2.5L ('98-'01) P1131 diagnostic help...LOTS of data!

[masanders]

Evening folks!

I'm starting down the path to trying to figure out what is wrong with my '00 2.5L Ranger. I searched the forum and read all of the posts that have to do with this particular MIL code and have found a lot of useful ideas and symptoms that match what my truck is doing. I even consulted the Ranger tech section and will be using the O2 sensor article as a guide to help track this issue down. So far, research on The Ranger Station, BlueDriver OBD2 reader, and other forums point to the following possible issues:

• Vacuum lines
• Intake manifold gaskets
• Mass air flow sensor
• PCV valve or cracked PCV valve hose/tube
• Clogged/Dirty throttle body valve
• Upstream O2 sensor
• Air leak between MAF and Throttle Body
• Oil dipstick unseated
• Leaking EGR gasket
• Stuck EGR valve
  • Diaphragm or EGR Vacuum Regulator
• Exhaust leaks before upstream O2 sensor
• PCM - Engine computer
• Fuse issues

I've pulled all the data I can from the BlueDriver reader and have listed it below. I'm sorry it's so long. I'm just trying to be as thorough as i can be. If you know much about sensor data, could you take a look? I'm planning on cleaning the MAF, checking the PCV and the hose, and cleaning the throttle body valve. I will also be running electrical reference tests on the O2 sensor and MAF. Unfortunately most of the to-do list relies on the next paycheck to come in, so it'll have to wait.


OBD2 Sensor Readings
BlueDriver with current firmware
2000 Ford Ranger 2.5L 4x2 @ 242,945 miles
Code: P1131 Lack of Upstream Heated Oxygen Sensor Switch – Sensor Indicates Lean – Bank No. 1.
Did have P0171 Code: System Too Lean Bank 1. Code has gone away.

• Mass Air Flow Sensor
  • Before Throttle Blip
    • 0.5 - 0.6 lb/min (4.01 - 4.38 g/s)
  • After Throttle Blip
    • 0.4 - 0.5 lb/min (2.95 - 3.83 g/s)
  • Key On Engine Off
    • .1 lb/m (.55 g/s)
• Fuel System Status
  • Before Throttle Blip
    • Open Loop due to detected system fault
  • After Throttle Blip
    • Closed Loop
  • Key On Engine Off
    • Open
• Bank One Sensor One Voltage
  • Before Throttle Blip
    • 0.000v - 0.050v
  • After Throttle Blip
    • 0.025v - 0.780v
  • Key On Engine Off
    • 0.005v - 0.010v
• Short Term Fuel Trim
  • Before Throttle Blip
    • Started at 3.1% - 8.6%.
    • Changed to -17.2% - 42.2%
    • Held steady at 0.0% for about 10+ minutes until throttle blip
  • After Throttle Blip
    • -92.2 (very briefly) - 9.4%
  • Key On Engine Off
    • 12.5% - 13.3%
• Long Term Fuel Trim
  • Before Throttle Blip
    • 14.8% - 16.4%
  • After Throttle Blip
    • 14.1% - 15.6%
  • Key On Engine Off
    • 0.0%
• Other Readings
  • Absolute Throttle Position
    • Before Throttle Blip
      • 16.5%
    • After Throttle Blip
      • 16.5%
  • Calculated Engine Load
    • Before Throttle Blip
      • 28.6%
    • After Throttle Blip
      • 28.6%
  • Intake Air Temperature
    • Before Throttle Blip
      • 112°F
    • After Throttle Blip
      • 134°F
  • Timing Advance Cyl 1
    • Before Throttle Blip
      • 8.0° - 9.5°
    • After Throttle Blip
      • 7.5° - 12.5°
    • Engine Idle Speed
      • Before Throttle Blip
        • Between 948 - 970 RPM
      • After Throttle Blip
        • Between 948 - 970 RPM

Freeze Frame Report @ 242,800 miles

• (02) DTC that caused freeze frame data - P1131 Lack of Upstream Heated Oxygen Sensor Switch – Sensor Indicates Lean – Bank No. 1
• (03) Fuel System Status Closed loop - using all oxygen sensor(s) as feedback for fuel control
• (04) Calculated Engine Load Value - 48.2 %
• (05) Engine Coolant Temperature - 170.6 °F
• (06) Short Term Fuel Trim Bank 1 - 42.2 %
• (07) Long Term Fuel Trim Bank 1 - 15.6 %
• (0C) Engine RPM - 2200 rpm
• (0D) Vehicle Speed - 46 MPH

Mode6 Data attached - too much to type up. I don't understand it anyway.



If you made it this far, thank you! I'm hoping you guys can help me think of things i haven't thought of yet.

Mark