Ranger p0171 help - shop cant fix it

[nomoredan]

I have a 1997 Ford Ranger 4cyl 2.3L motor. It has about 104,000 mi on it and it has been maintained quite well since I've had it (bought it when it had 80k).

Recently it broke down on the high way. It sputtered in idle and would stop, when I would get running to move forward it would only do so for a short period of time and then die. I ran an OBD II on it from the Autozone across the street and 2 codes came up P0171 and I forget what the other one was (should have written it down I know). I changed the fuel filter out thinking it might be a fuel problem but it did not work. I had the vehicle towed to a shop where they replace the MAF sensor. The shop tested the vehicle with the new MAF sensor and the MAF shorted out. They then put a new computer in the truck (new one with the correct software from the ford website) and an additional MAF sensor.

As soon as I drove it out of the shop the check engine light came on again. I took it back and the code P0171 showed up again (and was the only code). He said it might be due to the very cold weather (Chicago area). He said to bring it back if it still has problems.

I've already spent $650 getting it fixed.

The truck ran fine for about 150 miles and now it is doing the same thing again. The mechanic checked the truck and said the fuel pressure was right. What could this possibly be?

 

[Dragonclaw]

Check your vacuum and PCV hoses. Vacuum Hose Guide

Also have you changed the O2 sensors? I believe this is supposed to be done at 100k Miles.

 

[rurouni20xx]

did they tell you what p0171 was? its a code it means something once you kno what i translates to you can start from there.

 

[SMTGREG]

P0171 is the o2 sensor is indicating a lean condition. It could be a Vacuum leak. Exhaust leak before the 02 sensor, Bad 02 or MAF sensor including wireing. Low fuel pressure or volume. Are there any modifications to the truck? You say It's doing the same thing. Does that mean it's not running or running very bad. Try disconnecting the battery for 5 min and restart. Does it still run bad, Light come on? Another thing to try is disconnect the MAF then restart the truck. Does it run better?

 

[rockwerks]

P0171 is the o2 sensor is indicating a lean condition. It could be a Vacuum leak. Exhaust leak before the 02 sensor, Bad 02 or MAF sensor including wireing. Low fuel pressure or volume. Are there any modifications to the truck? You say It's doing the same thing. Does that mean it's not running or running very bad. Try disconnecting the battery for 5 min and restart. Does it still run bad, Light come on? Another thing to try is disconnect the MAF then restart the truck. Does it run better?

found this:

Code Po171 indicates a lean condition on cylinder bank #1 of the engine. On your Expedition this is the drivers side of the engine. I don't know what your mechanics have already done, but 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.

 

[evanq22]

Not to resurrect an old forum but i have a 1997 Ranger with a 2.3l with 222200 miles, i have the dreaded p0171 code. i’ve replaced the fuel pump, fuel filter, fuel injectors, fuel pressure regulator, the maf, pcv valve, egr, dpfe sensor, as well as both 02 sensors and checked for vacuum leaks with a vacuum tester and everything shows up fine even when i look at the live data. i’m about ready to just park it and forget about it at this point, unless someone else has further knowledge on this.