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1997 explorer 5.0 V8 missing intake vacuum hose errati idle hissing sound code P0171

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Old 04-17-2010, 11:55 PM   #1
98 5.0 awd
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1997 explorer 5.0 V8 missing intake vacuum hose errati idle hissing sound code P0171

Hi I need help finding a missing vacuum hose! I had codes P0171 PO174 idling from 500rpm to 1500rpm erratically, hissing sound under the hood, found open port on intake manifold on the driver side upper intake manifold there is a "T" fitting one line goes to the PVC valve, and the other side goes to were??? I see no line, and have plugged it with t 90 degree spark plug boot and a bolt, so far idles normally hasn't reset check engine light.. but were and what dies the missing vacuum line do, and go to?

Here is the best diagram the dealer could find me!

and here is a video of were the line is! Please help I am puzzled, so is the dealership!! thanks guys -Jamie
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Old 04-18-2010, 02:25 AM   #2
Stephens City,VA
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Yeah its just capped off bud.checked friends 98 mountaineer and his doesn't even have the t fitting just the one out back to pvc.capped mine 6 months ago no problems.hope this helps
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Old 04-18-2010, 01:51 PM   #3
yellow coupe
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I have a 97 Mountaineer AWD. That hose goes to the front of the engine and tees off to 2 smaller hoses. 1 going to the passenger side and 1 to the driver side. Not sure what they go to though. The 1 on the driver side goes under the battery tray and the 1 on the passenger side goes under the air filter box. Hope this helps you some anyway.
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Old 05-19-2010, 10:56 PM   #4
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Dk Exp Omg!

Is that the definitive answer? Because I have the EXACT SAME PROBLEM! LMAO! I could not believe I found this post! And with the drawing and everything. I have to say I am impressed!

I have a 98 Explorer AWD with the same damn problem P0174s and P0171s.

I did plugs and wires which got rid of the P0171, but even though I capped it off (the tube missing a hose in the picture) I am still getting a rough idle and feeling of lost power and mpg...sigh... Very frustrating.

Getting ready to go camping for Memorial Day and would like to get this rectified! :-) Anyone else have any ideas on this one?

I may take it over and have the guy in the next town over take a look at er. If I do I will let you know how it turns out. ;-)
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Old 05-20-2010, 06:32 AM   #5
Greenville, SC
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Vacuum reservoir & fuel VMV

I don't know about the 5.0 V8 but on my SOHC V6 there is a vacuum reservoir on the passenger side located under the air filter housing support and a fuel vapor management valve on the passenger sided under the battery support. Both of these need a manifold vacuum source.
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Old 07-29-2010, 07:02 PM   #6
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Does anyone have an update on this?

I had whatever was on that port blow off while I was in Florida. I put duct tape over it for the drive back home. When I got it in the garage I looked over it thoroughly and couldn't find any hose that used to be there so I capped it with a vacuum cap. I cleared the check engine light and that hasn't come back.

My truck is a 97 5.0 AWD. My father's 95 5.0 2WD has a hose from that port going to the front of the truck, but that hose on mine goes under the upper intake and was connected to something toward the back of the engine. I pulled on it and it definitely was not loose. He also had different connections under the front of the upper intake manifold. I don't know if that is a model year variation, an AWD vs. RWD variation, or both.

Now at Interstate speeds (65+) if I go WOT, the truck will downshift like normal, but the proceeding upshift is very hard like I have some sort of redneck shift kit on my car (which I don't like at all and it feels like it is going to break something) so I'm guessing there was a hose on that port and it provided feedback to the transmission.

Any info would be appreciated.
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Old 08-27-2011, 11:57 AM   #7
Mokena IL
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US Anyone have a definitive answer?

Well, first I thought I was going nuts...then I found this thread.
I have the exact same difficulty as the above posters' video shows. Heck, it even looks like he videotaped MY truck...

I guess where I'm confused is that I couldn't imagine an engineer putting in a vacuum line that's just going to get capped off. Am I missing something here?

Hoping someone has found a good answer from their favorite trusted Ford guy (or gal, as it may be). I'd hate to spend a few hundred bucks to let someone tell me that they just capped it off.

Thanks all in advance.
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Old 09-27-2011, 01:40 PM   #8
Amarillo, Texas
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My explorer is missing the driver's side line that goes underneath the battery. Its losing power going up hills and is idling extremely rough. Does anyone know that part number or what exactly it goes to??
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