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Thread: Magnuson Silverado throttle oscillation help

  1. #21
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    Looks like something is working. Almost too easy. I had to hunt extra variables down on my E67 to get that working. Looks like the torque models are needing some adjustment though. Trans gets a little frisky with the throttle...

  2. #22
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    Quote Originally Posted by Alvin View Post
    I take it that you installed a SCIAP sensor?

    That's good to know it fixed it for you.
    yes sciap sensor is installed .. i tried to replicate the throttle oscilation and i was not able to replicate, looks like this was the true solution for that problem, i know tune still needs work but that throttle oscilation was anoying. thanks for the knownledge and your time guys.

  3. #23
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    Quote Originally Posted by smokeshow View Post
    Looks like something is working. Almost too easy. I had to hunt extra variables down on my E67 to get that working. Looks like the torque models are needing some adjustment though. Trans gets a little frisky with the throttle...
    yes looks like it was that easy, i apreciate the help,time and the shared knownledge.

  4. #24
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    Quote Originally Posted by castorjames View Post
    yes sciap sensor is installed .. i tried to replicate the throttle oscilation and i was not able to replicate, looks like this was the true solution for that problem, i know tune still needs work but that throttle oscilation was anoying. thanks for the knownledge and your time guys.
    Which pins on the ECM are you using for SCIAP and MAP?

  5. #25
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    Quote Originally Posted by pisces_0 View Post
    Which pins on the ECM are you using for SCIAP and MAP?
    E92 X1 Pin 4 is the signal for the throttle inlet pressure on the NA cars or if you have a factory SC can they use that pin for the supercharger inlet and use X2 pin 45 for the throttle inlet. So you could probably wire it up to work as the OE engineers know you need this set up to control the throttle as smokeshow pointed out.

    exactly like that (map stays in the same pins)

  6. #26
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    Quote Originally Posted by castorjames View Post
    E92 X1 Pin 4 is the signal for the throttle inlet pressure on the NA cars or if you have a factory SC can they use that pin for the supercharger inlet and use X2 pin 45 for the throttle inlet. So you could probably wire it up to work as the OE engineers know you need this set up to control the throttle as smokeshow pointed out.

    exactly like that (map stays in the same pins)
    I'd like confirmation before I open up the ECM harness.

    On an L83 ECM, does the added SCIAP sensor signal wire replace Pin 4, X1 plug (where the TIAP sensor signal currently resides) or insert into blank space Pin 45, X2 plug?

    Both the L83 and LT4 utilize a TIAP sensor signal, so I'm assuming TIAP needs to stay put in Pin 4, X1, and SCIAP goes into Pin 45, X2.

    Also, where do you supply 5V power and ground? Are there unused pins on the ECM for these? I really don't want to hack into existing 5V and ground to tap off of.

  7. #27
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    Just re-read previous posts, and I think I got it.

    TIAP moves from Pin 4, X1 plug into Pin 45, X2 plug. SCIAP goes into Pin 4, X1 plug.

    Correct?

    5V power and ground for the SCIAP?

  8. #28
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    Quote Originally Posted by pisces_0 View Post
    Just re-read previous posts, and I think I got it.

    TIAP moves from Pin 4, X1 plug into Pin 45, X2 plug. SCIAP goes into Pin 4, X1 plug.

    Correct?

    5V power and ground for the SCIAP?
    Just buttoned this up over the weekend. This is on a 2016 Suburban, L83 5.3L. SCIAP sensor is in and functioning as expected.

    I can echo castorjames results. The addition of an SCIAP sensor and polishing the Driver Demand table has 110% solved my throttle oscillation and spike issues. Accelerator pedal and throttle position track each other spot-on in virtually all scenarios now.

    This does require opening up the ECM connectors and removing/installing pins. Tedious, detailed work but fairly straightforward.

    ECM Modifications
    X1 Pin 4 (TIAP Sensor Signal) -> move to X2 Pin 45
    X1 Pin 5 (TIAP Sensor 5V) -> move to X2 Pin 64
    X1 Pin 4 -> add Pin 1 on SCIAP Sensor Signal
    X1 Pin 5 -> add Pin 3 on SCIAP Sensor 5V
    X1 Pin 20 -> add Pin 2 on SCIAP Sensor Gnd

    This mirrors the LT4 ECM pinout. Probably didn't have to move the 5V power wires, but my OCD required me to move them over.

    Update Pressure Sensor Type to SCIAP-TIAP in the tune.

    Vapor Worx remote MAP sensor mount:
    https://www.vaporworx.com/shop/produ...nting-bracket/

    Used the stock L83 MAP sensor, GM 12644228.

    Repoll for supported parameters in VCM Scanner, and you can add the Supercharger Inlet Pressure PID.

  9. #29
    What pressure/vac source are you feeding into the SCIAP?

  10. #30
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    Quote Originally Posted by str8dum1 View Post
    What pressure/vac source are you feeding into the SCIAP?
    I'm running a Whipple on a 5.3L, so not totally apples to apples as this thread is about a Magnusson.

    My SCIAP sensor is plumbed into one of the ports on the supercharger housing just past the throttle body.

    Picture below is from Whipple's site, and I circled the port I added a quick-connect fitting to. Routed a short length of vacuum hose down to the remote-mount MAP sensor housing noted above.

    337_LT1_800.jpg

  11. #31
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    Can anyone confirm the L87 / E90 ecm pin configuration?

  12. #32
    Where did you buy the extra pins needed to add the sensor?

    Quote Originally Posted by pisces_0 View Post
    Just buttoned this up over the weekend. This is on a 2016 Suburban, L83 5.3L. SCIAP sensor is in and functioning as expected.

    I can echo castorjames results. The addition of an SCIAP sensor and polishing the Driver Demand table has 110% solved my throttle oscillation and spike issues. Accelerator pedal and throttle position track each other spot-on in virtually all scenarios now.

    This does require opening up the ECM connectors and removing/installing pins. Tedious, detailed work but fairly straightforward.

    ECM Modifications
    X1 Pin 4 (TIAP Sensor Signal) -> move to X2 Pin 45
    X1 Pin 5 (TIAP Sensor 5V) -> move to X2 Pin 64
    X1 Pin 4 -> add Pin 1 on SCIAP Sensor Signal
    X1 Pin 5 -> add Pin 3 on SCIAP Sensor 5V
    X1 Pin 20 -> add Pin 2 on SCIAP Sensor Gnd

    This mirrors the LT4 ECM pinout. Probably didn't have to move the 5V power wires, but my OCD required me to move them over.

    Update Pressure Sensor Type to SCIAP-TIAP in the tune.

    Vapor Worx remote MAP sensor mount:
    https://www.vaporworx.com/shop/produ...nting-bracket/

    Used the stock L83 MAP sensor, GM 12644228.

    Repoll for supported parameters in VCM Scanner, and you can add the Supercharger Inlet Pressure PID.

  13. #33
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    What's the part number for the sensor you used?

  14. #34
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    Quote Originally Posted by str8dum1 View Post
    Where did you buy the extra pins needed to add the sensor?
    I hit up a local junkyard and clipped off an ECM connector from a wrecked '16 Impala. De-pinned the connector and had 6"-8" of wire to solder to.

  15. #35
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    Quote Originally Posted by Smurf4R View Post
    What's the part number for the sensor you used?
    I used the stock MAP sensor from my Suburban.

    GM 12644226

  16. #36
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    Wired in and turned on sensor stuck at 14.5psi engine off or running doesnt move. Have 4v to sensor reading thru scanner. tried different sensors same thing. unplugged i have volatge and then it shows 14.5 on vacuum side or sometimes 1. Im logging the pressure vacuum and volatge. Any help appreciated.

  17. #37
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    I'm having a similar issue.

    I wired in a LS1 style map sensor just cause the housing can accept a vacuum line without buying a CNC'ed adapter.

    I ASSume its recognizes a issue with the SCIAP and just matches the pressure/vacuum to Baro pressure.

    While scanning I've unplugged the MAF to test to make sure the baro is reporting the right sensor. It is..

    I've unplugged the new SCIAP to makes sure SCIAP voltage goes to zero. It does

    I've made sure there is vacuum on the map sensor. I can see the voltage change while running and revving but the SCIAP reports the inlet vacuum to be the same as baro.

    In this log at one point I disconnect the vacuum line going to the sensor. You can see the SCIAP vaccum nor pressure changes at all but the voltage goes up to (4.6 i believe)

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  18. #38
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    Still working on this.. Used a stock SCIAP sensor. Same results. I can see voltage moving but SCIAP inlet vacuum always reads the same at the moment 97kpa
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  19. #39
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    Quote Originally Posted by Alvin View Post
    Still working on this.. Used a stock SCIAP sensor. Same results. I can see voltage moving but SCIAP inlet vacuum always reads the same at the moment 97kpa
    To be honest I expected the results from this to be mixed - I was surprised a couple guys above were able to enable it so easily. It took be a bit more digging on the E67 to get it working, including some parameters that HPT had not defined.

    You'll probably want to enable P012B and associated diagnostics to start - not passing a sensor diagnostic is a good reason for the software to ignore its input. Indicating that a SC is fitted would be the next thing I'd try. Unfortunately there's no cut and dry way to do this - all depends on what code was and was not common between different powertrain trim levels and how diligent the calibrators were with carryover calibrations that had no effect on the vehicle.

  20. #40
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    Quote Originally Posted by smokeshow View Post
    To be honest I expected the results from this to be mixed - I was surprised a couple guys above were able to enable it so easily. It took be a bit more digging on the E67 to get it working, including some parameters that HPT had not defined.

    You'll probably want to enable P012B and associated diagnostics to start - not passing a sensor diagnostic is a good reason for the software to ignore its input. Indicating that a SC is fitted would be the next thing I'd try. Unfortunately there's no cut and dry way to do this - all depends on what code was and was not common between different powertrain trim levels and how diligent the calibrators were with carryover calibrations that had no effect on the vehicle.
    So I tried to use a LS1 style map sensor since it would be easier to hook up a vacuum line without buying a sensor block ETC. That did not seem to work. No matter how I set the ambient air pressure sensors (94.43 x 10.33) for that one.. the inlet air pressure read different from BARO.

    With the LS3 style bolt in map sensor scaler x constant (128.2 x -.31) the inlet pressure sensor at least read what the baro did.

    But the results were very very obvious. It went from just about dangerous driveablity to just about perfect. Completely fixed the part throttle surge PD blowers seem to have as the bypass starts to close. It's just the scanner never read right.. Inlet pressure was always fixed at 97kPa.
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