Question about Ford Cars & Trucks
Having #1 and #2 misfires.Having Lackof upstream heatedO2 sensor switch. Sensor indicates Lean-Bank #1
Normal fuel pressure at idle is 30-40 psi. You should be able to disconnect the vac line to the regulator and see pressure go up.
If you think pressure is low, the fuel filter would be the first suspect.
The pressure regulator could also be faulty.
Posted on Dec 09, 2012
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Posted on Jan 02, 2017
I have a ford 2003 windstar that was running very rough when cold and almost stalling. engine light came on. went to autozone and they read the codes for free and told me it was running lean on Bank 2 also. i came home searched for the O2 front sensors online using the info autozone gave me. there are 2 front sensors on my car that need to be replaced at the same time. look for ones that have a direct plug in and don't need wire splicing. the ones without the wiring harness are cheaper but more of a pain, i think.
they were fairly easy to replace. getting access with the wrench was the worst. reset the light by disconnecting the battery for a few minutes. seems fine now and the light hasn't come back on.
Posted on Jan 25, 2009
if sensor indicates lean check the fuel trim if long term fuel trim is above +7 them test sensor with a piko lab scope or watch scan data and create a rich condtion by snping the throttle wide open and watch the sensor if it start to read around 700to 900mv its ok, then create a vacume leak and the sensor should read 100to 300mv i your sensor is in this range quickly its good with in 1to2 sec.
Posted on Mar 22, 2009
oxygen sensor, vacuum leak, and yes it could most definitly be if you swaped the wires of the firing order accidently you will get a code p0171 Check the tubing going from the air filter to the intake manifold to see if it has come loose. This might account for extra air going into the intake manifold than the computer is aware of. Otherwise it may be due to a faulty(or dirty) MAP/MAF sensor. Another possible cause is from low fuel pressure due to restricted fuel lines or a bad fuel pump.
Posted on Jul 28, 2009
SOURCE: ford f150 2003 po171 always
Code Po171 indicates a lean condition on cylinder bank #1 of the engine. This is the drivers side of the engine. I would suggest replacing both front oxygen sensors as a pair to start. An oxygen sensor has a life span of about 5 years and yours are now 9 years old if they are original. When they get older they are slow to respond to changes in the oxygen content of the exhaust and can trigger a code Po171. If you continue to have the same code set after the replacement of both oxygen sensors then it is time to find out why your engine is running lean. Some of the most common causes are an ignition misfire and a vacuum leak. I have also seen Fords EGR flow sensor (known by Ford as Delta Pressure Feedback sensor) to cause problems like that as well. A good mechanic with a scan tool can usually spot a problem like that in a few minutes.
Posted on Mar 01, 2011
SOURCE: check engine light code P0171
That code is a good O2 sensor reporting a lean condition. Lazy people and part stored just say it is the O2 sensor because they don't know how to fix it. Bank 1 is the side of the engine with the number one cylinder. That bank has a lean condition meaning it doesn't have enough fuel for the given amount of air. Since this is only affecting one side of the engine, that narrows down possible causes. Possible causes would a leaking intake gasket or a broken vacuum hose on that side. Since both sides get fuel from the same pump and rail, this wouldn't be a fuel pump or regulator issue. It can, however, be an indication of a bad fuel injector on that side of the engine. The MAP sensor also couldn't cause this code because, just like the fuel pump, that MAP sensor works for both sides of the engine and the code is only for one side. I would drive it for a couple more days to see if you get any additional codes that could help point you towards the actual problem. In the meantime, I would check for vacuum leaks (look at the rubber hoses and listen for high pitch hissing or sucking sounds.)
Posted on Mar 03, 2011
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