Hi there im new here and new to Super Dutys but i love them! Altho mine is not being so nice. It has the 5.4 in it. When its idling it has a stumble to its idle with a pop every now and then out the exhaust. It revs fine when its first started. If i pull out on to the road and start away easy its ok a slight miss but if i put the throtle down its just falls on its face. But if i get it up to crusing speed its ok as well. But even at crusing speed more then 1/8 throtle and it starts missing and falling on its face. Any ideas what it could be? It smells like its running lean as well.

 

Welcome to the site!

What year truck?
Fuel pressure test will tell you if the pump or filter need replacing..
Clogged exhaust? Have a experienced mech look at it. Don't guess..

Dick

 

check engine light? ...maybe mass airflow sensor, vacuum leak, or low fuel pressure

 

First thought I had was exhaust.. but I'm not an expert at all. Any codes or CEL on?

 

ok how old is it(what year) has it ever been to get new spark plugs???fuel filter or air filter find a mech. or a tech to help

 

I am an experienced mech/ tec just not with these trucks. I figured id hope on here and see if any of you had experienced the same or similar issue and had a fix for it. I changed the fuel filter and the exhaust is cat-less with a glasspack so its open. the front 4 coils are yellow (unknow brand) and the back 4 motorcraft. Not sure when the last time the plugs were changed, but again I fell its starving for fuel. It feels like all the cylinders not jsut an isolated issue. Maybe the Fuel control module? Dose it even have one? Thanks again for all the help!

Harry

 

Truck is a 2000

 

Check engine light was on so I cleared the codes hopping what was wrong would bring the light back on, but it didn't. Not as of yet anyway. I was thinking mass air as well but them seem to run okay and not really fall and die at throttle with it un-pluged so I didn't think it would cause it.Am I wrong? Cause that would be such and easy fix!

Thanks for all your advice and help!

Harry

 

fuel filter is what it sounds like to me.. drivers side fuel rail just below the door jam front side.. start there. if that dont work.. hit the plugs up.. if thats not it start swapping COP's

 

Fuel pressure has to be 35 psi or so all the time...

 

Thanks man! That's a tool I don't have never really needed one lol ill borrow one tho and test it next before I do anything else.

 

auto zone rent them for $150 and you get a full refund on return

 

The fuel filter has been changed, it helped a tad but not enough. I changed the air filter but haven't cleaned the mass air yet. It doesn't act like a fire issue but I will change the plugs anyway. Like i said it doesn't act like it's linked to one cylinder. Is there a method to changing the plugs with out causing damage? any hints or tips? Whats the torque on the plugs?

Thanks for all your help!

Harry

 

No auto zone north the boarder lol. I got a buddy who's owns a shop ill borrow his snap on one.

 

What were the codes before you erased them?