Code P0171 - Ford Bronco Forum
 
LinkBack Thread Tools Display Modes
post #1 of 10 (permalink) Old 08-16-2018, 01:25 AM Thread Starter
Registered User
 
Hylander's Avatar
 
Join Date: May 2015
Location: Northern Ca.
Posts: 556
Bronco Info: 1996 XLT, 5.8, 4" RC Lift, Procomp 1069 16x8" Wheels, Toyo MT 285/75R16 Tires
iTrader: (0)
Garage
Code P0171

My Bronco 96, 5.8 just had the CEL come on today.
Pulled code P0171, I did clear it.
What to start checking ?
Was thinking fuel filter and 02 Sensors since they are originals and have never been replaced.
Will also check for vacuum leaks.

Failure is not an Option.
Hylander is offline  
Sponsored Links
Advertisement
 
post #2 of 10 (permalink) Old 08-16-2018, 01:27 AM
Registered User
 
95bronco460's Avatar
 
Join Date: Apr 2014
Location: Nampa, ID
Posts: 164
Bronco Info: 95 Eddie Bauer MAF 466/E40D, Dana 60 Front, Sterling 10.25 rear, 5.13 Gears, Custom Exhaust ETC..
iTrader: (0)
Quote:
Originally Posted by Hylander View Post
My Bronco 96, 5.8 just had the CEL come on today.
Pulled code P0171, I did clear it.
What to start checking ?
Was thinking fuel filter and 02 Sensors since they are originals and have never been replaced.
Will also check for vacuum leaks.
I'd just replace the O2 sensors and clear the codes and see what happens next

Sent from my SM-G960U using Tapatalk
95bronco460 is offline  
post #3 of 10 (permalink) Old 08-16-2018, 01:31 AM Thread Starter
Registered User
 
Hylander's Avatar
 
Join Date: May 2015
Location: Northern Ca.
Posts: 556
Bronco Info: 1996 XLT, 5.8, 4" RC Lift, Procomp 1069 16x8" Wheels, Toyo MT 285/75R16 Tires
iTrader: (0)
Garage
Quote:
Originally Posted by 95bronco460 View Post
I'd just replace the O2 sensors and clear the codes and see what happens next

Sent from my SM-G960U using Tapatalk
Thanks,

I know there are 3 sensors, are they all the same ?

Failure is not an Option.
Hylander is offline  
Sponsored Links
Advertisement
 
post #4 of 10 (permalink) Old 08-16-2018, 01:37 AM
Registered User
 
95bronco460's Avatar
 
Join Date: Apr 2014
Location: Nampa, ID
Posts: 164
Bronco Info: 95 Eddie Bauer MAF 466/E40D, Dana 60 Front, Sterling 10.25 rear, 5.13 Gears, Custom Exhaust ETC..
iTrader: (0)
mm no.. they have different plugs I believe.. they're even color coded on my 96

Sent from my SM-G960U using Tapatalk
95bronco460 is offline  
post #5 of 10 (permalink) Old 08-16-2018, 09:20 AM
Moderator
 
miesk5's Avatar
 
Join Date: Oct 2003
Location: Coronado, CA
Posts: 21,905
Bronco Info: 96 Bronco XL 5.0 E4OD, Man Xfer/Hubs
iTrader: (2)
Garage
Yo Hylander,
I edited this 3 times this morning, because Comcast took a dump . I highlighted the usual easy-to-inspect or test perpetrators.

Try and figure out if your scan tool can read Parameter Identifications (PIDs); they are codes used to request data from a vehicle, used as a diagnostic tool. Typically, an automotive technician will use PIDs with a scan tool connected to the vehicle's OBD-II connector.
The technician enters the PID, the scan tool sends it to the vehicle's controller–area network (CAN)-bus, VPW, PWM, ISO, KWP. (After 2008, CAN only)
A device on the bus recognizes the PID as one it is responsible for, and reports the value for that PID to the bus
The scan tool reads the response, and displays it to the technician...
1996 5.8L E/F-Series/Bronco (E40D)
Typical Diagnostic Reference Values
DPFEGR; EEC-V Pin #65/PID only;
Measured/PID Values
KOEO 0.2-1.3;
Hot Idle 0.2-1.3;
30 MPH 0.2-4.5;
55 MPH 0.2-4.5.
Units Measured/PID; DCV (DC Volts)

This is Fords pin-point test that a Ford dealer tech would do with Ford's old Break-Out Box; so, as I mentioned in another thread here; In place of the break-out box, go to the EECV connector pin instead; Substitute EECV connector pin Number for breakout box number.

