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

 

[SenorNoob]

Sound like you have list in roughly correct order. For sure vacuum leak is top likelihood.

 

[Curious Hound]

I would start with checking for vacuum leaks. Also try to inspect the wiring for the upstream O2 sensor. Make sure it is plugged into the harness good, no broken or shorted wires.

How old are the O2 sensors? They rely on a chemical reaction and, therefore have a finite lifespan that ends when the material is depleted.

 

[masanders]

I would start with checking for vacuum leaks. Also try to inspect the wiring for the upstream O2 sensor. Make sure it is plugged into the harness good, no broken or shorted wires.

How old are the O2 sensors? They rely on a chemical reaction and, therefore have a finite lifespan that ends when the material is depleted.

Eric...good to hear from you brother! I'm definitely going to start spraying to find the leak. I've read about using starting fluid or unlit propane. What would you suggest?

As far as the O2 sensors go, I don't think they've been replaced since I inherited the truck from my father. Even then i can't remember him ever replacing them or having them replaced. Off and on lean conditions have always been a thing with this truck.

 

[Curious Hound]

I would probably use brake cleaner or startung fluid. Use the little red tube so you have a more specific idea of where a leak might be. If you just fog the engine bay and the rpm changes, all you van say is "yup. There's a leak somewhere."

I'm doing alright. It has been a strange and busy year for me. Hope you're ok.