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Thread: O2 sensors...UGHHHHHHH

  1. #11
    Join Date
    Jul 2014
    Location
    Houston
    Posts
    30
    Yes sir, I'm clear on the pinks. I will double check the fuses to be sure nothing is blown. I've also read the O2 sensors should be warm to the touch with the ignition on engine off. Are you aware if this is accurate or not. Again, thanks for your input.

  2. #12
    Join Date
    Mar 2013
    Location
    Long Beach California
    Posts
    637
    this is what i found on lt1swap for your year pcm

    DRIVER
    1 BLK/WHT 451 PCM Ground
    28 TAN/WHT 1669 HO2S Signal Low B1S2 (w/Case Ground O2 Sensors)
    28 TAN 413 HO2S Signal Low B1S2 (w/Isolated Ground O2 Sensors)
    29 TAN/WHT 1653 HO2S Signal Low B1S1 (w/Case Ground O2 Sensors)
    29 TAN 413 HO2S Signal Low B1S1 (w/Isolated Ground O2 Sensors)
    68 PPL/WHT 1668 HO2S Signal High Bank 1 Sensor 2
    69 PPL/WHT 1665 HO2S Signal High Bank 1 Sensor 1


    PASSENGER
    1 BLK/WHT 451 PCM Ground
    26 TAN 1667 HO2S Signal Low B2S1 (w/Case Ground O2 Sensors)
    26 TAN 413 HO2S Signal Low B2S1 (w/Isolated Ground O2 Sensors)
    25 TAN 1671 HO2S Signal Low B2S2 (w/Case Ground O2 Sensors)
    25 TAN 413 HO2S Signal Low B2S2 (w/Isolated Ground O2 Sensors)
    65 PPL 1670 HO2S Signal High Bank 2 Sensor 2
    66 PPL 1666 HO2S Signal High Bank 2 Sensor 1

    what i dont get is why there is second option for either high or low for the first sensor in each bank which would make a "5th" wire. i assume it makes a differnce depending on if you have isolated ground or not. but i have not dealt with this so im not positive. i have a feeling this is where your problem lies. also you mentioned that you have a pink wire (which is not on the list i provided) on pin 3 which states that pin is for injector control....
    3 PNK/BLK 1746 Injector 3 Control

    as stated, we think its a wiring issue. try and wire it up per lt1 swap and see if that fixes it and if so then you need to contact the company that made your harness and tell them they screwed up.
    Last edited by kewljay223; 05-03-2016 at 11:03 PM.
    Like Tumbler in "Gone in 60" I'll drive anything with wheels or without

    My 95 ECSB LQ9 build thread - http://www.ls1truck.com/forums/lsx-t...to-95-obs.html
    CALI LEGAL ENGINE SWAP!
    Stock 03 LQ9, DBW, 95' 4l80e w/ Transgo shift kit, 2010 50# GM injectors, 2800 Circle D stall, Spectre CAI, Upgraded trans cooler, Home-made E-fans/shroud, Dual EP-381 fuel pumps w/Home-made hotwire kit
    NEXT ON LIST: Dual Battery setup, CAM/Valvetrain upgrade, Build my own rear mount turbo, TRU-TRAC, HIT THE STRIP!!!

  3. #13
    Join Date
    Mar 2013
    Location
    Long Beach California
    Posts
    637
    Quote Originally Posted by L8RH8R View Post
    Yes sir, I'm clear on the pinks. I will double check the fuses to be sure nothing is blown. I've also read the O2 sensors should be warm to the touch with the ignition on engine off. Are you aware if this is accurate or not. Again, thanks for your input.
    thats true because when you turn the ignition on, the heaters are activated thus them getting warm
    Like Tumbler in "Gone in 60" I'll drive anything with wheels or without

    My 95 ECSB LQ9 build thread - http://www.ls1truck.com/forums/lsx-t...to-95-obs.html
    CALI LEGAL ENGINE SWAP!
    Stock 03 LQ9, DBW, 95' 4l80e w/ Transgo shift kit, 2010 50# GM injectors, 2800 Circle D stall, Spectre CAI, Upgraded trans cooler, Home-made E-fans/shroud, Dual EP-381 fuel pumps w/Home-made hotwire kit
    NEXT ON LIST: Dual Battery setup, CAM/Valvetrain upgrade, Build my own rear mount turbo, TRU-TRAC, HIT THE STRIP!!!