EECV Connector Pin Diagram
http://broncozone.com/uploads/monthl...1310643563.gif
Legend: IGNORE �.
Pin Number Circuit Circuit Function
1 315 (P/O) PCM to Transmission Shift Solenoid No. 2
2 658 (P/LG) PCM to Check Engine Indicator Lamp
3 Not Used
4 Not Used
5 Not Used
6 651 (BK/Y) Dedicated Ground
7 Not Used
8 Not Used
9 Not Used
10 Not Used
11 Not Used
12 Not Used
13 107 (P) PCM Flash EEPROM Power Supply
14 784 (LB/BK) 4x4 Low Range Switch to PCM Indicator Lamp
15 915 (PK/LB) J1850 Bus Negative/Data Negative (Return) to PCM
16 914 (T/O) J1850 Bus Positive/Data Positive
17 Not Used
18 Not Used
19 Not Used
20 Not Used
21 Not Used
22 Not Used
23 259 (O/R) Dedicated Ground to TFI Module
24 570 (BK/W) Dedicated Ground PCM
25 875 (BK/LB) Ground Logic Module
26 � Not Used
27 237 (O/Y) PCM to Transmission Shift Solenoid No. 1
28 � Not Used
29 224 (T/W) Transmission Overdrive Cancel Switch to PCM
30 � Not Used
31 � Not Used
32 � Not Used
33 676 (PK/O) Vehicle Speed Sensor � Negative (Return) to PCM
34 � Not Used
35 392 (P/LG) Heated Exhaust Gas Oxygen Sensor No. 3 to PCM
36 968 (T/LB) Mass Airflow Return
37 923 (O/BK) Transmission Oil Temperature to PCM
38 354 (LG/R) Engine Coolant Temperature Sensor to PCM
39 743 (GY) Air Charge Temperature Sensor to PCM
40 238 (DG/Y) Fuel Pump Monitor to PCM/Fuel Pump Relay to Safety Switch
41 198 (DG/O) A/C Pressure Switch to Control Relay
42 � Not Used
43 � Not Used
44 200 (BR) PCM to Air Management No. 2 (Was TAD)
45 � Not Used
46 � Not Used
47 360 (BR/PK) PCM to Electronic Vacuum Regulator � Constant Current
48 382 (Y/BK) PCM to Test Connector No. 2
49 395 (GY/O) Profile Ignition Pickup to PCM
50 929 (PK) PCM to Spark Angle Pulse Width/Spark Output
51 570 (BK/W) Dedicated Ground � PCM
52 � Not Used
53 924 (BR/O) PCM to Transmission Coast Clutch Solenoid
54 480 (P/Y) PCM to Transmission Converter Clutch Control
55 37 (Y) Battery to Load
56 191 (LG/BK) PCM Top Vapor Management Valve � Constant Current
57 310 (Y/R) Knock Sensor No. 1 to PCM
58 679 (GY/BK) Vehicle Speed Sensor � Positive to PCM
59 917 (DG/LG) Misfire Detection Sensor � Feed
60 74 (GY/LB) Heated Exhaust Gas Oxygen Sensor No. 1 to PCM
61 � Not Used
62 � Not Used
63 � Not Used
64 199 (LB/Y) Manual Lever Position Sensor to PCM
65 352 (BR/LG) Delta Exhaust Pressure Transducer to PCM
66 � Not Used
67 � Not Used
68 � Not Used
69 � Not Used
70 190 (W/O) PCM to Air Management No. 1 (Was TAB)
71 361 ® Power Output from PCM Relay
72 561 (T/R) PCM to Fuel Injector No. 7 Cylinder
73 559 (T/BK) PCM to Fuel Injector No. 5 Cylinder
74 557 (W) PCM to Fuel Injector No. 3 Cylinder
75 555 (T) PCM to Fuel Injector No. 1 Cylinder or Bank No. 1
76 570 (BK/W) Dedicated Ground � PCM
77 570 (BK/W) Dedicated Ground � PCM
78 � Not Used
79 911 (W/LG) PCM to Output Circuit Indicator Lamp/Overdrive Cancel Indicator
80 926 (LG/O) PCM to Fuel Pump Relay Control
81 925 (W/Y) PCM to Electronic Pressure Control No. 1
82 � Not Used
83 264 (W/LB) PCM to Idle Speed Control Motor No. 1
84 136 (DB/Y) Output Shaft Speed to PCM
85 � Not Used
86 � Not Used
87 94 (R/BK) Heated Exhaust Gas Oxygen Sensor No. 2 to PCM
88 See 967 (LB/R) Mass Air Flow Sensor to PCM
89 355 (GY/W) Throttle Position Sensor to PCM/Diesel Fuel Injector Pump Lever Sensor
90 351 (BR/W) Power to Engine Sensors
91 359 (GY/R) Sensor Signal Return
92 511 (LG) Stoplamp (Brake On/Off) Switch to Stoplamps
93 387 (R/W) HEGO Sensor Heater Voltage Monitor No. 1 to PCM
94 388 (Y/LB) HEGO Sensor Heater Voltage Monitor No. 2 to PCM
95 389 (W/BK) HEGO Sensor Heater Voltage Monitor No. 3 to PCM
96 � Not Used
97 361 ® Power Output from PCM Relay
98 562 (LB) PCM to Fuel Injector No. 8 Cylinder
99 560 (LG/O) PCM to Fuel Injector No. 6 Cylinder
100 558 (BR/LB) PCM to Fuel Injector No. 4 Cylinder
101 556 (W) PCM to Fuel Injector No. 2 Cylinder or Bank No. 2
102 � Not Used
103 570 (BK/W) Dedicated Ground � PCM
104 � Not Used

