Wednesday 26 October 2011

My 2004 F150 4.6L V8 has a low idle and idle will surge, and it will also stall out when stopped?

I cleaned the k%26amp;n air filter, changed the oil, added fuel injector cleaner to the gas, but my truck is still stalling out when I am stopped. It seems the idle is way to low, like hovering around 200 rpms. What could be effecting it?My 2004 F150 4.6L V8 has a low idle and idle will surge, and it will also stall out when stopped?I worked in Ford Engineering designing Mass Air Flow (maf) Meters.



All the time we would get MAF back from k%26amp;n cars. When you oil those filters up oil gets suck in to the clean air. This oil gets on the MAF hot wires and causes a rich/lean condition.



Spray off your MAF hot wires with brake cleaner. Start with that. DO NOT try to scrub the wires with any brushes or things A good spray with BRAKE CLEANER only. MAF cleaner is the same stuff, but a smaller can and more expensive.



Brake and MAF cleaner is laquer thinner in a can.



Try this you have nothing to loose.



Oh yeah - The maf is the electronic module right after the air cleaner before the throttle body. You will see some wires connected to your clean air tube thats the MAF. If you remove the MAF from the clean air tube and look at the part that hangs down into the tube, you will see some small silver wires with a glass bead in the middle. These wires are small and fragile. There should be no oil., grease, spiders, bees wings, or paper on them.





If that doens't work there is an Idle Air Control (IAC) that lets air past the throttle plate. That might be messing up or be blocked.
My 2004 F150 4.6L V8 has a low idle and idle will surge, and it will also stall out when stopped?
Sounds like a problem with fuel or air supply. Might want to check your air filter install, make sure you didn't change anything or block anything. Not saying you would have, but best to start where you've been messing with first.

If that checks out, have you changed your fuel filter? Sometimes a clogged filter can cause fuel supply to be cut off. If changing that out has no effect then the fun really begins. You may have to bring it to a shop to get it diagnosed, but it could be anything from a shot sensor to a dying fuel pump.

TPS, IAC, MAF, and MAP are all related sensors, and there may be some others I don't know about. If you can, remove the IAC and TPS and clean them and the passages up a bit with carb cleaner if they're dirty. It could also be that the o-ring seals on your injectors are toast, repalce them if you can. Might also want to check the condition of your spark plugs and wires.

That's all the cheaper fixes I can think of, because after that you get into replacing sensors or the fuel pump.

Or maybe it's something else entirely, I'm not too experienced with trucks.
My 2004 F150 4.6L V8 has a low idle and idle will surge, and it will also stall out when stopped?
do u have a engine light on?