Bringing TBI and Multi Port Fuel Injection to a New Level.     EFI Conversions and Tuning! Seattle to Portland! E-mail Tuning Consultant!
Page 3 of 4 FirstFirst 1234 LastLast
Results 31 to 45 of 46

Thread: O2 ?

  1. #31
    Fuel Injected!
    Join Date
    Oct 2013
    Posts
    859
    Quote Originally Posted by C2500 View Post
    Dave do you have a pin out pic like above for a 6395 eco that’s in my truck? Or where can I find one..
    Thanks
    It should be $0E.

    http://www.gearhead-efi.com/Fuel-Inj...Information-OE

  2. #32
    Fuel Injected!
    Join Date
    Oct 2012
    Location
    Boynton Beach Florida
    Age
    55
    Posts
    46
    Yes the Tan wire circuit 413 is a separate wire that is GROUNDED at G160 along with Circuit 450 Sensor return ECM ground
    In the ECM the pin that 413 is attached too is almost always grounded at the ECM buss as well.

    The lambda amplifier is an Operational amplifier and or comparator the main difference between the differential amplifier and the Operational amplifier is the ground reference of the OP amp.

    Operational Amplifer
    Comparator
    Differential Amplifier

    Prior models use the same circuit as the National instruments matlab adapter for O2 sensors.
    O2_Sensor_UM_RevD.pdf
    As you can see the manual for the engineering and design tool used for the creation of the ECM shows how the one lead of the sensor is tied to ground through the EGO- buss. This is the same setup used up to 1993 on the sheet metal cased ECMs.
    The only reason I say 1993 is thats when I retired from GM.

    Here is the Chip or similar used most commonly from 1995 on (1991 on some models)
    LM9044

    On page one under Typical Application you see the diagram of the chip internals it is a differential amplifier followed by ground referenced OP amp.
    This is the stye used from 1995 on when the chips where first made available.


    The whole thread was about how to wire the different sensors to a system with a one wire sensor it is simple you ground the 4th wire.
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

  3. #33
    Fuel Injected!
    Join Date
    Oct 2012
    Location
    Boynton Beach Florida
    Age
    55
    Posts
    46
    Quote Originally Posted by lionelhutz View Post
    Cool thanks I did not have these
    Added to library of old stuff.

    Does anyone have the factory diagnostic wiring diagrams with the connector and splice locations for the C1500 Suburban?
    Last edited by daveosx; 01-09-2018 at 01:07 PM.
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

  4. #34
    Fuel Injected!
    Join Date
    Oct 2013
    Posts
    859
    Quote Originally Posted by daveosx View Post
    Yes the Tan wire circuit 413 is a separate wire that is GROUNDED at G160 along with Circuit 450 Sensor return ECM ground
    In the ECM the pin that 413 is attached too is almost always grounded at the ECM buss as well.
    Why is a separate wire needed if it's just grounded to the other ground pins?


    Quote Originally Posted by daveosx View Post
    As you can see the manual for the engineering and design tool used for the creation of the ECM...
    Where can I see the original design documents used for the '7747 ECM?


    Quote Originally Posted by daveosx View Post
    Here is the Chip or similar used most commonly from 1995 on (1991 on some models)
    LM9044

    On page one under Typical Application you see the diagram of the chip internals it is a differential amplifier followed by ground referenced OP amp.
    This is the stye used from 1995 on when the chips where first made available.
    That chip still has the same pin connections as the chip for the O2 in the '7747. The '7747 chip has different pin numbers on the package, because it is DIP, not PLCC.

    What are you meaning with the internal description? A differential amplifier allows both input pins to float from the ground and it will still output the difference.The stage after is internal in the IC so it doesn't need to be differential. Right from the datasheet the IC will work with up to -3V on the O2 input pins.

    Did that style of chip become available in 91 or 95? You're contradicting yourself.

  5. #35
    Fuel Injected!
    Join Date
    Oct 2012
    Location
    Boynton Beach Florida
    Age
    55
    Posts
    46
    Quote Originally Posted by lionelhutz View Post
    Why is a separate wire needed if it's just grounded to the other ground pins?




    Where can I see the original design documents used for the '7747 ECM?




    That chip still has the same pin connections as the chip for the O2 in the '7747. The '7747 chip has different pin numbers on the package, because it is DIP, not PLCC.

    What are you meaning with the internal description? A differential amplifier allows both input pins to float from the ground and it will still output the difference.The stage after is internal in the IC so it doesn't need to be differential. Right from the datasheet the IC will work with up to -3V on the O2 input pins.

    Did that style of chip become available in 91 or 95? You're contradicting yourself.
    The tan wire was a design intent to use a differential amp on the earlier sensors but the costs associated with O2 sensors that far back and the need to economize on wiring and parts kind of won out. On the early 1970s and 1980s controllers noise was a huge issue. Lambda feed back was kind of a novel way to accomplish feedback. But putting shielded cable in a harness was too costly. Later top end cars did get shielded cable when needed but the lower end cars had different solutions. Hense the single wire O2 sensors from Bosch.

    I have no idea where to get design notes. maybe one of the other engineers still has some stuff left over.
    The guy who did most of the digital dash for vettes has shared the original dash schematics.
    I have a copy if you would like them.

    If it has a lambda amplifier in a different package (DIP vs PLCC) then thats the reason but I do not believe that the O2 amp is a lambda differential amp on the sheet metal ECMs.
    On the cast aluminum ECMs there is a differential amplifier.
    On early models the amp is discrete on later it is integrated.

    The early ones 91 to 95 are discrete the Lambda chip came out in 1995 and was used from 1996 model year on.

    No contradiction

    When thinking about this and understanding how a differential sensor and amplifier works the two input lines are held equally between ground and VCC+.
    The output of an old style Operational amp has the ability to change from about .7V above ground level to about .7 v below VCC+ So in typical use they where run with -15V VSS and +15V VCC. In a car you have start sag voltage of 9V and full charge voltage of 14.8V no -Vss available. SO you use the Operational Amps that function on single supply and confine the voltage to a working VCC usually 5V but I have seen Nissan and BMW controllers at 6 and 9 V VCC.

    O2 sensor voltage varies from .35V to .9V a differential amplifier built from a single supply operational amp will have an output proportional to the difference between the two wires of the sensor. An operational amplifier with a ground reference will have an output proportional to the difference between the ground and the input signal.
    A lambda amplifier uses a differential amp feed into a Operational amp providing output proportional to the difference between the ground and the differential amp signal.

    So if you use a four wire sensor on a system with a grounded TAN 413 wire just ground two of the O2 sensors wires run the heater wire to 12V in run and the other wire to 412 purple wire.

    The reason you would not just ground one input of a differential amp is that there is a bias circuit used to float the two inputs equal between ground and VCC this will become a current path if one input is grounded. (Dead Battery)

    if you wanted to make a differential lambda circuit you can use an LM358 single supply OP amp 4 20K resistors 2 1k 2 10k and have a four wire O2 sensor amplifier that will give you 3.5V to 9V output when used with 12V VCC and ground on VSS.


    Screen Shot 2018-01-09 at 9.40.26 PM.jpg
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

  6. #36
    Fuel Injected!
    Join Date
    Oct 2013
    Posts
    859
    I would bet money the PCM in this thread uses a lambda IC and can be hooked to a 4-wire sensor as I suggested.

    The negative side of the sensor element in a 4-wire sensor is still tied to the case of the O2 sensor. I just measured this with a meter and the negative sensor pin IS grounded to the case. Look at the typical application diagram of the TI datasheet and it shows this ground connection at the sensor end too. So, no need for any other ground on the sensor circuit. No need to worry about noise from an ungrounded sensor either.

    You posted "Here is the Chip or similar used most commonly from 1995 on (1991 on some models)" and then posted that lambda chips came out in 95. Definitely contradicting.

    You posted "as you can see" about some kind of engineering and design tool manual used to create the ECU, so I was assuming you missed a link to some documents because none of the links you posted had anything to do with designing the old ECU's.


    Quote Originally Posted by daveosx View Post
    The reason you would not just ground one input of a differential amp is that there is a bias circuit used to float the two inputs equal between ground and VCC this will become a current path if one input is grounded.

    Sure, if that was the circuit. But those lambda IC's do not have such a bias circuit. The datasheet even recommends grounding the sensor negative lead at the O2 sensor. There are biasing current sources on the pins, but they are not doing as you suggest. They are to provide a default voltage output if the wiring to the sensor opens.

    I have seen the schematics of the '7746 ECU, which is basically the same boards as the '7747. Just for you, I'll look it up and post the links.

    Input schematic, O2 sensor is bottom right

    https://pcmhacking.net/ludis/1228746sheet3.gif

    The lambda IC.

    https://pcmhacking.net/ludis/c3pinouts.html#16007757

    It's the same IC circuit but in DIP case. The DIP version was probably long discontinued before TI bought National so TI did not bother with posting datasheets of it. Yes, TI bought National maybe 8 or 10 years ago.

    The 1995 date on the TI datasheet is likely the date the PLCC version of that lambda IC was released.

    If the '7747 era ECU's had the lambda IC then this later model PCM definitely has it.

  7. #37
    Fuel Injected!
    Join Date
    Oct 2012
    Location
    Boynton Beach Florida
    Age
    55
    Posts
    46
    If an earlier model 1991 - 1995 uses a differential amplifier for the input of the O2 than it is a similar circuit to the lambda chip that came out in 1995 and was used from 1995 on. This is not a contradiction.
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

  8. #38
    Fuel Injected!
    Join Date
    Oct 2012
    Location
    Boynton Beach Florida
    Age
    55
    Posts
    46
    Looking at your references I see that yes it is a similar chip.
    What GM cars shipped in 1991-1995 with a four wire and sheet metal ECU cases
    My knowledge was that only the aluminum cast cases had differential amps.

    And as I stated grounding one side off a differential amplifier input would create a path to ground.
    http://www.ti.com/lit/ds/symlink/lm9044.pdf
    Page 7 block diagram shows
    two current sources one 65nA the other 380nA at the -Vin on this specific chip when -Vin is grounded that would be a current path to ground.
    Most likely the source is switched not battery.
    Last edited by daveosx; 01-10-2018 at 01:31 PM.
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

  9. #39
    Fuel Injected!
    Join Date
    Oct 2012
    Location
    Boynton Beach Florida
    Age
    55
    Posts
    46
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

  10. #40
    Fuel Injected!
    Join Date
    Oct 2012
    Location
    Boynton Beach Florida
    Age
    55
    Posts
    46
    Not seeing a four wire with any internal grounds.
    0900c1528008be6f.jpg

    What O2 sensor are you using?
    It might be a three or four wire replacement maybe IDK.
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

  11. #41
    Fuel Injected!
    Join Date
    Oct 2012
    Location
    Boynton Beach Florida
    Age
    55
    Posts
    46
    Anyway the whole point to my posting was that if the 413 lead is grounded then you can just ground the other sensor wire.

    I think the whole reason for going to the 4 wire sensor with isolated sensing element was to eliminate the galvanic and induced voltages that are present between ECM ground and the bung on the exhaust pipe. In a modern engine you have many different metals and induced currents and resistances.
    .7 volt is a very small voltage that is easily lost in the other noise.

    Using a 2 wire shielded cable grounded at the ECM would have been the best solution.
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

  12. #42
    Fuel Injected!
    Join Date
    Oct 2013
    Posts
    859
    The sensing element in the O2 sensor is NOT isolated!!!

    http://www.ti.com/lit/ds/symlink/lm9044.pdf

    Page 1 clearly shows grounding the negative side at the sensor. The sensors have the connection. I have tested it. Do I need to take a picture of the ohm meter reading to prove the connection exists in a sensor?

    Of course grounding the negative lead creates a path to ground. The lead is connected to ground for crying out loud.

    But that should not be confused with claiming it screws up the chip, because the chip is designed with the expectation that the negative lead will be grounded.

    The use of a 1, 3 or 4 wire O2 is rather irrelevant to the IC used inside the PCM. How many cast case PCM's with the lambda IC didn't use a 4-wire O2?

    If you are going to use a 4-wire O2 then why leave the wiring with 2 separate connections to the engine or transmission or exhaust? Just avoid any possible connection issues and connect the O2 sensor wires right to the ECU/PCM and be done with it.

    If you are going to leave connections to the engine block then you might as well stick with a 3-wire sensor.
    Last edited by lionelhutz; 01-10-2018 at 02:00 PM.

  13. #43
    Fuel Injected!
    Join Date
    Oct 2012
    Location
    Boynton Beach Florida
    Age
    55
    Posts
    46
    Quote Originally Posted by lionelhutz View Post
    Sure, if that was the circuit. But those lambda IC's do not have such a bias circuit. The datasheet even recommends grounding the sensor negative lead at the O2 sensor. There are biasing current sources on the pins, but they are not doing as you suggest. They are to provide a default voltage output if the wiring to the sensor opens.
    Actually some Lambda chips have another op amp that monitors for open.

    I think that it is possible that the internals of a OP amp in discreet components and the tri angle symbol are hiding the current path I am speaking of.

    On page 10 of the LM9044 data sheet there is a simplified internal diagram.
    The V-in terminal is biased through a 10Kohm resistor through three transistors to VCC the ground side bias path is 10K through collector to base (weird) through 7.6K and 3.4k adjustable.

    An open circuit would provide Vref through 400 200 Vout
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

  14. #44
    Fuel Injected!
    Join Date
    Oct 2012
    Location
    Boynton Beach Florida
    Age
    55
    Posts
    46
    Quote Originally Posted by lionelhutz View Post
    The sensing element in the O2 sensor is NOT isolated!!!

    http://www.ti.com/lit/ds/symlink/lm9044.pdf

    Page 1 clearly shows grounding the negative side at the sensor. The sensors have the connection. I have tested it. Do I need to take a picture of the ohm meter reading to prove the connection exists in a sensor?

    Of course grounding the negative lead creates a path to ground. The lead is connected to ground for crying out loud.

    But that should not be confused with claiming it screws up the chip, because the chip is designed with the expectation that the negative lead will be grounded.

    The use of a 1, 3 or 4 wire O2 is rather irrelevant to the IC used inside the PCM. How many cast case PCM's with the lambda IC didn't use a 4-wire O2?

    If you are going to use a 4-wire O2 then why leave the wiring with 2 separate connections to the engine or transmission or exhaust? Just avoid any possible connection issues and connect the O2 sensor wires right to the ECU/PCM and be done with it.

    If you are going to leave connections to the engine block then you might as well stick with a 3-wire sensor.
    Great discussion by the way making me pull out old books and links to chips.

    Yes I see that the application note shows a ground in the sensor.

    I disagree about the grounding is intended by the chip design not likely.

    Thats interesting that your four wire could be used in a three wire setup could be a manufacturer cost savings thing.

    Here is the diagram for three and four wire narrowband sensors.
    O2 sensor.jpg

    and another authoritative source on wideband sensors
    https://emsd.weebly.com/wide-band-o2-sensor.html


    I do not see the indication of a ground internal on the four wire of either.

    As far as why wire to the block instead of the ECM ?
    The cylinder head of either bank is typically less than 2 feet from the O2 bung and the ECM is typically on the inside of the car.
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

  15. #45
    Fuel Injected!
    Join Date
    Oct 2012
    Location
    Boynton Beach Florida
    Age
    55
    Posts
    46
    To answer why the notes for electronic fuel injection controllers are not easily referenced.
    Take a look at the D-Jetronic prior to O2 sensor inclusion.
    d-jetronic_ecu_schematic1_touchedup.jpgd-jetronic_ecu_schamatic2_touchedup.jpgd-jetronic_ecu_schematic3_touchedup.jpg
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •