Did you replace the plugs,wires? a bad plug o wire can cause a bad idle. Vacum leak could do it too.
Testimonial: "Yes, plugs and wires replaced. Will go back again and have him check plugs and wires to see if bad - at least I have a little knowledge now, thanks to you. "
If the rough idle comes and goes (intermittent), it could be the EGR. I just replaced the EGR on my 2001 F150 5.4L. When it got below freezing, the truck would stall as well.
"Owners of some 1997-2005 Ford Trucks with the 5.4L two-valve engine may complain of an intermittent rough idle. One likely cause, says Ford, is noncommanded EGR flow. A stuck open EGR vlave is ultimately the culprit.
To make a definitive diagnosis, connect your scan tool, start the engine and allow it to reach normal operating temperature. Next, allow the idle to stabilize, scroll down to the DPFEGR PID on the scanner's display and write down the voltage. Now disconnect the vaccuum hose to the EGR valve and connect a vaccuum pump to its port. Pump the vacuum up until the EGR valve is wide open, then bleed off the vaccuum. Record the DPFEGR voltage again. Repeat this procedure several (about 8) more times.
If the DPFEGR voltage increases by .03 volt or more from the initial reading and the idle gets rough, the EGR valve is probably stuck open. Try tapping the casting with a wrench. If the voltage decreases and the idle now gets smooth, the valve is definitely sticking. Replace it with a revised design, Part No. XL3Z-9D475-CA.
Trucks that can benefit from the upgraded EGR vlave are 1997-99 F-250 light duty pickups, 1997-2004 f-150s, 1998-99 Lincoln Navigators, 1997-2005 E-series vans, 1998-2004 F-super duty pickups and 2000-05 Excursions."
Anyone with an intermittent rough idle please read...
Anyone with an intermittent rough...
SOURCE: 1994 ford escort vibrates horribly in idle.
Your Idle air control valve is probably going bad. It is located on the throttle body and is a relatively easy fix as it is only held in with 2 screws. Good luck and thanks for using FixYa!
SOURCE: 1996 FORD CONTOUR 4CYL ROUGH IDLE ROUGH ACCELERATION
no problem. If you are getting that low of voltage on a load then you might want to test the alternator as well to make sure it is running at capacity.
SOURCE: 2005 ford explorer 4.0 sohc
Try replacing your fuel filter. If it is dirty then sometimes it causes issues like this.
SOURCE: 1997 ford escort idles rough when hot
1997 escort idles rough, the first thing is to make sure the throtlebody plate is clean. This sounds like the idle may be staying to low at times if it smooths out with ac on, when the ac is turnned on the computer raises the idle a touch to make up for the strain on the engine from the ac compressor, clean throtlebody and look at and clean idle air control valve, if this valve is not controlling the idle when needed the engine will idle lower than normal and cause a rough idle.
Another thing is the sparkplug wires, take a look at those, if at night or with a good eye use a spray bottle and spray a mist over the wires and watch for any sparking, this spark may be very small so look at each wire closely or may be big enough to see and hear. this is where i would start. good day.
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