P0171 Not the PVC elbow. Cleaned MAF.

[jbanks]

Hi all,

When I got this Navigator it had TERRIBLE IDLE and the CEL was on. The rear suspension was also down. I have done the Monroe conversion and some other suspension work.

Since the IDLE was so bad I checked the elbow on the back of the Manifold and it fell apart in my hand. So, I ordered the hose with PCV from Ford and replaced it. Never read the original codes though. I had disconnected toe battery to disconnect the Air suspension light so the codes were reset and I never saw what it was there.

With the new hose it ran TERRIFIC. Absolutely no idle problems or other drive-ability problems. Got my state inspection done and drove it about 500 miles. Then...wouldn't you know....I was leaving on a trip and the CEL came on, basically on the way out of the driveway. So...I went to Oreilly's and had them read the code. P0171. I thought no problem and went on my trip anyway. On the trip I used MAF cleaner to clean the MAF and some throttle body cleaner to clean up the throttle body.

The light has been on about 600 miles now. I went back to Oreilly's to see if there were any NEW codes but there are not. Still only P0171. I wanted Oreilly's to view the live data to check the fuel trims and I wanted to spray some carb cleaner into a vacuum line to check the O2 sensors but their scan tool Innova 3120 will not do live data

There is black smoke at the exhaust like it is running rich.

I have looked at most/all of the vacuum lines and don't see anything wrong.

I know someone with a better scan tool so I will try to go check that out

If I check the fuel trims and the O2 and come up with nothing...I think I am going to try to get the intake smoke tested.

I had also read it could be an exhaust leak near the first O2 sensor on bank one.

Anybody have any suggestions?

 

[toms89]

Hi all,

When I got this Navigator it had TERRIBLE IDLE and the CEL was on. The rear suspension was also down. I have done the Monroe conversion and some other suspension work.

Since the IDLE was so bad I checked the elbow on the back of the Manifold and it fell apart in my hand. So, I ordered the hose with PCV from Ford and replaced it. Never read the original codes though. I had disconnected toe battery to disconnect the Air suspension light so the codes were reset and I never saw what it was there.

With the new hose it ran TERRIFIC. Absolutely no idle problems or other drive-ability problems. Got my state inspection done and drove it about 500 miles. Then...wouldn't you know....I was leaving on a trip and the CEL came on, basically on the way out of the driveway. So...I went to Oreilly's and had them read the code. P0171. I thought no problem and went on my trip anyway. On the trip I used MAF cleaner to clean the MAF and some throttle body cleaner to clean up the throttle body.

The light has been on about 600 miles now. I went back to Oreilly's to see if there were any NEW codes but there are not. Still only P0171. I wanted Oreilly's to view the live data to check the fuel trims and I wanted to spray some carb cleaner into a vacuum line to check the O2 sensors but their scan tool Innova 3120 will not do live data

There is black smoke at the exhaust like it is running rich.

I have looked at most/all of the vacuum lines and don't see anything wrong.

I know someone with a better scan tool so I will try to go check that out

If I check the fuel trims and the O2 and come up with nothing...I think I am going to try to get the intake smoke tested.

I had also read it could be an exhaust leak near the first O2 sensor on bank one.

Anybody have any suggestions?

Black smoke at exhaust and lean code leads me to believe you have a misfire on the suspected bank.

Misfire will always read as lean by the O2 sensor and dumps unburned fuel into the exhaust as well as increase fuel to the working cylinders in that bank because it believes it is running lean. Remember O2 sensors read oxygen content. A misfire dumps fuel and unburned O2 into the exhaust.

Faulty O2 sensor or exhaust leak ahead of the O2 sensor could have similar symptoms.

__________________________________________________________________

Misfiring cylinder can be related to the ignition, fuel, or mechanical.

 

[jbanks]

Wouldn't misfile show a code? I was really hoping for another code when I went and got it read....

I forgot to mention that I sprayed carb cleaner around the intake manifold gasket to see if I could get it to affect the idle....but no luck...

I have bought plugs and coil boots that I never installed.

But, it runs so good....no hesitation or anything drive-ability related that I can tell. Not Drama at all... Only the CEL and black smoke....

 

[BANGEREXPO76]

Your on the right track with the O2 sensors.
Also make sure your PCV hose connections are all still plugged n nice and snug.

 

[rydnlow]

Is it still running good? Have you done a tune up on it yet? Have you washed the engine bay recently?

 

[1997SCEBFEX]

Wouldn't misfile show a code? But, it runs so good....no hesitation or anything drive-ability related that I can tell. Not Drama at all... Only the CEL and black smoke....

When mine ejected, then ingested the #3 plug back almost two years ago, you'd of thought that would have induced a CEL too, nada.

You're on the right track by the above posts.

PanHandler

 

[toms89]

Wouldn't misfile show a code?

Unfortunately not. Certain criteria has to be met for the pcm to recognize misfire and set code and it does not always set codes. Yes misfire can set code but not necessarily so.

 

[jbanks]

Here's an update. I'm not sure it's fixed....but....

I changed the fuel filter Saturday. I had bought it for maintenance but never put it in. New Motorcraft filter.

The filter I took out was Motorcraft and I know the previous owner hadn't had it at the dealer in years. Nothing dramatic poured out of the old filter. I had seen some people pouring black junk out of the old filter. But, I got nothing but clean fuel out of both ends.

I didn't get a chance to test drive it. But, this morning I drove it to work and thought it felt a little more lively and not as scary accelerating to merge onto the highway.

The navigator has the fuel mileage indicator on the roof and it has always read about 12 or max or 12.4 this morning when I got to work(about 30 miles) it ready 13.7 - Woo hoo

But I'm not calling it fixed yet. It took 500 miles for the CEL to come on last time. No more black smoke at Idle though....