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03 sxt stock p0171


 
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350boatracing
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Age: 31
Joined: 25 Dec 2016
Posts: 2
Location: Pa



Post: #1   PostPosted: Sun Dec 25, 2016 3:46 pm    Post subject: 03 sxt stock p0171 Reply with quote

Hello, I'm new here. I read through all the posts I seen here related to the p0171.

The code has been on since I got the car a couple months ago. My fuel trims are normal at idle. When I do a snap throttle test in park the trims aren't too bad. If I snap a few times in a row real fast I can see the positive fuel trim max out for a second.

Now when I drive the car down the road the positive fuel trims max out starting at light acceleration and the whole time while driving except at idle in drive.

I checked fuel pressure (with the schrader valve in the fuel rail) in park. The fuel pressure sits somewhere around 50 to 53 psi. When I snap throttle The pressure drops a couple psi and then rises a couple psi above the starting point and then back to the starting point all within a second or two. The garage told me the p0171 was due to fuel pressure but I think they said that because with car off the pressure bleeds off fairly quick. Although the car NEVER hesitates to start back up instantly.

I may give the car a false lean at idle in park via upstream o2 sensor and throttle it to hopefully simulate a load and see if pressure keeps up to the demand of extended pulse width of the injectors but all along I haven't believed it to be a fuel delivery issue.

Any thoughts?

Also the tail pipe has enough carbon for me to believe it is running on the richer side although the spark plugs give me very little if any indication of this.
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occasional demons
Mr One World
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Age: 51
Joined: 03 May 2007
Posts: 19781
Location: Ashland, Ohio

2001 Dodge Neon ES

Post: #2   PostPosted: Tue Dec 27, 2016 8:19 am    Post subject: Reply with quote

How many miles on the o2 sensor?

Have you pulled the injectors to see what kind of spray pattern they have?

Checked for vacuum leaks at the injector or o-rings, or manifold to head o-ring gaskets?

Any cracks/leaks at the exhaust manifold?
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2001 neon ES MTX with '02 R/T PCM
1999 neon 2.4 EDZ MTX
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350boatracing
n00b


Age: 31
Joined: 25 Dec 2016
Posts: 2
Location: Pa



Post: #3   PostPosted: Wed Dec 28, 2016 4:19 pm    Post subject: Reply with quote

The car has around 86000 on it and its a chrysler oxygen sensor so I think that's how many miles are on the sensor although it looks pretty clean for that mileage so I don't know for sure if it was replaced or not.

I did a pressure balance test (meaning I pressurized the fuel system and stuck an electronic pulser on each injector) on the injectors and they all checked out good.

I also checked for vacuum leaks using propane and water.

I have not checked for cracks at the manifold yet.
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