Hello all,

First of all, my truck is a 1997 4wd with the 5.4

I have an issue with the throttle that is dragging me in circles. First, the gas pedal will get stuck and be near impossible to move, then it will finally break free, and the engine redlines, while the gas pedal becomes limp and has no resistance and does not spring back up, but rather just flops around. So after turning the vehicle off, i check the engine, and the butterfly valve on the throttle body is perfectly functional.
So, the next step was to take off the plastic duct that connects the air filter and the throttle body. This allowed me to view the butterfly valve. Upon starting, the engine once again redlined on its own, although the butterfly valve has not opened more than if it were simply at an idle. So i figured this to mean that the engine is running extremely rich when this occurs, since the throttle is barely opened, yet it is still redlining on its own. So i took off the throttle position sensor and replaced it, since thats what i figured it was. After changing the TPS, the engine still goes straight to redline once it is started though.
Am I missing something simple, or is there a bigger issue here? I just can't figure it out.

So basically:
-start engine
-revs up to redline
-butterfly valve on throttle body open only to "idling" position
-engine is running almost entirely on just gas

Also, it should be noted that earlier, I had discovered that my throttle cable was too long, and that at the throttle body, there was a little bit of slack, and that slack has now moved to the gas pedal end of the cable, which explains why the gas pedal is free to move (excess cable is in the cab at the pedal). But the cable at the throttle body still isn't making the butterfly valve move, its just in its normal position. So I know the cable needs to be replaced, but it isn't affecting the throttle at the moment.

Anyone able to offer any ideas as to what is wrong? I am at a complete loss as to what I should do next.
Thanks in advance

 

Just for giggles...shoot some carb spray or tb spray on the spring on the side of the tb....where the cable hooks. I've had those get crud in then, and make it so i'd have to "pop" the pedal. But....sounds like your prob may be a little more....still a good place to start.

 

Sounds like your IAC is sticking wide open.

 

Thanks for the replies so far. I did a little research into the IAC, and that could be the problem. But my question is would that be the cause of this? Correct me if I'm wrong, but wouldn't the IAC just let more air in, not gas?

I ask because when I start the truck, gas fumes are everywhere, and the entire cab stinks of gas.

Also, would the IAC wide open be able to supply the engine with enough air for it to get to the redline?

 

Check your oil level...is it gaining? if so, then you prolly got injectors that are sticking wide open or fuel regulator that is shot. Might be wise to check the fuel pressure.

It also couldn't hurt to remove the whole Throttle Body Housing (TBH)...give it a thorough cleaning...2 interior EGR ports tend to get clogged with carbon deposits....plus, with it removed, it is a whole lot easier to remove the IAC weather you clean it ot replace it and check the PCV elbow that attaches to the TBH.