced them once with the same result.
Good luck.