2001 5.4 250 SD Rough Idle
 

While idling and driving, the idle is rough. Just started today. response from accelerator varies. Vibration when I push the pedal. Have no idea what this may be, but I don't like it. Any opinions/similar experiences?

215,000 miles
2001 SD model
5.4 V8 GAS

Any help will be appreciated!

In addition, I have noticed a distinct smell of fireworks (sulfur??) when I turn the truck off and get out. I have thought it may be the fuel filter, fuel pump, or something within the oil distribution through the motor. I would like to narrow it down before I start trying to fix it if at all possible...

I would start by checking your IAC valve. (Idle Air Control). Also examine all your vacuum lines closely for tears, rot or cracking.

Clean throttle body and IAC but the sulfur smell could be a plugged Cat. It the truck stubbling under load? That could be a coil pack. Also in use used and oiled air filter could be a MAF issue.
Good luck.

Judging by the sulfer smell, I would bet on a plugged cat, like Eric said.
Easy way to check for that is remove the 02 sensors and see if you get alot of exhaust from them or take it for a short drive to see if you get power back and clears up the idle.

I wouldn't worry about the sulfur smell until you get the idle fixed. The sulfur smell may be caused by the truck swinging from lean to rich to lean as the FI system tries to compensate for improper IAC operation, or may be caused by a misfire and raw fuel/air getting to the catalytic converter.

A plugged catalytic converter will usually show itself by a lack of high end power or acceleration, but idle and low RPM operation will be OK.

Your correct REDFORD it shouldn't affect the idle, A bad MAF sensor could be the culpret too. ????

Good point Rick. A bad MAF sensor will USUALLY affect the idle, but not always, so it should be checked and/or cleaned also.

i have the same problem, the engine seems to buck on an irregular pattern during idle and it has the same vibration at about 40 and you try to get on the throttle, it also seems to hesitate. the exhaust is pretty short, it kackles if you rev it high and back off quick. could this be from lack of back pressure? not the kackle but the hesitation and jumping.

my uncle is coming by today with his computer for cars, not just the code reader but the nice one with the graphs and stuff to see about the misfire possiblity. ill post later tonight of the out come.

DAAN-O :

That is exactly what is happening. Anything you find out will be extremely helpful. Please let me know as soon as you can! This is scaring me - I have no other vehicle!!!!

As to all other replies:

I am looking into ALL possibilities, as the truck does have 215,000 miles.... Thank you all for your help and input!!!!

i recommend checking and cleaning MAF, IAC, and checking all spark plugs and connector's
Unplug battery and then let it idle and drive around see if that helps.
Also when has the fuel filter been changed if it hasn't for a while could be getting low fuel pressure at idle.

Ethanol could also be the problem. If it has been sitting a while it could have seperated and shot it full of straight alcohol. My 5.4 had a problem with it one time and it wiil also smell like rotten eggs. I am lucky to be able to buy ethanol free gas where I live at all times but when I travel it can be hard to come by. Just my 2cents. Steve

It hasn't been sitting. I drive daily. I am leaning towards the MAF, IAC, Fuel Filter, and a full tune up - including plugs and wires. After that, I have no idea what would make it run the way it is running right now. Again, I thank everyone for their input, and I will try it all out before I go completely nuts!

Will post an update when I find out what the problem is. I know Daan-o had the same problem....

After you give a good tune up you'll see a difference. Besides needing the tune could be a bad COP. Start with the easy things and workup eliminating the simple fixes.