...

DTCs P0172, P0174, P0171 AND P0175: FUEL SYSTEM AT THE CORRECTED ADAPTIVE LIMITS
Diagnostic Trouble Codes (DTCs) P0171 bank (1) (cylinder #1) and DTC P0174 bank (2) indicate the fuel/air ratio is too lean.
miesk5 NOTE; FORD'S naming convention is that bank one is the same bank as where the number one cylinder is; sensor one and two are in the Y before the cat & sensor 3 is after the cat.
Source

The fuel adaptive system is at the rich correction limit. DTC P0172 bank (1) and DTC P0175 bank (2) indicate the fuel/air ratio is too rich. The fuel adaptive system is at the lean correction limit.DTCs HO2S Reference list:
HO2S-11 = DTCs P0171 and P0172
DTCs P0174 and P0175
Possible causes:Fuel system
Excessive fuel pressure.
Leaking fuel injector(s).
Leaking fuel pressure regulator. Pull vacuum hose off, any fuel or aroma, replace FPR.
Low fuel pressure.
Contaminated injector(s)
Induction system:
Air leaks after the MAF. check tubes from MAF TO TB
Vacuum leaks. See my Vacuum leak test @ https://www.fullsizebronco.com/forum...odes-idle.html ... post #11.

Restricted air inlet from atop radiator support through air filter through throttle body. Check air intake for leaks, obstructions and damage.


Fuel purge system. Check vapor cannister, hoses to Vapor Management Valve (VMV) & TB.
Improperly seated dip stick.

EGR, Leaking gasket. Stuck open EGR valve. Leaking diaphragm.

Base engine:
Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2S's.

Verify integrity of the PCV system. Check vacuum hose & valve itself.
....

Are there any of the above concerns?
Yes SERVICE as necessary. RERUN Quick Test.
No, GO to Pinpoint Test Step DC25. If MAF reading is within specification, return to Pinpoint Test Step H42. Check MAF for contamination; see below)
*** Over oiled K&N Air filters can cause this **
*

H42 INITIATE KOER SELF-TEST
Key off.
Scan Tool connected.
Disconnect fuel vapor hose from TB and plug fitting at TB.
Start engine and run at 2000 rpm for 1 minute and return to idle.
Enter Key On Engine Running (KOER) Self-Test.
Are HO2S DTCs P1127, P1128 P1129, P1131, P1132, P1151 or P1152 present?

Yes If DTC(s) P1127, P1128, or P1129 are present, GO to Section 5A, Powertrain Diagnostic Trouble Code (DTC) Charts and SERVICE those DTCs first. If DTC(s) P0131 and/or P0151 are present in Continuous Memory, SERVICE DTC P0131 or P0151 in the order they are displayed. GO to H27.

All others, GO to H43.

No For DTCs P1130, P1150, P0171, P0174, P0172 and P0175:
GO to H43.

If DTC(s) P1132 and/or P1152 are no longer present, RECONNECT fuel vapor line. GO to HW43.
All others:
The fault that produced the DTC is an intermittent. GO to Pinpoint Test Step Z1 with the following data: HO2S-11, 21 PIDs and list of Possible Causes.

