Mechanics

P0171 CODE

2000 Ford Ranger

Engine Performance problem
2000 Ford Ranger 4 cyl Two Wheel Drive Automatic 60000 miles

P0171 code came back after a week when I changed vacuum hose and changed MAF sensor. Have checked for
Vac leaks cant find one. I did buy a new code reader ( equus Innova 3140 do have the freeze frame and live data recorded Hope this will get me closer to solving the problem.
Dtc for which Freeze frame was stored. P0171
fuel system 1 status Closed loop
fuel system 2 status not supported
Calculated load value 36.86%
coolant temp 82 c
short term fuel trim 7.03 %
long term fuel trim 25.00%
engine rpm 1846 rpm
vehicle speed 46 mph



live data

fuel system 1 CL
calculated load value 29.41 %
coolant temp 87.00 c
short term fuel trim -0.78
long term fuel trim 2.34
engine rpm 952.25
vehicle speed sensor 0.00
ignition timing advance#1 cylinder 6.50
Air flow rate from Mass air flow sensor 4.06 g/s
absolute throttle position 17.25
bank 1 sensor 1 0.76 V
Bank 1 sensor 1 -2.34 %
Bank 1 sensor 2 0.82

OBD II


2.5 engine
New to this Obd II so really don't know what this all means. Can you help out?
Avatar
Wheelchairdude49
September 18, 2010.




Hello,

Thank You for the Donation.....

A P0171 lean code for bank 1 is the cylinder bank on the RIGHT (passenger) side of the engine on Ford vehicles with a V6 or V8 engine.

A lean fuel condition may exist if the engine is sucking in too much air and/or the fuel system is not delivering enough fuel. If bad enough, a lean fuel condition may cause lean misfire, a rough idle, hesitation or stumble when accelerating, and/or poor engine performance.

Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor that is not reading airflow accurately, an EGR valve is not closing and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow (because the EGR differential pressure sensor that monitors EGR flow is faulty and is under-reporting EGR flow).

If the problem is not enough fuel, the underling cause may be a weak fuel pump, restricted fuel filter, leaky fuel pressure regulator or dirty fuel injectors. Will need to check fuel pressure...

Ford p0171 AND p0174 lean codes can also be set by a bad EGR differential pressure sensor. These sensors have a very high failure rate once a vehicle has more than about 60,000 miles on the odometer or is more than five or six years old.


http://www.aa1car.com/library/s_ford_dpfe_sensor_1.jpg



The DPFE sensor is mounted on the engine, and is attached with two rubber hoses to the tube that routes exhaust gas to the EGR valve. The original equipment sensor has an rectangular aluminum housing about three inches long. Corrosion inside the sensor reduces its sensitivity to EGR flow, causing it to under-report EGR flow. The PCM responds by increasing EGR flow, which may keep the EGR valve open longer than usual creating a lean condition in the engine. Thus, a bad sensor may set a P0401 code (insufficient EGR flow), or it may not set an EGR code but a P0171 and/or P0174 lean code instead.

The cause of the P0401 code in most cases turns out to be a bad DPFE sensor, not an EGR valve problem or an EGR valve that is plugged up with carbon (though this can also set a P0401 code). An aftermarket replacement DPFE sensor costs less than $50 and usually gets rid of not only the P0401 code, but also the P0171 and P0174 codes, too.

.

Obxautomedic
Sep 18, 2010.
Also, Check pcv hose rubber connector at valve cover and at throttle body for vacuum leak.

Also, Does the Heater Control work properly?

.

Obxautomedic
Sep 18, 2010.
New hose on valve cover to throttle body. Was one of 2 hoses I changed. Heater control works fine.

Tiny
Wheelchairdude49
Sep 18, 2010.
Sorry for delay.

Have you checked or changed the EGR differential pressure sensor?

These sensors have a very high failure rate once a vehicle has more than about 60,000 miles on the odometer or is more than five or six years old.

.

Obxautomedic
Sep 21, 2010.
Not yet. Just put another new Maf sensor on it yesterday and a new pcv and hose changed the fuel filter too. Still got the code coming back. Will try that next ( dpfe)

Tiny
Wheelchairdude49
Sep 21, 2010.
ERASE THE KAM. Do this by disconnecting the battery for 30 minutes. Hook up and hook up scan tool then start vehicle. Look at the shrt term and long term fuel trims if they immediately start steadily climbing up begin to bring the vehicle off of idle up to around 2500 rpms. Do the fuel trims stay high or do they start to slowly go down to around -5 to 8 on short term?

Blackop555
Sep 27, 2010.
Just finished erasing the KAM. Short term fuel trims
@2500rpm Got as high as 8.5 lowered to, 7.0, 1.5,
3.1 4.6, 0.7 - 0.7, -1.5, 2.3, -3.1, 1.5 -2.1.
Long term stayed right at 3.9

Tiny
Wheelchairdude49
Sep 28, 2010.
What was the fuel trims at idle?

Blackop555
Sep 28, 2010.
Short 8.5, 7.0, 1.5, 3.1, 4.6, 0.7, -0.7
long term anywhere from 0 to 3.1
AD

Tiny
Wheelchairdude49
Sep 28, 2010.
Is the code still coming back? With the info you gave me there doesnt appear to be a problem that would throw the code.

Blackop555
Sep 28, 2010.

AD