'99 Navigator issues

[driller]

While I was working out of town last week, apparently the kids borrowed the Navigator and had some problems.

They were on their way back from town when the Navigator "quit running" and the "oil warning lamp" came on. Terrified they had messed up Dad's Navigator, they had AAA tow it back to the house without even trying to restart it.

I checked everything out and found it about 1-1/2 quarts low on oil. It has been burning oil as of late but it hasn't been that long since I last checked it. Anyways, I topped off the oil and it started right up with no difficulty and no unusual noises. The CEL was illuminated. I checked the codes and there were several. The codes returned pointed to lean conditions on both banks, TPS and O2 sensor codes. It also seemed to be idling a little high at around 1000 rpms but otherwise seemed good. I cleared the codes and ran it a bit to see if the CEL would return. It did and again it showed both banks lean.

I ordered a new TPS, and picked up an IAC valve. I plan to clean the MAF, swap the TPS and IACV and check for vacuum leaks. I think the oil light may have just been from the engine quitting unexpectedly?

I'm not sure where else to investigate except possibly throw new O2 sensors at it. It sits much more than being driven and it has been pretty reliable since I've owned it. Any further ideas appreciated.

 

[chris2523]

I think the oil light may have just been from the engine quitting unexpectedly?

probably.
when the engine stalls, there's no more oil pressure.
no pressure, the light comes on.

 

[DLF]

...check for vacuum leaks. I'm not sure where else to investigate except possibly throw new O2 sensors at it.

That would be my suggestion. If you can't find any cause for the lean issue, then try the O2 sensors.

 

[HOTLNC]

Also check your alternator output. When the alternator went out on our old 94 Continental, the oil light came on suddenly. I shut down the motor immediately and checked the oil level. All was good. So I restarted and went down the road. Then other lights started coming on and the speedometer stopped working. The LAST light to go on was the alternator lamp! That is one useless idiot light. My Mark did the same thing. I drove it until the battery could not sustain ignition. That is why I like voltmeters in the dash.

 

[driller]

Wirelessly posted (Mozilla/5.0 (iPad; CPU OS 5_1_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9B206 Safari/7534.48.3)

Also check your alternator output. When the alternator went out on our old 94 Continental, the oil light came on suddenly. I shut down the motor immediately and checked the oil level. All was good. So I restarted and went down the road. Then other lights started coming on and the speedometer stopped working. The LAST light to go on was the alternator lamp! That is one useless idiot light. My Mark did the same thing. I drove it until the battery could not sustain ignition. That is why I like voltmeters in the dash.

That was one of my first thoughts as well. I checked the battery charge and it was healthy. After starting, I checked the charging system and it checked out OK as well.

 

[driller]

Well, I replaced the IACV and the TPS. I had to pull the throttle body to get to the TPS. I cleaned the MAF sensor and put everything back together.

It seemed to run better and certainly idled better at about 800 rpms. I took it for a short drive and the CEL came on again.

Codes:

• P1000
• P0136
• P0156
• P1131
• P1151
• P0171
• P0174

It drove fine, but I don't want to push my luck. It looks like it's time to try O2 sensors?

I checked for obvious vacuum leaks but did not find any though I didn't do a thorough trace of every vacuum route. I am going to pickup a new PCV valve tomorrow on a wild hunch. I cleared the codes and will see what happens tomorrow evening.

 

[chris2523]

P0136 02 Sensor Circuit Malfunction (Bank I Sensor 2)
P0156 02 Sensor Circuit Malfunction (Bank 2 Sensor 2)

so. O2 sensors or wiring i would guess?

 

[driller]

P0136 02 Sensor Circuit Malfunction (Bank I Sensor 2)
P0156 02 Sensor Circuit Malfunction (Bank 2 Sensor 2)

so. O2 sensors or wiring i would guess?

At 177K miles, it would be a good guess. I'm just curious why all the O2 sensors at once.

Bummer, 'cause that means no towing this weekend.

 

[tixer]

Bummer, 'cause that means no towing this weekend.

You've still got a couple days. Get wrenching. Or better yet, blame the kids and make them do it.

 

[driller]

I'm afraid I'm fighting a losing battle.

I replaced the PCV valve (what a PITA). I was going to test fuel pressure but couldn't easily access the schrader valve on the fuel rail. The 5.4L DOHC is a shoehorn fit on the Navi'. It makes working on the Mark VIII 4.6L look like a cake walk.

While replacing the PCV valve, I disconnected the battery to reset the PCM. When I test drove a few miles, I thought I may have had some success but before I got back home, the Check Suspension light came on. The CEL did not come on but I checked for codes when I got back in the driveway.

• P1000
• P0136
• P1131
• P1151

Grrrrrr...

 

[bigrob]

Anxious to see what you figure out, my 97 Mark has exact same symptoms. Looking at around $160 for all 4 O2s plus labor, looking like next attempt. I also have fixed all vac leaks, iacv, pcv, maf, works for around 30 minutes then cel. Lean bank 1 and 2, if O2s are unsuccessful once I get done beating my head into a wall I will test fuel pressure! After that I give up!

 

[opalescent 96]

Maybe check and clean all your computer grounds around the engine compartment.

 

[driller]

To put this to rest, I ended up trading the '99 in, so there was no real resolution.

But the CEL didn't come back and the suspension worked just fine taking it the dealer lot.

In retrospect, it owes me nothing. It has served me well since I've owned it and was relatively problem free (until lately anyways). It has braved the winters here in WV with the Blizzacks like a trooper and has hauled the family and the trailer with my Mark VIII toys far and wide.

I hope it finds a good home.

 

[DLF]

If you can't fix it, get rid of it.

Joe, Are you listening.

 

[Ford nut]

Lol!!!

 

[chestnut101]

If you can't fix it, get rid of it.

Joe, Are you listening.

NOW those are words of widom!

 

[izackary]

If you can't fix it, get rid of it.

Joe, Are you listening.

Bwahahaha... That was the story of my '94 when I traded it in for the '99 Explorer. For the record, that truck took 100k miles over the next four and a half years like a champ. The '94's transmission was starting to go for the 4th time while I had owned it, and at least the 5th time over its short life.