obdII p0171, 1996 volvo 850 Non turbo

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1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
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izcali
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obdII p0171, 1996 volvo 850 Non turbo

Postby izcali » Thu Feb 14, 2008 10:30 pm

Hello, I have been working on my 96 volvo 850 for days without any success. I keep getting code: P0171 running lean.
problem: P0171---- unstable idle---------The vehicle runs ok while driving but when I get to an intersection, the car sitting there at idle, the engines begins to idle up and down and then gets ok, and the check engine light is on.
I have done the trying to fix the problem:
Replaced the front O2 sensor.
Cleaned the throttle system really good using a toohbrush.
Checked the distributor.
Replaced all the spark plugs.
Check the fuel pressure with a reading of 44 PSI.
Checked for any vaccum leaks spraying propane gas around all the hoses and found no leaks.
Replaced MAF sensor and a few hoses around there including the trap valve.
Using Premium gas 93.
Cleaned the Idle Air Control valve and the two hoses that go in and out of it.
Checked the vacuum hoses as well as the vacuum tree. Even the hoses under the thermostat on the intake manifold, and the one going to the fuel pressure regulator.

THE CHECK ENGINE LIGHT KEEPS COMING ON AND THE IDLE IS STILL UNSTABLE.

ANY SUGGESTIONS PLEASE!!!!!!!!!!!!

MadeInJapan
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Postby MadeInJapan » Thu Feb 14, 2008 11:34 pm

I guess what you have left then is making sure your fuel filter is clean and then that you have enough fuel pressure. Other than that, the MAF could be bad to begin with or the 02 sensor. Did you replace with OEM parts?
'98 S70 T5 Emrld Grn Met/Beige Tons of Upgrades Mobil-1
'04 V70 2.5T Red/Taupe Some Upgrades Mobil-1
'07 S40 T5 AWD 6 speed manual! Silver/Black Stage1 Heico & Elevate
'07 S60 2.5T Blue/Taupe- my kid's Volvo

izcali
Posts: 4
Joined: Mon Feb 11, 2008 1:04 pm
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p0171, 1996 volvo 850

Postby izcali » Fri Feb 15, 2008 12:56 am

I have replaced the fuel filter, and the MAF was an after market unit. But Would I be getting a different codes if in fact the MAF was going bad:
P0100 Mass or Volume Air Flow Circuit Malfunction
P0101 Mass or Volume Air Flow Circuit Range/Performance Problem
P0102 Mass or Volume Air Flow Circuit Low Input
P0103 Mass or Volume Air Flow Circuit High Input
P0104 Mass or Volume Air Flow Circuit Intermittent

The code I am getting is p0171 and none of thew above.


thanks

Ozark Lee
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Postby Ozark Lee » Fri Feb 15, 2008 1:35 am

The AMM/MAF codes can be deceptive and they will show up as O2 sensor range errors if the MAF doesn't quit altogether. It is a "goesinta" vs. "goesouta" thing. Many a time a MAF problem will throw an O2 sensor range error since it is trying to use the MAF as its benchmark to measure from.

If you still have your old MAF around try to clean it and put it back on. Use electrical contact or MAF cleaner on it. Just spray it and let it dry. Don't scrub it or even touch it.

...Lee
'94 850 N/A 5 speed
'96 Platinum Edition Turbo
'99 V70XC - Nautic Blue
Previous:
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

MadeInJapan
MVS Moderator
Posts: 12935
Joined: Thu Mar 31, 2005 2:14 pm
Year and Model: '98 S70 T5 '07S40T5
Location: Knoxville, TN American but born in Japan
Flag: United States of America

Postby MadeInJapan » Fri Feb 15, 2008 2:18 am

Another thought...if it is the MAF then just unplugging it and clearing the code and then starting your car will give you other trouble codes but not the one you were getting.
'98 S70 T5 Emrld Grn Met/Beige Tons of Upgrades Mobil-1
'04 V70 2.5T Red/Taupe Some Upgrades Mobil-1
'07 S40 T5 AWD 6 speed manual! Silver/Black Stage1 Heico & Elevate
'07 S60 2.5T Blue/Taupe- my kid's Volvo


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