H43 CHECK FUEL PRESSURE
WARNING: THE FUEL SYSTEM IS PRESSURIZED WHEN THE ENGINE IS NOT RUNNING. TO PREVENT INJURY OR FIRE, USE CAUTION WHEN WORKING ON THE FUEL SYSTEM.
Key off.
Install fuel pressure gauge.
Verify vacuum source to fuel pressure regulator.
If engine will start:
Start engine and idle. Record fuel pressure.
Increase engine speed to 2500 rpm and maintain for one minute. Record fuel pressure.

No Start:
Cycle key on and off several times. Record fuel pressure.

Is the fuel pressure between 30-45 psi (210-310 kPa)?
Yes Fuel system is capable of required fuel pressure. GO to H44.
No Fuel pressure out of specification. GO to Pinpoint Test HC.

H44 CHECK SYSTEM ABILITY TO HOLD FUEL PRESSURE
Fuel pressure gauge installed.
Cycle key on and off several times.
Verify there are no external leaks (repair as necessary).
Does the fuel pressure remain within 5 psi of the highest reading after one minute?

Yes For DTCs P1130, P1150, P0171, P0172, P0174 and P0175: GO to H45.
For No Starts: GO to H46.
For fuel control DTCs displayed with misfire DTCs: GO to H47.
All other DTCs: GO to H51.
No No Excessive pressure loss. GO to Pinpoint Test Step HC3.


H45 CHECK SYSTEM ABILITY TO HOLD FUEL PRESSURE WITH KEY ON
Fuel pressure gauge installed.
Cycle key on then off several times.
Turn key on and engine off, monitor fuel pressure gauge.
Does the fuel pressure remain within 5 psi of the highest reading after 10 seconds?
Yes For DTCs P1130, P1150, P0171 and P0174: GO to H47.
No For DTCs P0172 and P0175: GO to H49.

H46 CHECK ABILITY OF INJECTOR(S) TO DELIVER FUEL
Pressure gauge installed.
Cycle key several times.
Locate a6nd disconnect the Inertia Fuel Shutoff (IFS) Switch.
Monitor pressure gauge while cranking the engine for at least five seconds.
Was there a pressure drop greater than 5 psi (34 kPa) while cranking the engine?
Yes The EEC-V System is not the cause of the no start. REMOVE the fuel pressure gauge. RECONNECT the IFS switch. REFER to Symptom Flowcharts, Symptom Flowcharts, for further diagnosis.
No, REMOVE fuel pressure gauge. RECONNECT IFS switch. GO to H47.

H47 CHECK RESISTANCE OF INJECTOR(S) AND HARNESS
Key off.
Disconnect PCM. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Note: This erases Continuous Memory DTCs.
Install breakout box, leave PCM disconnected.
Note: If misfire DTCs are displayed with the Fuel Control DTCs, use the misfire DTCs to determine the injector circuits requiring testing.
Measure resistance between suspect injector Test Pin(s) and Test Pin 71 or 97 at the breakout box using the chart below.
Cyl# Test Pin# Cyl# Test Pin#

1 75 5 73

2 101 6 99

3 74 7 72

4 100 8 98

Is the resistance between 11.0-18.0 ohms?
Yes Fuel injector and harness resistance is OK. GO to H50. No GO to H48.

H48 CHECK CONTINUITY OF FUEL INJECTOR HARNESS
Key off.
Breakout box installed, PCM disconnected.
Disconnect injector harness connector at the suspect injector.
Measure the resistance between Test Pin 71 or 97 at the breakout box and the VPWR pin at the injector harness connector.
Measure resistance between the Injector Test Pin(s) at the breakout box and the Injector Signal Pin at the injector connector. (Refer to chart in H47 for Injector Pin location.)
JIs each resistance less than 5.0 ohms?

Yes GO to H49.
No SERVICE open harness circuit. REMOVE breakout box. RECONNECT PCM and fuel injectors. RERUN Quick Test.

H49 CHECK INJECTOR HARNESS CIRCUIT FOR SHORT TO POWER OR GROUND
Key off.
Breakout box installed, PCM disconnected.
Suspect fuel injector harness disconnected.
Measure resistance between the injector Test Pin(s) and Test Pin 71 or 97, 24, 76 and 103 at the breakout box (refer to chart in H47).
Measure the resistance between the Injector Test Pin(s) at the breakout box and chassis ground.
Is each resistance greater than 10,000 ohms?
Yes GO to H50.
No SERVICE short circuit. REMOVE breakout box. RECONNECT PCM and all fuel injector(s). RERUN Quick Test.