  4. #14
    Join Date
    Mar 2013
    Location
    Long Beach California
    Posts
    637
    BTW that was a pain in the ass so you better figure this out. haha
    Like Tumbler in "Gone in 60" I'll drive anything with wheels or without

    My 95 ECSB LQ9 build thread - http://www.ls1truck.com/forums/lsx-t...to-95-obs.html
    CALI LEGAL ENGINE SWAP!
    Stock 03 LQ9, DBW, 95' 4l80e w/ Transgo shift kit, 2010 50# GM injectors, 2800 Circle D stall, Spectre CAI, Upgraded trans cooler, Home-made E-fans/shroud, Dual EP-381 fuel pumps w/Home-made hotwire kit
    NEXT ON LIST: Dual Battery setup, CAM/Valvetrain upgrade, Build my own rear mount turbo, TRU-TRAC, HIT THE STRIP!!!

  5. #15
    Join Date
    Jul 2014
    Location
    Houston
    Posts
    30
    LOL! Gonna work on it some more this weekend and post what I find if anything. I do appreciate the input. Anything helps.

  6. #16
    Join Date
    Aug 2014
    Posts
    18
    I am having the same or similar problem. I have a 2004 4.8L and The CEL is on for P0135 and P0155. Always both at the same time. I too have 12V power to sensor and the ground is good. Sensors show a resistance of 6 ohms which is suppose to be good. I don't know about the MV. It will stay off for days at a time, but always comes back on. Along with a P0101 MAF code , and that has been replaced. I will be following your thread!

  7. #17
    Join Date
    Jul 2014
    Location
    Houston
    Posts
    30
    I am still facing this problem. We are now considering maybe the fuel pressure is not high enough. Currently, it is about 42 psi, which is measured by an autometer gauge mounted on the fuel rail. When the regulator is unplugged, it raises to about 50. I am running a 225 gph walbro in tank pump. The lines were upgraded to braided stainless and connected to the factory hard lines. Another thought was the exhaust was not getting hot enough to activate the sensors. The sensors are mounted in the collector on shorty headers. Using a thermal scanner, the cylinders are getting up to approx. 230 degrees. It is my understanding the O2's need to see about 600 degrees. I am still stumped.

  8. #18
    Join Date
    Jul 2010
    Location
    Douglasville Ga
    Posts
    224
    Where are you located? If I had the truck, I could straighten it out for easier than trying to do it remotely. That being said, here's a little info on how Zirconia narrow band O2s work. GM sends a bias voltage of approximately 445 mv. This is done as a way for the PCM to verify signal circuit integrity during the O2 "warm up stage". Once the O2 sensor begins to operate, it creates its own voltage in approximately a 100-900mv range and this voltage swing overcomes the 445mv bias. Since the scan tool displays bias voltage all the time, I would begin by back probing the signal circuit (at the 02 connector) and ground the circuit. If the scan tool now displays 0V, the signal circuit is good and pinned correctly.

    Then you can move on to the sensor ground (low reference). With the back probe still in place on the signal circuit, now also back probe the low reference circuit and jumper it to the signal circuit. If the scan tool displays 0v again, the the low reference circuit is good too. You've already verified switched hot and ground on the heater circuit right?

    I am with Jay. I suspect your harness has the wrong low reference configuration. I would try splicing into the low ref circuits and add the "5th" wire and recheck.

    If the O2s are staying at 445mv, you can ignore fuel pressure etc. 445 means either an open circuit on the signal wire, failed (open) O2 sensor, poor sensor ground (low ref) or sensor now warming up. The heater in the O2 is strong enough in most cases to light off the O2 without any heat from the exhaust so don't worry about your exhaust temps.

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