Many of us F150 owners are having the ROUGH IDLE problem with our trucks. Someone suggested that i may be bad injectors, one the has a drip or dribble and not a good spray pattern. That the spray pattern may not be as designed. Many of us have had the injectors cleaned, but if its a design problem, or something like that, then the problem wouldn't go away with a cleaning. Has anyone changed injectors on their F150 5.4lt? Did you have to change any other setting on the engine (like the computer) ? How about increasing the size of injectors?? Did you see a noticable increase in engine performance?? How much and what type injectors would we need to try?? Any information would be greatly appreciated. Thanks

 

before you do anything I would check if you are losing pressure.

 

I think the stock injestors are 19lb/hr and can support up to 300hp. I see no need to upgrade unless you are adding some serious HP mods that can use all that extra fuel. When you go swapping injectors is when you have to deal with programming things.

 

KYFORD,
BY SWAPPING INJECTORS YOU MEAN GO TO LARGER ONES?? I WILL NOT BE INCREASING THE SIZE OF MY INJECTORS BUT I WANT TO TRY SOMEOTHER ONES TO SEE IF MAYBE THIS WILL SOLVE THE ROUGH IDLE PROBLEM WITH MY TRUCK. HOW MUCH TROUBLE IS IT TO CHANGE INJECTORS??

 

i changed my injectors on my 4.2 to 25lb and it made a large increase in performance but keep in mind if you change injectors to a larger size you need an ajustable fuel reg to tune them to the proper air/fuel ratio.

 

did anyone get their fuel pressure regulator checked?

 

36racin
Yes I did mean increasing the actual lb/hr size. From what I have read here (Neal and others) have said you really do not nead bigger injectors unless you've got several big HP mods. Maybe you can install a larger injestor as long as the fuel pressure is set right. Wouldthey then just run at less of a duty cycle. Talk more to Neal, Max, Crash, or Skidmark to get exact answers.
I noticed road_rage1 said he changed to 25lb/hr injestors and I assume because of his post he only added an adjustable fuel pressure ratio. Then again he has several HP mods from exhaust to chip and even an ignition system.
Expect to pay at least $65 for each injector and that is an aftermarket OE type injestor.

 

does anyone have any recomendations for size of injectors for an older 5.0? I dont have a mac, so that wouldnt be a problem. I am planning on a NA 5.0, heads, cam, manifold, throttle body, maybe compression ratio. Im just not sure whether or not 30lbs is to high, and if not, what kind of adjusting to i have to do. Keep in mind, all the work will be done in my garage, so i need to know what to do.

 

i forgot to mention that the reasons i changed my injectors to 24lb was that i was getting a lean a/f ratio in bank one and bank 2 so with injectors i also went with a 255lph fuel pump running at 45lbs at full throttel and 35lbs at idle.