H50 CHECK INJECTOR DRIVER SIGNAL
Requires standard 12 volt test lamp.
Key off.
Breakout box installed.
Connect PCM to breakout box.
Connect test lamp between Test Pin 71 or 97 and each injector Test Pin (refer to chart in H47).
Crank or start engine.
Note: Properly operating system will show a dim glow at idle on the test lamp.
Does test lamp have a dim glow while cranking or running engine?
Yes REMOVE breakout box. RECONNECT PCM. GO to H51.
No, No light/Continuous bright light. REPLACE PCM. REMOVE breakout box. RERUN Quick Test.


H51 FLOW TEST FUEL INJECTOR(S)
Flow test fuel injector(s).
Use the Rotunda Injector Tester 164-R3750, SBDS Injector Tester or equivalent to flow test the injectors according to the instructions for the injector tester.
Is the leakage and flow within specification?

Yes DTCs P0171, P0172, P0174 and P0175: The fault that produced the DTC is an intermittent. GO to Pinpoint Test Step Z1 with the following data: SF1, SF2, LFT1, LFT2 PIDs and list of possible causes.
No REPLACE injector. RERUN Quick Test.


Z1 INTERMITTENT TEST PROCEDURE
Note: All Intermittent Procedures are used in conjunction with the Intermittent Symptom Charts and the Typical Diagnostic Reference Values at the end of the pinpoint.
If directed here from another pinpoint test, refer to PIDs, circuits or components that were recommended or else refer to the Symptom Chart at the end of the pinpoint for the proper selection.
Based on the Intermittent Prioritization Chart, choose an Intermittent Diagnostic Procedure below:
Input Test - This test is used on sensing devices such as temperature, position, oxygen, etc.
Output Test - This test is used on output devices such as relays, coils, solenoids, etc.
Water Soak Test - This test is used on both input and output devices. Especially useful on spark plug wires, relays and hall effect sensors.
Road Test - This test is used on both input and output devices. Four modes of engine operation are monitored for intermittent.
Note: The electronic ignition (EI) system tester is not capable of diagnosing coil on plug (COP) systems.
Ignition Test - This test is for non coil on plug only and used to diagnose the ignition system using the Electronic Ignition (EI) System Tester. Coil on plug applications will use the input, output, water soak and road test only. Select the next priority from the intermittent prioritization chart.

Have you chosen an Intermittent Diagnostic Test procedure?
Yes for the Input Test: GO Z10.
For Output Test: GO to Z20.
For Water Soak Test: GO to Z30.
For Road Test: GO to Z40.
For Ignition Test: GO to Z50.

No To diagnose other driveability symptoms, GO to Symptom Flowcharts, Symptom Flowcharts.

Z10 INTERMITTENT KOEO INPUT WIGGLE PROCEDURE
WARNING: USE CAUTION WHEN PERFORMING ANY OF THE TEST STEPS. ALWAYS BE AWARE OF HANDS, CLOTHING OR TOOLS NEAR COOLING FANS, ENGINE DRIVE BELTS OR HOT SURFACES.

Key off.
Connect Scan Tool to DLC.
Access PIDs based on information from the pinpoint test or Intermittent Symptom Charts at the end of this pinpoint test.
Go to the area of the suspected wiring or component fault.
Key on, engine off.
If input is a switch-type component, turn on manually.
Lightly tap on component while viewing PID values. Wiggle and pull each component wire (Signal, Signal Return and VREF, if applicable) at the component.
Look for abrupt changes in PID values. Compare the actual PID values to the KOEO Diagnostic Reference PID Values at the end of this pinpoint test.

Are any PID values out of range or suddenly drop out and back into range?
Yes Possible wiring or component problem. CHECK each wire for corrosion, bent or loose terminals and poor wire terminal crimps. SERVICE as necessary. Otherwise, REPLACE component. VERIFY repair. If unable to verify, REINSTALL original part and GO to Z11.
No GO to Z11 for PCM wiring check

WARNING: USE CAUTION WHEN PERFORMING ANY OF THE TEST STEPS. ALWAYS BE AWARE OF HANDS, CLOTHING OR TOOLS NEAR COOLING FANS, ENGINE DRIVE BELTS OR HOT SURFACES.

Key off.
Connect Scan Tool to DLC.
Access PIDs based on information from the pinpoint test or Intermittent Symptom Charts at the end of this pinpoint test.
Go to the area of the suspected wiring or component fault.
Key on, engine off.
If input is a switch-type component, turn on manually.
Lightly tap on component while viewing PID values. Wiggle and pull each component wire (Signal, Signal Return and VREF, if applicable) at the component.

Look for abrupt changes in PID values. Compare the actual PID values to the KOEO Diagnostic Reference PID Values at the end of this pinpoint test.

Are any PID values out of range or suddenly drop out and back into range?

