Question about 1998 Ford Escort

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98 escort ZX2 code P0171. cleaned the MAF sensor and changed the coolant sensor. ran a whole lot better but not perfect and slowly went downhill again. dies at stop light and engine rpms change. So I changed out the MAF with a Cardone reman and only a little better. drove the car for 80 miles and code came back up again. only the P0171 code in the system.

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  • Anonymous Mar 22, 2014

    trouble code P0171

  • Anonymous Mar 22, 2014

    trouble code P0171



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Brad Kirby

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System Too Lean (Bank 1) Symptoms include stalling at idle, rough idle, poor MPG, loss of power, high pitch sucking sound from the engine bay. This is typically caused by a vacuum leak. The most common cause is a hole in the elbow at the PCV valve. It may be hard to see so you'll want to pull it out to check it. Also look at the elbow that connects the PCV hose to the intake manifold. It can get a hole there as well. This is 90% caused by a vacuum leak and not the O2 sensor. Most people (ignorant ones) will just say it is the sensor because it set the code. That code is a good sensor reporting a lean condition. Just replacing the sensor without checking for other problems first would be like replacing an entire wire harness when a light goes out instead of checking the bulb and fuse first. Other causes can be a bad sensor, bad MAF, low fuel pressure, or an exhaust leak. To fix the elbows on the PCV valve you can pick up new ones from the HELP section of the local part store. The part numbers for the elbows from the Help section are:
The one that goes on the intake manifold fits the nipple on the manifold snugly. But, it doesn't fit snug on the line so you'll need to use a clamp on that part. The one on the PCV valve is a very tight fit at both ends. If you don't want to bother trying to rig this up, you can purchase a new line from Ford. The part number is: F8CZ-6853-CA.

Posted on Mar 05, 2010


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Ford escort zx2 code po171

What is model year? How long since a tune-up?
With idle issues, check and clean idle air system, see if it helps? Use a gage and check proper fuel pressure, key on engine off. On some ford vehicles, with everything off, unplug the maf sensor, where applicable, take the vehicle for a spin, if it does a lot better, have to check the maf system, that includes, sensor--wiring circuits--pcm.
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P0171 is O2 sensor indicates lean. You probably have a vacuum leak. The most likely and common cause is the PCV elbow at the front of the engine.

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My name is Shawn and I have a 2001 toyota corolla. I just replaced the front oxygen sensor,coolant temp sensor and new plugs. But still my engine light is coming on with a P0171 engine to lean code. What...

P0171 means Fuel Trim System Lean (Bank 1)

The MAF (Mass Air Flow) Sensor is dirty or faulty.

Note: The use of "oiled" air filters (K&N, etc.) can cause the MAF to become dirty if the filter is over-oiled

There could be a vacuum leak downstream of the MAF sensor.

If your FT is leaning it that much, I would suspect an O2 sensor or it's circuit is the problem. When that O2 sensor went to 2V, I think you found your problem. The O2S is telling the PCM that the fuel ratio is way rich, so the PCM is assigning a way lean fuel trim.

Replacing the Mass Air Flow Sensor should do the trick.

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Trouble code p0134 and p0171

A code P0134 may mean that one or more of the following has happened:
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  • Bad heater circuit in the O2 sensor
  • Wiring or connector to the sensor frayed / broken
  • Blown heater circuit fuse
  • Holes in the exhaust system
  • PCM failure
Possible Solutions The most common fix is to replace the oxygen sensor. But that doesn't rule out the possibility of:
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  • Inspect wiring & connector(s) for problems
  • Excessive amperage blowing heater fuse (still requires replacement of sensor but also replacement of blown fuse)
  • Replace PCM (only as last resort after all other possibilities are covered.
A code P0171 may mean that one or more of the following has happened:
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  • There could be a vacuum leak downstream of the MAF sensor.
Possible Solutions Possible solutions include:
  • In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
  • Inspect all vacuum and PCV hoses, replace if necessary
  • Check for a dirty fuel filter and proper fuel pressure

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98 ford taurus starts, runs, dies

change the coolant temp sensor and rest the codes then try
cleam the MAF by brake and parts cleaner

i hope its help thanx

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