03 navigator rough idle at stops - Ford Forums

jagb2507 · 10-09-2009, 20:18

2003 navigator w/ 60k on it, lately when i get to a red light i feel a vibration in the vehicle, more so on cold days, but never during acceleration or any other time, just when in gear and stop... any ideas where to start??

**rtg143** · 10-09-2009, 21:22

There's an extra load at idle and in gear so an engine miss will be felt easier. If you haven't replaced the spark plugs, this would be a good time to do it. There's a possibility that one of the coil packs is bad. It will eventually cause a check engine light and code.

jagb2507 · 10-09-2009, 23:54

thank you for the reply, I will look into changing the plugs but how would a bad coil pack be detected? my friend suggested a vacuum leak? is that also a possibility? if so, how would one diagnose?

**rtg143** · 10-10-2009, 08:55

A vacuum leak is rare on them. To check a coil pack, you can umplug one injector at a time and see which on doesn't make a change, then switch it with another one and se if it move to the new location. If it's in a hard to get to location, move it to an easier place. See if the miss moves with it. You can usually feel a miss just setting there and not in gear. Also look at the rubber boots to make sure they aren't cracked causing a spark jump. When you change the plugs, make sure you use anti-sieze and a torque wrench. too tight and the cyl. head exands and pulls them out. If you have 5.4, be very careful, the plugs sometimes brek and special tools are needed.