Got a 1999 navigator w/ 80K miles on it. Just today, it's stalled out 3 times while at stop signs/stoplights. The service engine soon light came on and there's a whining coming from the engine. All fluids are fine. Any ideas?

 

Inspect the PCV hoses closely. The whining you're hearing is probably whistling from a vacuum leak. With the 4V engine, inspect the vacuum elbow on top of the intake manifold under the shroud that covers the throttle linkage/cables (it's held on by 3 - 10mm bolts). The elbow most commonly deteriorates and starts leaking right at the 90 degree bend. Your check engine light is most likely because of lean codes, P0171 and/or 0174.

Here's the bad part though - that elbow, from Ford is only serviced with the complete PCV tube assembly. Which, depending on which one your Navigator has, can be anywhere from about $30 to $75ish.

 

Great, thanks for the tip, I'll check it out this a.m.

 

Just checked it out. Dang, was hoping that was it. The hoses and elbows all look to be in about 100% condition.

Wondering if it's bad gas now. Filled up the night before last and it ran OK for about 40 miles but I didn't hit many stops. At stops, the nav idles really rough and has stalled out 4 times now. Am going to try dri gas and if that doesn't work, take it to the dealership. I've gone through 3/4 of a tank, if I add dri gas, then fill up will this fix it if the prob. was bad gas? Thanks again!

 

Look at all the PCV hoses very closely. I've just seen way too many in my personal experience leak. I don't remember whether a '99 has a heated PCV valve or not, but in any case, trace every hose in the PCV system and eyeball 'em very hard. Failing that, limp it down to Autozone and get the codes scanned for free. Then we can go from there.

 

OK, I'll take a closer look tomorrow a.m. when I get a chance. It's not stalling now, but the idle is pretty rough at best. I tried dri gas in case it was bad gas/water but the idle's still very sketchy.

I'll let you know what I find out tomorrow am. Appreciate the help!

 

Quintin, you don't htink that could be the old IAC valve issue?

 

What's that, you're scaring me

 

It's possible, but I've seen more leaky PCV tube connections on the 4V engines than stuck IACs.

 

Its nothing really, the IAC (idle air control) valve just gets bunged up with carbon and other misc crap and doesn't function worth a chit. Then, the amount of air at idle isn't right and it stalls, runs poorly, whatever.

Its not that bad either, bout $100-$150 for the part and only two screws hold it on.

But, quintin is the man with these things so he knows.

By the way quintin, they can't fix the aviator. They have a data recorder in the thing now for me to push the button and record the problems. I called lincoln and told them to fix it, replace it, or take it back.

 

Quintin - you were right about a couple codes. I rechecked the hoses and they look good. I went to AutoZone and pulled 6 codes: P0171, P0174, P0136, P0156, P1131, & P1151. My guess is an O2 sensor, but I'm no expert. I also researched and saw that it could be a bad MAS, vacuum leak (PCV), or dirty fuel filter. Thanks again!

 

With that package of codes, I'd still lean towards a vaccum leak problem.

With a vacuum leak, you can get extraneous O2 codes..

Did you REALLY check that PCV hose elbow back there behind the throttle body next to the firewall? It's really hard to get to...

Steve

 

Exactly where is this? I took off the plastic cover and followed those hoses. They are in about 100% condition and all seem to be hooked up. Guess I'll be triple checking...

 

0171 and 0174 are banks 1 and 2 lean, 0136 and 0156 downstream HEGO heater sensor codes, 1131 and 1151 are upstream HEGOs stuck lean. My gut is still saying vacuum leak.

 

You were right. It was on the PCV hose right under the throttle body cover (top back). The elbow had a small hole in it right at the bend. I ordered another complete setup for $50. It should be for an unheated PCV right? Thanks again, hope this fixes it. They'll have it tom. a.m. and I'll post back and let you know.