Its an 01 f150 5.4 and it idles just fine but the other day, i slammed the gas and did a circle burnout in the dirt and after i let off, the rmps dropped way down and it sounded like it was going to die, it didnt die but almost. This also happens if i hit the gas real hard and come to a fast stop on the street also. Anyone have any idea what could be wrong? Thanks.

 

Fuel Filter

 

Thanks, but i changed it.

 

Well , list everything you've done to solve the issue

 

Well i really dont know whats wrong or what to do but ive changed fuel filter and plugs so far.....

 

What plugs did you use?

 

Motorcraft plat.

 

What you discribe seems to be a faulty 'dashpot routine' operation.
Most here never heard of this but it is a control routine the PCM uses to keep control of the motor if the throttle is suddenly opened and closed without the drive line attaining the matching speed and providing input.
What this does when the throttle is jazzed like that, is the PCM looks at the 'rate' of TPS movement and adds more fuel than it normally would in antisipation of accelleration that never happens. The tranmission also has to supply a signal telling the PCM what is happening; it never does in this situation. So the motor ends up in a bit of control confusion until recovery takes place by other means if the dashpot control feature is faulty.
The old carbed cars with auto trans had the feature to prevent the motor from dieing and is carried over to modern vehichles that have the equivelent feature in software and hardware action.
The fault may be a problem with the OSS signal to the PCM because the PCM has to recover the idle by opening the IAC in reference to what signal it gets from the transmission.
It is in part, the same action that occurrs when the truck is coasting to a stop.
The thottle is closed, the IAC closes down almost all the way, the fuel is shut nearly off, the OSS or trans speed sensor tells the PCM the truck is slowing so the PCM can keep the IAC modulated and bring fuel back, to prevent motor stall as the speed drops to idle.
Normally all this is transparent to the driver until a fault developes and stalling , idle drop and recover takes place to indicate a failure.
May be tough to run down if there is no code set but that's what it sounds like.
Be sure the IAC has no operating problems and go from there checking the other actions for a fault.
A dealer check with there test equipment for the correct reactions to a throttle jab should uncover the fault if they can understand what it is they are looking for.
At least you have some idea now of what could be happening.
Good luck..hope you get lucky and it's a simple problem to find..

 

What is IAC abbreviated?

 

Idle Air Control

 

Thanks, and where is it located?

 

I had the same problem on a honda with a manual trans. It got to the point where it would die if i didnt give it gas at idle. Turned out to be the o2 sensors gone bad.

 

Thanks for the help.

 

I'm about to change the plugs in my 97 5.4L but I got the autolite platinum plugs instead of the motorcraft...think this will be ok?

 

Probably, all ive ever used is motorcraft.....My opinion with parts and fluids is, as long as you change them regularly at the appropriate mileage, its better than not changing them at all and you should be ok......