So I have a 99 F150 4.6 with 250000 miles. It is idling very rough and if you hold the gas steady say 2000 rpm it gets a little worse. If you pull a vacuum line the idle goes up but smooths out. Also it is running rich. Black soot and I can smell it. Spark plugs and wires are new o2 sensors new egr and the corresponding sensor are new. Throttle position and iac are new. Have replaced numerous rotted vaccum lines. Intake, valve cover, and oil pan gaskets are new. Any ideas would be appreciated.

 

Codes? Might just be burning oil. How long have you had the truck? History.

 

Had the truck three or four months it has ran for maybe one. Had to replace the transmission. Only codes I’m getting now are for the o2’s telling me it’s running rich lol. They are new but I’m guessing covered in soot. It blows so much there is a black spot on the driveway. It could be burning oil but I don’t think any out of the ordinary. I want to replace the o2’s but if that doesn’t clear it up then I ruin another set.

 

Your right on that, running rich can destroy the O2's.

It's better if you post codes (DTC's) for us, - all of them. You haven't owned the truck long; so post all codes you had in the recent past, as well.

Also post warm idle rpms in park. Try to be as accurate as possible.

 

Wild *** guess, since you mentioned rotted hoses - have you checked the fuel pressure regulator? There's a vacuum line to it that lowers pressure based on intake vacuum. Check the vacuum line. And, while you're there see if the vacuum line has raw fuel in it. Not uncommon for the diaphragm to blow and let unmetered fuel through.

Both of those will cause rich running.

Your converters will get destroyed also if you run rich for too long.

 

Lol not worried about the cats they are gone. I have sprayed starting fluid around every line and hose I see and nothing. Replacing the pressure regulator has crossed my mind. The injectors and fuel filter are new. If I had a gauge I would check the pressure. I’ll get the codes ASAP.

 

Yea, - wouldn't use starting fluid, it will most definitely make matters worse with these engines. That stuff will create new leaks quicker than snot and it doesn't work all that well anyway...a gross leaky maybe. Too many adverse effects and problems incorporating that stuff.

Not having any cats will screw up the AF's IF the PCM hasn't been tuned to run cat-less. Your ratios will be off...doesn't help.