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Thread: 94 Supra 2JZGTE - Map Ecu1

  1. #1

    Default 94 Supra 2JZGTE - Map Ecu1

    Hi everyone,

    When installing a mapecu1 could someone please clarify if i am supposed to T-Splice into for example the IGF wire (rpm signal) or the VTA1 (throttle position sensor), etc?

    Im not sure if and what signals are "shared" by the oem ecu and the mapecu or what are inputs vs outputs?
    I can see that the VG (Mass airflow) signal to the oem ecu is completely replaced by the green wire from the mapecu i just dont know about the rest.

    Thank you for your help!

    wiring diagram > http://www.mapecu.com/wp-content/upl...US-MAP-ECU.pdf
    Attached Images Attached Images
    Last edited by red946; 30th-December-2015 at 02:00 PM.

  2. #2

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    The rest of the wires are just a splice in and are "shared". Do not cut any wires besides the VG

  3. #3

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    Thanks,
    I have another question do you know if its important that the oem ecu and mapecu share the same ground?
    I have an aem wideband installed and I read on this forum that its really important that the wideband and the mapecu share the same ground preferably a thick wire.

    Im not sure which is more important, i'd like to keep the stock ecu grounded the way it is...

  4. #4

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    Quote Originally Posted by red946 View Post
    Thanks,
    I have another question do you know if its important that the oem ecu and mapecu share the same ground?
    I have an aem wideband installed and I read on this forum that its really important that the wideband and the mapecu share the same ground preferably a thick wire.

    Im not sure which is more important, i'd like to keep the stock ecu grounded the way it is...
    Which AEM wideband do you have?

    I would recommend grounding the map ecu to the OEM ecu and then check and see if the AFR readings from the gauge match MAP CAL. If they do don't worry about any other grounds. The reasoning for grounding the wideband to the map ecu is so that the AFR readings on the gauge will match what the map ECU is reading.

  5. #5

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    I have an AEM 30-4100 it uses the bosch LSU4.2
    i looked at the wiring diagram and i think im just going to run a good ground wire from the Wideband/Mapecu to the intake manifold where all the sensors and stock ecu get grounded ultimately.
    i took some screenshots, its labeled ED
    ecu ground.JPGsupra grounds.JPG

  6. #6

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    Quote Originally Posted by red946 View Post
    I have an AEM 30-4100 it uses the bosch LSU4.2
    i looked at the wiring diagram and i think im just going to run a good ground wire from the Wideband/Mapecu to the intake manifold where all the sensors and stock ecu get grounded ultimately.
    i took some screenshots, its labeled ED
    ecu ground.JPGsupra grounds.JPG
    That should work but may be a bit of overkill. The OEM ecu grounds to the brown wires you see bolted right under the intake manifold
    img_0133.jpg

  7. #7

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    Thanks for providing some great support Ask92. Just to add to that, it is critical that the MAPECU, OEM ECU and wideband are all at the same ground potential otherwise the OEM ECU will see changing MAF voltage from the MAPECU and the MAPECU will see changing AFR from the wideband. It is also important to understand the difference between the grounds. We connect the MAPECU to the OEM ECU sensor ground wires so make sure it is the same as the old MAF sensor. The wideband has 2 grounds, one for the electronics and one for the O2 sensor heater. The O2 sensor heater is very high current so you must use a seperate ground wire to the one for the electronics otherwise you get variations in the ground when the O2 heater is on. This will manifest itself in different AFR reads on the MAPECU.
    MAP-ECU Support

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