Yes Possible wiring or component problem. CHECK each wire for corrosion, bent or loose terminals and poor wire terminal crimps. SERVICE as necessary. Otherwise, REPLACE component. VERIFY repair. If unable to verify, REINSTALL original part and
No GO to Z11.


Z11 INTERMITTENT KOEO INPUT WIGGLE PROCEDURE
Continue to monitor the information from the previous step.
Go to the area of the suspected wiring or component fault.
Turn ignition key to the ON position.
Wiggle and pull each sensor wire (Signal, Signal Return and VREF, if applicable) from the component back to the PCM connector.
Look for abrupt changes in PID values. Compare the actual values to the KOEO Diagnostic Reference PID Values.
Are any PID values out of range or suddenly drop out and back into range?
Yes Possible wiring or component problem. CHECK each wire for corrosion, bent or loose terminals and poor wire terminal crimps. SERVICE as necessary. Otherwise, if the value dropped out while checking the PCM harness connector and there is no evidence of a fault, REPLACE PCM. If unable to verify, REINSTALL original PCM. Return to Z1 and choose another procedure to follow. Unable to verify fault.
No GO to Z12 KOER Wiggle Test.


Z12 INTERMITTENT KOER INPUT WIGGLE PROCEDURE
WARNING: USE CAUTION WHEN PERFORMING ANY OF THE TEST STEPS. ALWAYS BE AWARE OF HANDS, CLOTHING OR TOOLS NEAR COOLING FANS, ENGINE DRIVE BELTS OR HOT SURFACES.
Key off.
Access PIDs based on information from the pinpoint test or from the Intermittent Symptom Chart.
Go to the area of the suspected wiring or component fault.
Key on, engine running.
Lightly tap on component while viewing PID values. Also wiggle and pull each component wire (Signal, Signal Return and VREF, if applicable) at the component.
Look for abrupt changes in PID values. Compare the actual values to the HOT IDLE Diagnostic Reference PID Values.
Are any PID values out of range or suddenly drop out and back into range?
Yes Possible wiring or component problem. CHECK each wire for corrosion, bent or loose terminals and poor wire terminal crimps. SERVICE as necessary. Otherwise, REPLACE component. VERIFY repair. If unable to verify, REINSTALL original part, and GO to Z13.
No GO to Z13 for PCM wiring check.

Z13 INTERMITTENT KOER INPUT WIGGLE PROCEDURE
Continue to monitor the information from the previous step.
Go to the area of the suspected wiring or component fault.
Key on, engine running.
Wiggle and pull each component wire (Signal, Signal Return and VREF, if applicable) from the component back to the PCM connector.
Look for abrupt changes in PID values. Compare the actual values to the HOT IDLE Diagnostic Reference PID Values.
Are any PID values out of range or suddenly drop out and back into range?
Yes Possible wiring or component problem. CHECK each wire for corrosion, bent or loose terminals and poor wire terminal crimps. SERVICE as necessary. Otherwise if the value dropped out while checking the PCM harness connector and there is no evidence of a wiring fault, REPLACE PCM. If unable to verify repair, REINSTALL original PCM and RETURN to Z1 and choose another procedure to follow.
No Unable to verify fault. RETURN to Z1 and choose another procedure to follow.

....


Test & Overview, W/Differential Pressure Feedback (DPFE) Sensor
by Mike N at smpcorp.com via web.archive.org
KSLOW TO LOAD, so I'll give you the text here;

MIESK5 NOTE: only 95 5.8L California models & all 96 have the DPFE Sensor instead of EGR Valve Position Sensor (EVP) & Trucks never used a Pressure Feedback Exhaust (PFE) Sensor

