|07-26-2001, 12:31 PM||#1|
*** Banned ***
Join Date: Nov 2000
Location: Connecticut, USAVehicle:
02 WRX Sedan
2002 Impreza Front Air/Fuel Sensor
Their seems to be a difference between the front air/fuel sensor used in the 2002 WRX (DOHC) and the unit used in the 2002 Impreza non-turbos (SOHC). The non-turbos have two extra wires.
Ignoring heater, shielding/grounding and sensor power, here's the service manual description of the two sensor wires for the WRX:
Front Oxygen (A/F) sensor signal (+) Idle Volts = 2.8 - 3.2
Front Oxygen (A/F) sensor signal (-) Idle Volts = 2.4 - 2.7
Here's the description of the 4 sensor wires for the non-turbo:
Front Oxygen (A/F) sensor signal 1 Idle Volts = 2.8 - 3.2
Front Oxygen (A/F) sensor signal 2 Idle Volts = 2.4 - 2.7
Front Oxygen (A/F) sensor signal 3 Idle Volts = 0.2 - 4.9
Front Oxygen (A/F) sensor signal 4 Idle Volts = 0.2 - 4.9
The WRX ECU can issue a diagnostic trouble code P1134 - FRONT OXYGEN (A/F) SENSOR MICRO-COMPUTER PROBLEM, whose remedy is to replace the ECU. The non-turbo ECU has no similar DTC.
The Subaru Select Monitor can display, for the WRX, front sensor current (mA) and resistance (Ohms), but cannot display this info with the non-turbos.
I suspect that the sensors are the same but the non-turbo sensor pigtail/connector contains circuitry which performs the function, more or less, of the "sensor micro-computer" embedded within the WRX's ECU. I suspect that the WRX's front sensor current and resistance are intermediate results, enroute to the final result of a 0-5V signal representing the A/F ratio. I suspect that the circuitry in the non-turbo sensor's pigtail/connector is supplying this same 0-5V signal directly to the non-turbo ECU.
It seems, therefore, a possibility that a non-turbo A/F sensor could be swapped into the turbo (or at least its outboard circuitry) and then its extra 0-5V signal could be used to drive an Air/Fuel Ratio meter that would likely be very accurate.
* Registered users of the site do not see these ads.
|Thread||Thread Starter||Forum||Replies||Last Post|
|FS NY:02-05 wrx front air fuel sensor o2||FastfreddyRs||Engine/Power/Exhaust||4||06-01-2010 09:01 AM|
|Front Oxygen sensor AKA air/fuel sensor swap out||Peaty||Tribeca Forum||0||02-20-2010 04:36 PM|
|FS: 2005 STi Bank 1 Air/Fuel Sensor O2 Sensor||srREXed||Engine/Power/Exhaust||0||08-14-2008 07:34 PM|
|Moving front air/fuel sensor further downstream||bryan_johnson||Subaru Conversions||3||05-10-2005 05:39 PM|
|WRX Front Air/Fuel Sensor Info||Jon [in CT]||Factory 2.0L Turbo Powertrain||2||08-14-2001 02:25 PM|