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Hard Starting, Poor Driveability, P0171

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  #1 (permalink)  
Old 20 Mar 2011, 11:48 pm
Fresh Cruiser
Join Date: Mar 2011
Location: Washington, Missouri
Posts: 8
Default Hard Starting, Poor Driveability, P0171

I searched the forum for an answer but the standard reply for code P0171 lists a number of possible reasons, but no diagnostic information.

Is there anywhere I can find out how to diagnose the problem instead of throwing parts at it? I replaced the two oxygen sensor, but there has been little or no improvement.

I have new plugs and plug wires that I will put on tomorrow, the next thing I will try is the MAP sensor, then the Idle Air Control Valve. The throttle position sensor appears to be working, it goes from 15% to about 80% from closed to open. Is this the correct range? If not can it be adjusted and how? My scan tool can read some data from the sensors, but I don't know what the values should be. The Haynes repair manual I bought for it is worthless for diagnostics, it just shows how to replace parts.

When starting, it will start then stall with my foot off the gas pedal. If I feather the throttle I can get it to start and it will idle, but it tends to bog out around 3000 rpm if I floor the throttle. I haven't driven it on the interstate, so I don't know how it will behave at high speeds. I've only had it up to around 60 and it does OK. When taking off from a stop you need to bring up the revs and slip the clutch a bit. I cleaned the idle air control valve and the piston in it moves freely, but it didn't help. I also checked for vacuum leaks, but there weren't any obvious ones.

Can anyone help me? The car is a 2006 base model convertible, with an X code engine and 5 speed manual transmission and 113,000 miles on it. I replaced the fuel pump on it last year.
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Old 02 Apr 2011, 09:39 pm
Fresh Cruiser
Join Date: Mar 2011
Location: Washington, Missouri
Posts: 8
Default Re: Hard Starting, Poor Driveability, P0171

Against my better judgment I started replacing parts, New oxygen sensors, new plugs and wires, Idle Air Control valve and MAP sensor. None fixed the problem. I have been driving the car since the problem started (It's my wife's car) and the drill to start it is to turn the key once, then the second time it starts to fire, but won't start. After several tries and pumping the gas peddle to get it to keep running and raise the and revs to 2000-3000 RPM, keep it running for a minute or two and it will idle on its own. Then when driving use only part throttle to accelerate. With 1/2 or more throttle it will start to bog down and backfire, but it doesn't give any misfire codes. It acts a lot like a carbureted car with a bad accelerator pump. I can drive on the interstate but it will not keep up on the hills, as the engine bogs down when the peddle is pushed too far down.

I cleared the code on Thursday and drove the car on Friday. The light didn't come back on but it had three pending codes:

P0133 Oxygen (Lambda) Sensor B1 S1: Response too Slow
P0171 Fuel Trim; Bank 1: System Too Lean
P2096 Post-Catalyst Oxygen (Lambda) Sensor Correction; Bank 1: Too Lean

The freeze frame info is posted below:

Freeze Frame Data for address 7E8
PID02 DTC that caused freeze frame data storage: P0171
PID03 Fuel system 1/2 status: Closed loop, using O2 sensors
PID04 Calculated load value: 52.5 %
PID05 Engine coolant temperature: 92 C
PID06 Short Term Trim - Bank 1: 32.8 %
PID07 Long Term Trim - Bank 1: 32.8 %
PID11 Intake Manifold Absolute Pressure: 45 kPa abs
PID12 Engine RPM: 3000 /min
PID13 Vehicle speed: 123 km/h
PID14 Ignition timing advance for cyl #1: 42.0 Degrees
PID15 Intake air temperature: 3 C
PID17 Throttle position sensor: 28.2 %
PID31 Time since engine start: 1248 s

I collected some log data while driving it around and it appears that the oxygen sensors drop to 0.015V when it bogs out or it could also be 0V or 0.035V. When Running OK it looks like the voltage is <0.500, but I'm not sure as I couldn't look at the data while I was driving.

Anyone have any suggestions? Does anyone know what the oxygen sensors should be reading when driving?

Thanks for any help you can provide.
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Old 02 Apr 2011, 09:50 pm
Fresh Cruiser
Join Date: Feb 2011
Location: Greenwood, Ar
Posts: 12
Default Re: Hard Starting, Poor Driveability, P0171

Maybe the fuel filter or injectors are clogged?

Did you or your wife run it completely out of gas recently?
Could have sucked a bunch of trash up in the lines.

Last edited by loadedchainsaw; 02 Apr 2011 at 09:55 pm.
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Old 02 Apr 2011, 10:04 pm
Obsessed Cruiser
Join Date: Sep 2001
Posts: 27,747
Default Re: Hard Starting, Poor Driveability, P0171

I agree with chainsaw, sounds like a fuel problem. First let me say that when the engine bogs down at 3000 rpm, it's supposed to do that. The PT has a limiter that doesn't allow you to rev the engine when sitting at idle. It's normal.

I found this from which is a paid site. You've done some of the things already.

P0171 - 1/1 Fuel System Lean - A lean air/fuel mixture has been indicated by an abnormally rich correction factor.

There are a number of possible causes including:

Restricted Fuel Supply Line
Fuel Pump Inlet Strainer Plugged
Fuel Pump Module
O2 Sensor
O2 Signal Circuit
O2 Return Circuit
O2 Sensor Heater Operation
Throttle Position Sensor Sweep
MAP Sensor Operation
ECT Sensor Operation
Engine Mechanical Problem
Fuel Contamination/Exhaust Leak

The majority of tests performed to rule out each component require the use of a DRB III scan tool and or special equipment which most owners do not have, therefore your ability to DIY will be limited. However the diagnostic that I provided will give you some idea on which areas to focus on.
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Old 12 Apr 2011, 06:54 pm
Fresh Cruiser
Join Date: Mar 2011
Location: Washington, Missouri
Posts: 8
Default Re: Hard Starting, Poor Driveability, P0171

I finally got the car fixed. Here is what I did. With it being most likely a fuel problem I needed to check the fuel pressure but there wasn't a Schroeder valve on the fuel rail. Did they deleted this on the 2006 model to save money? Anyway, I was able to disconnect the fuel line on the fire wall and connect a hose to the fuel line and there was < 10psi, where there should be 50psi. So I dropped the fuel tank and tested the pump assembly. Almost no pressure at the fitting coming out of the tank but the pump was running. So I removed the pump assembly and tested the pump. I got 70psi dead heading and 30psi with flow. Next I inspected the hose connecting the pump to the assembly and found a hole in it, in the intrados of the 180 bend. This was the new hose that came with the fuel pump when I replaced it last year, apparently a defective part. I bought a section of fuel injection hose at the parts store and replaced it and now the car runs fine.

Thanks for your help, I hope this helps someone else that has a similar problem.
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Old 13 Apr 2011, 12:43 am
Cool Cruiser
Join Date: Sep 2009
Location: Formerly NawLins
Posts: 246
Default Re: Hard Starting, Poor Driveability, P0171

Glad it was sooooooooooo .... eeeeeeeeeerrrrr ..... easy to find the problem. Good thing you had already been inside the tank and knew what it should look like.

12 Regal Turbo
06 PT - Base with BLING! TRADED 5/27/13
01 PT LE - Kid's Car - TRADED 01/13
01 Beetle Sport - SilverSport - 150+ MPH
93 Del Sol - 32+ MPG
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73 Mach1
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