"...The first step is to perform a thorough visual inspection of the system. If the inspection reveals nothing obvious, then some diagnostics are in order. Install a vacuum gauge in the vacuum line between the EGR valve and the control solenoid. Next, run the Key On-Engine Running self test. At one point during the self test, the PCM will check the EGR system by applying vacuum to the EGR valve. It accomplishes this by grounding the EGR regulating solenoid at a duty cycle of approximately 30%. If you see that the vacuum gauge indicates a vacuum reading of a few inches or more, you can be sure that the PCM, wiring, vacuum lines, and the regulating solenoid are functional. If not, then you must investigate where the source of the problem lies. If you do get a vacuum signal, then, exit the self test. With the engine at idle, apply vacuum to the EGR valve with a vacuum pump. When you apply vacuum, you should notice a change in engine RPM, with the possibility that the engine may stall. If the engine RPM changes, then we know the EGR is working. If there are no changes, then either the EGR valve is not functioning, or, the EGR passages are blocked with carbon. If engine RPM does change, then our next step is to examine the DPFE (Differential Pressure Feedback) sensor. The three wires consist of a 5 volt reference (which is shared with other sensors), a sensor ground (which is also shared), and a dedicated signal or output wire which is connected to the PCM. The DPFE sensor measures the difference between the upstream pressure (exhaust side), and the downstream pressure (intake side). Both sides are separated by an orifice assembly which is a calibrated opening that exhaust gas flows through when the EGR valve opens (refer to diagram #1). The DPFE sensor should measure equal pressure on both sides with the EGR valve closed. This means that we can measure and compare the signal voltage at idle with the signal voltage at key on, engine not running. Under these two conditions, if we see a difference in voltage output, then the EGR valve must be open (normally it should not be open at idle, or, with the engine not running). When the EGR valve opens under normal conditions, the upstream pressure should begreater than the downstream pressure. If not, then one of the hoses of the sensor is either off or plugged, or the orifice is blocked. The signal of the DPFE sensor at idle ranges from .20 to .90 volts DC. The actual voltage will vary depending upon the vehicle. Any voltage reading that is out of that range at idle will usually set a fault code. A fault code will also set if the PCM does not see a sufficient voltage change when EGR operation is commanded. Testing of the DPFE sensor can be done by monitoring its output voltage while applying vacuum to the EGR valve. If you notice an RPM change, or, the engine stalls, and the output voltage does not change, then the sensor is suspect. This assumes that the reference voltage and ground circuits are good. Also, tap on the sensor LIGHTLY to see if the output voltage changes. If the output changes, then the sensor is suspect. The DPFE’s output voltage with "Key On, Engine Off" is between .30 and .60 volts DC. This figure is applicable to the sensor with the aluminum housing. Look for an output voltage that’s about .2 to .3 volts higher for the sensor with the black plastic housing. If you apply vacuum to the EGR valve with the engine at idle, you should notice a change in the sensor’s output voltage, as well as some change in the idle RPM. The common causes of sensor failure are contamination, and excessive exhaust backpressure. Contamination can be caused by exhaust by-products as well other problems such as coolant from a failed gasket. Moisture from condensation can also present problems. One final note about all EEC V OBD II systems: the EGR system will not set any codes as long as the ambient temperature sensor "sees" the temperature below 32°F. Under these conditions, it is likely that if condensation has occurred, it will freeze and create some type of problem..."
K....

Test, Vacuum Video in a 96 5.0, using a hand-held vacuum pump/gauge

Source: by Tony K (Boat Dude, Big Blue) at http://api.viglink.com/api/click?for...rMotors.net%20

....

for the hand-held vacuum pump/gauge, if you don't have or can't borrow one from pals, ck out parts stores or AZ's LOAN-A-TOOL® PROGRAM
Vacuum Pump, Gauge reads 0 to 30 inches of mercury. All aluminum construction with reverse pistol grip for easy one-handed operation. One 24 inch piece of clear plastic tubing included with pump. OEM27010.. they placed it under Valve Train Repair for some reason..lol


MAF Servicing TSB 96-22-5 by Ford for 94-96 ISSUE: The Mass Air Flow (MAF) sensor is not designed to be removed from its body (die-cast or plastic) for servicing. The sensing elements located inside the by-pass tube can be damaged by poking/probing/touching.
ACTION: Service the MAF sensor as an assembly (refer to Figure 1).
WARNING: DO NOT DISASSEMBLE THE MAF SENSOR.
by Ford via miesk5 .. clean it anyway

*** Over oiled K&N Air filters can cause this ***

MAF Cleaning, in a F 150 Source: by Dan N via http://www.fordf150.net/howto/clean-...low-sensor.php
...

See my partially recovered Bronco web site. Thanks to Mr. Schwim!
Navy & DoD (retired) ... THANKS to ALL WHO SERVE!
Please Participate & VOTE in our Full-Size of the Month (F.O.T.M.) & Full-Size of the Year (F.O.T.Y.) Contests[/B] @ https://www.fullsizebronco.com/forum/27-f-o-t-m-voting/

Last edited by miesk5; 08-16-2018 at 01:57 PM.
miesk5 is online now  
post #6 of 10 (permalink) Old 08-17-2018, 02:29 PM Thread Starter
Registered User
 
Hylander's Avatar
 
Join Date: May 2015
Location: Northern Ca.
Posts: 556
Bronco Info: 1996 XLT, 5.8, 4" RC Lift, Procomp 1069 16x8" Wheels, Toyo MT 285/75R16 Tires
iTrader: (0)
Garage
Thanks for the input.

miesk5:
Most of that is greek to me but I am going over all of it.

