Does anyone on this board know anything about the engines of Lincoln Navigators?

My brother's Navi has an idling problem. The engine idles irratically and wants to shut off. However, when the accelerator ir pressed, the engine revs fine all the way to redline. The engine drives perfect under any driving conditions, but whenever you come to a stop or during idle it starts to idle irratically. Sometimes the irratic idle will cause the engine to shut off.


Overall, the Navigator driver perfect. I checked for air leaks and could not find any leaks. I can use someone's help here. Thanks.


1. Check engine light has been on display during this problem.
I reset the computer by disconnecting the neg battery cable,
but after a few hours of driving it comes back.

2. Spark plugs were changed about 1 year ago.

3. Fuel filter was changed about 1 year ago.

4. Navi has new K&N air filter installed.

5. Navi just received a tune up about 1 month ago.

6. No trouble codes were displayed after using the scanner.
Maybe because the computer was reset before the scanner.
At the time the check engine light was not on.


Possible Cause:

1. Navi has 127k miles on motor.
2. O2 sensors have never been changed. Could be faulty.
3. Navi is using lots of gas and you can smell it during driving.
Navi is running really rich.

 

I am having similar problems with mine, does not sound as bad as his though. Mine threw a misfire code. Maybe check the coilpacs.
If the code comes back go to autozone and get the code read, that will point you in the right direction.

 

IAC valve maybe

 

1. wrong forum.

2. disconnecting the battery and turning the light of doesn't help anything. you need to get it scanned for codes, the light is on to let you know that the pcm has stored some info that should help figure out the problem.

3. it could be any number of things, but a code would at least get you pointed in the right direction.

4. Navigators and Expeditions are famous for having the PCV hose rot/deteriorate and create a vacuum leak which could cause your running rough/ cutting off at idle. the pcm would show lean codes.

5. Navigators are famous for having sticking valves, you could have an intake or exhaust valve hanging open. the pcm may or may not store missfire codes.

6. could be a bad IAC

good luck.

later,
chris

 

My vote goes to either:

a) Bad IAC

or

b) Over-Oiled K&N Covered the MAF sensor wires with oil and MAF needs to be cleaned

-Dale

 

Superfords, good point you pointed out. I'm not the expert that's why I'm on this forum. I checked the PCV valve and found no leaks. I will return to Autozone to get a code check to point me in the right direction. If you have anymore ideas, please let me know soon. Thanks again.

 

No matter what the cause of the idling problem, replacing the O-2 sensors will pay for itself in fuel savings and improvements in drivability. Once you get to 100k, they are pretty well dead and very slow to respond. As a rule, I change 'em at 60k.

 

I too think the o2 would be worth looking in to.

 

You said you checked the PCV valve, but did you trace the tube all the way back to where it connects to the back of the throttle body , up close to the firewall... There is a rubber elbow back there that rots out and causes a huge vacuum leak. Reach back there with the engine running and feel for a leak.
My Expedition and a friends Navi both had this problem at about 120k miles.
This will cause lean bank codes and mass air codes, because of the unmetered air getting into the system.

 

about O2 sensors would it matter if I bought the stock ones or an aftermarket one?