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Thread: what im i missing? idles high and have to push gas to get it to start.

  1. #1
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    what im i missing? idles high and have to push gas to get it to start.

    have to use the peddle to get it to start and once it starts gas peddle no longer works and it idles way to high?

    this is my first time tunning and this is a first start on a 5.3 gen 3 all alm with a sloppy stage 2 cam swapped in to a 740 volvo

    its dbw the peddle, brain and throttle body all out of same truck.
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    Last edited by IWantATurbo; 05-10-2022 at 01:18 PM.

  2. #2
    Stock throttle body? Recalibrate your tps sensor so its 0% at key on.
    2012 Subaru WRX STI
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    GPI VVT Cam, E85 and Fuel System Upgrades, Nitrous Outlet Plate System, Bolt On's, 3.91 w/L99

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  3. #3
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    Quote Originally Posted by 99CamaroSS View Post
    Stock throttle body? Recalibrate your tps sensor so its 0% at key on.
    this is drive by wire? do i still have to calibrate the tps?

    the peddle, brain and throttle body all out of same truck.
    Last edited by IWantATurbo; 05-10-2022 at 01:18 PM.

  4. #4
    Didn't have time to look through everything but try adding to your base running airflow. I have seen that cause a DBW TB to not zero out if it has too much error. They do have a run for 3 minutes and off for a minute and run for three minutes calibration also.
    2012 Subaru WRX STI
    2013 Camaro SS
    2001 Corvette Z06

    GPI VVT Cam, E85 and Fuel System Upgrades, Nitrous Outlet Plate System, Bolt On's, 3.91 w/L99

    www.tappantuning.com/ REMOTE TUNING LINK

  5. #5
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    my dive by wire works with the car on but not running but does nothing when its running?

  6. #6
    Tuning Addict 5FDP's Avatar
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    Both data log shows the MAP stuck at 85kpa, that's an issue.

    Not sure why you zero'd the P0121 tables in the engine diag tab either.

    I think some of your DBW codes are turned off too.
    Last edited by 5FDP; 05-11-2022 at 12:57 AM.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  7. #7
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    i dont have a map that was deleted in my harness.

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    That doesn't sound right, you are going to need a MAP sensor, do you mean MAF delete? I can't look at your tune right now.

  9. #9
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    yes sorry i have no MAF do have a map

  10. #10
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    Okay that makes more sense, then as 5FDP said you need to solve why it is stuck at 85 kPa, it is a VERY important sensor.

  11. #11
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    so i have 3 map sensors tested all 3 in another car and they work (one came out of that car) but none work in my car. tested teh pin out and it was wrong so i fixed it so first wire has 5 volts middle has ground and 3rd dont know how to test? but it wont start at all now??? im so lost

  12. #12
    Tuning Addict 5FDP's Avatar
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    Are they all OEM ac delco map sensors from say a LS1, 4.8/5.3/6.0 engine made before 2007.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  13. #13
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    2 have the same part# for ls1 and the stock one form the 06 silverado

  14. #14
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    If you jumper 5 volts to the MAP signal return, does the scanner show the MAP value go high? And jumpering ground to MAP signal makes it go low? (yes, the MAP signal has an internal pulldown resistor so it should go low with the sensor unplugged/open circuit, but this is just the basics of how you do a bypass test to check a PCM signal circuit)

    I posted MAP wiring/pinouts in your previous thread.

  15. #15
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    ok in the pic you posted i have to ask a dumb question? is a or b the ground? i know i have c in the right spot.
    https://forum.hptuners.com/showthrea...to-a-volvo-740

    then with the scanner on and the key on i just put a jumper form c to signal and then ground to signal to test if the pcm is working right did i under stand that right?

    thanks again you have been a huge help!

    Quote Originally Posted by blindsquirrel View Post
    If you jumper 5 volts to the MAP signal return, does the scanner show the MAP value go high? And jumpering ground to MAP signal makes it go low? (yes, the MAP signal has an internal pulldown resistor so it should go low with the sensor unplugged/open circuit, but this is just the basics of how you do a bypass test to check a PCM signal circuit)

    I posted MAP wiring/pinouts in your previous thread.

  16. #16
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    'Low reference' means ground. The middle pin is the signal output back to the PCM. If you jumper the 5v reference to the signal wire, the PCM should show whatever max MAP value it can read. Remove the jumper and it should go back to the minimum it can read.

    It would probably not be a bad idea to unplug the PCM, too, and check with an ohmmeter that MAP 'A' goes to PCM C1 54, MAP 'B' goes to C2 32, & MAP 'C' goes to C1 48.

    If you're already in this deep and just now figuring out how wiring diagrams work, I don't envy you.

  17. #17
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    so it does nothing when i jump 5v to the sig wire and does go up to 3.6 when i plug the sensor in. then goes back to 1.5 when i unplug it and does nothing when i jump the ground to sig? so next step is to test the 3 wires to the pcm like you said. but looking to me like the pcm is bad?


    Quote Originally Posted by blindsquirrel View Post
    'Low reference' means ground. The middle pin is the signal output back to the PCM. If you jumper the 5v reference to the signal wire, the PCM should show whatever max MAP value it can read. Remove the jumper and it should go back to the minimum it can read.

    It would probably not be a bad idea to unplug the PCM, too, and check with an ohmmeter that MAP 'A' goes to PCM C1 54, MAP 'B' goes to C2 32, & MAP 'C' goes to C1 48.

    If you're already in this deep and just now figuring out how wiring diagrams work, I don't envy you.
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  18. #18
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    That's... not possible, unless you have the wires identified wrong. Did you check that the 5v wire has 5 volts, and the low ref wire has continuity to ground? The signal wire should have 0 volts with the sensor unplugged, but not a true ground (PCM pulls it low through a resistor).

  19. #19
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    yes 5v tested in the right spot ground tested and in right spot. you can watch my hpl only change ever to it was when i pugged sensor in?

  20. #20
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    ok i checked my pin outs and2 where wrong and now fixed. (again could not have done this with out you!) tested it again in the log started with unplugged then pluged sensor in the unpluged it then jumped 5v to sig wire went way up then jumped ground wire to sig. does this all look normal now? also tested all 3 sensors and they are .1 of each other and right around 12 with car off.

    Quote Originally Posted by blindsquirrel View Post
    That's... not possible, unless you have the wires identified wrong. Did you check that the 5v wire has 5 volts, and the low ref wire has continuity to ground? The signal wire should have 0 volts with the sensor unplugged, but not a true ground (PCM pulls it low through a resistor).
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    Last edited by IWantATurbo; 05-12-2022 at 12:52 PM.