As of now I just reset the Codes and installed a new fuel filter, also checked for obvious vacuum leaks.

Failure is not an Option.
Hylander is offline  
post #7 of 10 (permalink) Old 08-30-2018, 11:32 PM Thread Starter
Registered User
 
Hylander's Avatar
 
Join Date: May 2015
Location: Northern Ca.
Posts: 556
Bronco Info: 1996 XLT, 5.8, 4" RC Lift, Procomp 1069 16x8" Wheels, Toyo MT 285/75R16 Tires
iTrader: (0)
Garage
Well,
The code stayed away for a week nut just showed up again tonight

Failure is not an Option.
Hylander is offline  
post #8 of 10 (permalink) Old 08-31-2018, 10:17 AM
Moderator
 
miesk5's Avatar
 
Join Date: Oct 2003
Location: Coronado, CA
Posts: 21,905
Bronco Info: 96 Bronco XL 5.0 E4OD, Man Xfer/Hubs
iTrader: (2)
Garage
Yo Hylander,
It happens unfortunately.

Tell us what tests you have done so far, such as for:
vacuum leaks,
fuel pressure
FPR diaphram
vapor cannister, & hoses to Vapor Management Valve (VMV) & TB.
Improperly seated dip stick.
EGR, Leaking gasket. Stuck open EGR valve. Leaking diaphragm.
Air tube openings from MAF Sensor to throttle body
over-oiled air filter
Etc.
This way we can try to make the other more complicated tests easier to perform.

See my partially recovered Bronco web site. Thanks to Mr. Schwim!
Navy & DoD (retired) ... THANKS to ALL WHO SERVE!
Please Participate & VOTE in our Full-Size of the Month (F.O.T.M.) & Full-Size of the Year (F.O.T.Y.) Contests[/B] @ https://www.fullsizebronco.com/forum/27-f-o-t-m-voting/
miesk5 is online now  
post #9 of 10 (permalink) Old 08-31-2018, 02:37 PM Thread Starter
Registered User
 
Hylander's Avatar
 
Join Date: May 2015
Location: Northern Ca.
Posts: 556
Bronco Info: 1996 XLT, 5.8, 4" RC Lift, Procomp 1069 16x8" Wheels, Toyo MT 285/75R16 Tires
iTrader: (0)
Garage
Here is what I checked so far.
Also cleared codes agains.

Leaking fuel pressure regulator. Pull vacuum hose off, any fuel or aroma, replace FPR

Good

Restricted air inlet from atop radiator support through air filter through throttle body. Check air intake for leaks, obstructions and damage.

Good

Check vapor cannister, hoses to Vapor Management Valve (VMV) & TB.
Improperly seated dip stick


Good

Oil overfill.
Exhaust leaks before or near the HO2S's.


Good

Check MAF for contamination; see below)
*** Over oiled K&N Air filters can cause this ***


Good and factory filter setup

Verify vacuum source to fuel pressure regulator.

Good

Also checked intake bolts.

Failure is not an Option.
Hylander is offline  
post #10 of 10 (permalink) Old 08-31-2018, 03:02 PM
Moderator
 
miesk5's Avatar
 
Join Date: Oct 2003
Location: Coronado, CA
Posts: 21,905
Bronco Info: 96 Bronco XL 5.0 E4OD, Man Xfer/Hubs
iTrader: (2)
Garage
Yo H,
Ok, good!
Next, do vacuum leak test

and EGR vacuum test.

pic in a 96 by Tony K

Exhaust leaks before or near the HO2S's.

Verify integrity of the PCV system. Check vacuum hose & valve itself.

The detailed point tests can be done at an automotive electrical shop. Unless you have the proper scan tool that can read the PID values.

Let us know where you need more info,

See my partially recovered Bronco web site. Thanks to Mr. Schwim!
Navy & DoD (retired) ... THANKS to ALL WHO SERVE!
Please Participate & VOTE in our Full-Size of the Month (F.O.T.M.) & Full-Size of the Year (F.O.T.Y.) Contests[/B] @ https://www.fullsizebronco.com/forum/27-f-o-t-m-voting/
miesk5 is online now  
Sponsored Links
Advertisement
 
Reply

  Ford Bronco Forum > Bronco Discussions > 1980-'96 Bronco Tech

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Ford Bronco Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself. DO NOT USE Gmail.com accounts. If you only have a Gmail.com email please contact the administrator here

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome