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Thread: 12200411 - A Few General Questions

  1. #1
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    12200411 - A Few General Questions

    Greetings- New member here looking to pick some brains
    Looking to install a FIRST TPI system into my 69' Corvette utilizing the 1220411 PCM.
    It's running a 409 SBC, 5-speed with A/C- Strictly a play toy, not a 1/4 miler..
    As I sift though the volumes of information on the subject, I do have several questions that I have not been able to find the answers. Perhaps someone can chime in?

    Distributor:
    Has anyone attempted to graft the Vortec style distributor reluctor wheel and CMP onto a points style GM distributor?
    I plan on running sequential injection with a single coil and distributor and I want to keep the original mechanical tach drive intact. I'd love to see if anyone has done this.

    Knock sensors:
    It seems the later 'Flat Response' style are more flexible than the 'Resonant' style (and I don't like the idea of losing a block drain to install it)- Is there any difference other than the connector between the 21024981 (Vortec) and 12623730 (LS) Knock Sensor? Which would be best for my application?

    VSS:
    I'm running a 5-Speed manual (SS 700). Do I need a VSS to run the 12200411? What does the VSS get me?
    I don't have cruise control, will have cable driven throttle and I am running stock analog instruments so unless there is a performance or reliability advantage, do I need it?

    Clutch Switch:
    Not sure if this is used in conjunction with the VSS or if it works alone? Is there an advantage to using it? Should I?

    Oil Pressure Sensor:
    Again, is this something I need? I have a mechanical oil pressure gauge and I really don't need the PCM to alert me (by shutting down) if my oil pressure is gone. Is there any other advantage for having it other than an engine safety net?

    MAF sensor:
    This may be a dumb question but I can't seem to find an answer. Is size a factor? I'm assuming the MAF needs to be at least the same diameter as the throttle body but does it matter if it's bigger (IE wanting to use the 5-wire, 85mm MAF sensor with a 71mm throttle body)?

    I hope I haven't scared folks away with my first post but these are the bulk of the questions I currently have.
    Any experience, insight or wisdom would be most appreciated.
    Also, I'd love to hear from anyone that has installed EFI (any kind) into a C3.
    Thank you for your time!
    Elm

  2. #2
    Super Moderator dave w's Avatar
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    Quote Originally Posted by ezobens View Post
    Distributor:
    Has anyone attempted to graft the Vortec style distributor reluctor wheel and CMP onto a points style GM distributor?
    I plan on running sequential injection with a single coil and distributor and I want to keep the original mechanical tach drive intact. I'd love to see if anyone has done this.
    With some advanced CAD work and CNC machining, anything is po$$ible. See Pics below for a Chrysler distributor custom made for use with an '0411 PCM.

    Quote Originally Posted by ezobens View Post
    Knock sensors:
    It seems the later 'Flat Response' style are more flexible than the 'Resonant' style (and I don't like the idea of losing a block drain to install it)- Is there any difference other than the connector between the 21024981 (Vortec) and 12623730 (LS) Knock Sensor? Which would be best for my application?
    I would simply remove the knock sensor when I needed to drain the block. I would use the knock sensor from a 2002 Express Van 5.7 liter.

    Quote Originally Posted by ezobens View Post
    VSS:
    I'm running a 5-Speed manual (SS 700). Do I need a VSS to run the 12200411? What does the VSS get me?
    I don't have cruise control, will have cable driven throttle and I am running stock analog instruments so unless there is a performance or reliability advantage, do I need it?
    The VSS can be eliminated in the PCM programming.


    Quote Originally Posted by ezobens View Post
    Clutch Switch:
    Not sure if this is used in conjunction with the VSS or if it works alone? Is there an advantage to using it? Should I?
    The clutch switch can be eliminated in the PCM programming.

    Quote Originally Posted by ezobens View Post
    Oil Pressure Sensor:
    Again, is this something I need? I have a mechanical oil pressure gauge and I really don't need the PCM to alert me (by shutting down) if my oil pressure is gone. Is there any other advantage for having it other than an engine safety net?
    The oil pressure sensor can be eliminated in the PCM programming.

    Quote Originally Posted by ezobens View Post
    MAF sensor:
    This may be a dumb question but I can't seem to find an answer. Is size a factor? I'm assuming the MAF needs to be at least the same diameter as the throttle body but does it matter if it's bigger (IE wanting to use the 5-wire, 85mm MAF sensor with a 71mm throttle body)?
    The 5 wire MAF can be used, as long as the PCM programming is set up for the 85mm MAF settings.

    I would recommend installing a Normally Closed Brake Switch for the '0411 PCM.

    dave w
    Attached Images Attached Images

  3. #3
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    Dave,
    Thanks again for jumping in!

    I like the custom reluctor- I saw an outfit on-line called BET Performance that has something similar but the distributor is pricey if all I want this the reluctor.
    Perhaps I can inquire if they'd sell just that one part?
    Who made the reluctor in your pictures above?

    Ok,
    So VSS,Oil PSI and Clutch Switch don't appear mandatory or advantageous for my application.
    What function does the Brake Switch serve?

    Any reason why you would use the Resonant vs Flat Response Knock Sensor?
    I'm concerned that my engine might false trigger the Resonant style sensor more often than not (mechanical flat tappet cam and roller rocker noise).
    Thoughts?

    Thanks again!
    Elm

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    While a vss can be eliminated, its much better to run it. You can add a dakota digital vss that goes between your trans and speedo cable. Not using loses you resolution on your timing table and makes idle a little more interesting. The $40 it takes to add it is worth it in my opinion.

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    I'm curious (and sorry of this is a dumb question) but how does a 'Speed' sensor help at idle since the car is stationary at idle?
    Just trying to understand.
    Thanks!
    Elm

  6. #6
    EFI GearHead ! EagleMark's Avatar
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    Quote Originally Posted by mecanicman View Post
    While a vss can be eliminated, its much better to run it. You can add a dakota digital vss that goes between your trans and speedo cable. Not using loses you resolution on your timing table and makes idle a little more interesting. The $40 it takes to add it is worth it in my opinion.
    X2!

    I've done several differant EFI systems without VSS and some were a lot of tuning work! Then add VSS and they all ran better, even if you don't need accurate speed, just the ECM/PCM knowing the vehicle is moving or not makes Idle so much better. Amongst other things!

    Also done a lot of differant motors with TBI injection and made a small cap EFI distributor for every one. Jeep, Ford, Chrysler, etc...

    http://www.gearhead-efi.com/Fuel-Inj...BI-Conversions!

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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    Its transitions between moving and idle, the computer has different strategies. If you never have a vss, the computer bases all "decisions" on you sitting still. It can be compensated for by putting more air into running airflow table then you normally would.

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    Quote Originally Posted by ezobens View Post
    Any reason why you would use the Resonant vs Flat Response Knock Sensor?
    I'm concerned that my engine might false trigger the Resonant style sensor more often than not (mechanical flat tappet cam and roller rocker noise).
    With the 0411 PCM the L31 Vortec engines (Express / Savana) were equipped with Resonant style knock sensors, just like the LSx engines were. There are no OEM defined tables / settings for Flat Response style knocks sensors with these engines using a PCM (0411).

    If you conduct an internet search regarding operating an LS2 engine with a PCM, you will read for hours about all of the impasses to attempting to correctly integrate Flat Response knock sensors and a PCM (0411).

    Some have tried (and failed) to use the knock sensor settings from a 4.3L V6 using Flat Response knock sensors and a PCM (0411).

    Their are couple of companies who offer a wiring harness and PCM that will supposedly achieve this - they don't work. These are typically sold as LS2 conversion kits. Anyone using one of these setups has no knock protection.

    Most people who have swapped in a 24x CKP LS2 have mounted the Resonant style knock sensors.

  9. #9
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    Quote Originally Posted by EagleMark View Post
    X2!

    I've done several differant EFI systems without VSS and some were a lot of tuning work! Then add VSS and they all ran better, even if you don't need accurate speed, just the ECM/PCM knowing the vehicle is moving or not makes Idle so much better. Amongst other things!

    Also done a lot of differant motors with TBI injection and made a small cap EFI distributor for every one. Jeep, Ford, Chrysler, etc...

    http://www.gearhead-efi.com/Fuel-Inj...BI-Conversions!
    I've seen this post and it's very ingenious- Unfortunately, I don't think I can utilize the 2 piece shaft arrangement in my application due to the mechanical tach drive and the cam plate assembly required to attach the points style rotor. I think my best bet will be to alter the cam plate to allow me to attach the reluctor securely.
    Luckily, I have a lot of spare OEM points distributors laying around that I can butcher (err- "Engineer") and try to make something that works.
    The biggest machining operation would be to the notch the main body so I could attach the OEM CMP sensor without having to notch distributor caps.
    Thanks for the ideas!
    Elm

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    Quote Originally Posted by Buzz View Post
    With the 0411 PCM the L31 Vortec engines (Express / Savana) were equipped with Resonant style knock sensors, just like the LSx engines were. There are no OEM defined tables / settings for Flat Response style knocks sensors with these engines using a PCM (0411).

    If you conduct an internet search regarding operating an LS2 engine with a PCM, you will read for hours about all of the impasses to attempting to correctly integrate Flat Response knock sensors and a PCM (0411).

    Some have tried (and failed) to use the knock sensor settings from a 4.3L V6 using Flat Response knock sensors and a PCM (0411).

    Their are couple of companies who offer a wiring harness and PCM that will supposedly achieve this - they don't work. These are typically sold as LS2 conversion kits. Anyone using one of these setups has no knock protection.

    Most people who have swapped in a 24x CKP LS2 have mounted the Resonant style knock sensors.
    OK-
    I was following the path of since the the 4.3L Vortec used the Flat Response Sensors with the 12200411 PCM, why couldn't I just overwrite the 5.7L Knock code with the 4.3L? Seems from the outside that this wouldn't be hard to do but then I have ZERO experience playing with any code within these controllers.
    Bummer, on paper it sounds like this would be a fairly easy switch but it sounds like not so much.
    Thanks!
    Elm

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    Quote Originally Posted by mecanicman View Post
    Its transitions between moving and idle, the computer has different strategies. If you never have a vss, the computer bases all "decisions" on you sitting still. It can be compensated for by putting more air into running airflow table then you normally would.
    Sounds like the VSS may be something I need to consider-
    Does the clutch switch play any role with this idle strategy as well?
    Thanks!
    Elm

  12. #12
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    Quote Originally Posted by ezobens View Post
    Sounds like the VSS may be something I need to consider-
    Does the clutch switch play any role with this idle strategy as well?
    Thanks!
    Elm
    Yes, but it is easiar to tune around in my opinion.

  13. #13
    EFI GearHead ! EagleMark's Avatar
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    What role does clutch signal play? Isn't it needed for Case Relearn? Or was that Parking Brake on manuals?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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    If the brake switch is solely for Case Re-Learn, I'd rather just wire a toggle switch vs wiring in the Emergency Brake-
    Or are their TWO brake signals (one for the foot and one for the emergency brake)?

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    Quote Originally Posted by EagleMark View Post
    What role does clutch signal play? Isn't it needed for Case Relearn? Or was that Parking Brake on manuals?
    The biggest place you would notice it is when coasting down, high vacum situation where the tires are driving the engine. Stepping on the clutch pedal changes the airflow requirements, pcm compensates. Base running airflow and throttle cracker can cover this.
    Last edited by mecanicman; 12-05-2013 at 10:24 PM.

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