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TPS Adjustment and Voltage Ranges for SR Swaps

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  • TPS Adjustment and Voltage Ranges for SR Swaps

    Don't ask me why, but for the first time since putting the new Throttle body on the car, I actually decided to take a peak at WOT values for the TPS.

    First and foremost, the car runs fantastic, no issues. Just wanted to play with the new laptop, and hook up NissanDataScan on it.

    Now obviously every Nissan has a range in regard to the TPS. I've looked at a few different FSM's, and generally it says WOT should be between 3.5-4.7, or older ones say Approximately 4.0 v

    Closed some say between .15-.85, others .3 to .7

    With that considered, the ECU also has a TPS closed/open feature, which lets to the computer know the car is idling.

    On my s14, I've got a closed value of .20 and a WOT of 3.85 I would assume that this technically means that my range is right where it should be, however it is .15 off of '4v'. The older Nissan FSM's want 4.0, the newer ones say 3.5-4.0 is ok. However if I adjust the TPS so that WOT shows 4.00 volts, the low end raises to .35...which is still in the range, however the ECU now no longer recognizes that the car is idling, bumps the timing up, and idle RPM is raised as well.


    With all things considered, should I just leave it be...or is something else a miss. I guess in the grand scheme of things I want to make sure that I'm actually going true WOT via ECU, or should I ensure it goes to 4.0v at WOT and disregard the ECU knowing the car is idling. I could be over thinking this, but was curious about it.
    'Slicks on a car show me you care - broken axles show me you're trying'
    [I]Nitrous Rental Cars - Turbo Festivas - Vehicular Lunacy[/I]
    [SIZE="3"][B][url]www.sloppymechanics.com[/url][/B][/SIZE]

  • #2
    Leave it like it was. There is nothing special going on with the ECU knowing it is at WOT AFAIK (lots of cars have different maps, but the S13/S14 don't). It does use the TPS for some idle stuff, decel fuel cut, and TPSdot enrichment of course.


    I think mine was about 0.25V closed, just over 4V WOT going from memory.
    '18 Chevrolet Volt - Electric fun hatch for DD duty!


    DefSport Koni Sleeve and Spring Perch Buy!!!
    http://www.nissanroadracing.com/showthread.php?t=5902

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    • #3
      BTW - less lame TPS questions, more GTX dyno! NAOOOOWWW!!!!
      '18 Chevrolet Volt - Electric fun hatch for DD duty!


      DefSport Koni Sleeve and Spring Perch Buy!!!
      http://www.nissanroadracing.com/showthread.php?t=5902

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      • #4
        Originally posted by Def View Post
        BTW - less lame TPS questions, more GTX dyno! NAOOOOWWW!!!!
        The sheets/files from our dyno day are gone. Still trying to work out how to get back on the old dyno to really see.

        I've also been considering dumping the wastegate to atmosphere, while using a little muffler for the dump tube....I honestly never realized that recirculating the wastegate would have hurt power like I've been researching.
        'Slicks on a car show me you care - broken axles show me you're trying'
        [I]Nitrous Rental Cars - Turbo Festivas - Vehicular Lunacy[/I]
        [SIZE="3"][B][url]www.sloppymechanics.com[/url][/B][/SIZE]

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        • #5
          Originally posted by Def View Post
          Leave it like it was. There is nothing special going on with the ECU knowing it is at WOT AFAIK (lots of cars have different maps, but the S13/S14 don't). It does use the TPS for some idle stuff, decel fuel cut, and TPSdot enrichment of course.


          I think mine was about 0.25V closed, just over 4V WOT going from memory.
          That's what I was assuming as well, was just curious as to if it made much difference as far as the TPS value in regard to actual peak power. I guess it was one of those things where my curosity cased worry
          'Slicks on a car show me you care - broken axles show me you're trying'
          [I]Nitrous Rental Cars - Turbo Festivas - Vehicular Lunacy[/I]
          [SIZE="3"][B][url]www.sloppymechanics.com[/url][/B][/SIZE]

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          • #6
            The hot ticket for wg dumps seems to be 1.75" glasspacks. That's what I was planning to do with mine.
            '18 Chevrolet Volt - Electric fun hatch for DD duty!


            DefSport Koni Sleeve and Spring Perch Buy!!!
            http://www.nissanroadracing.com/showthread.php?t=5902

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            • #7
              Originally posted by Def View Post
              The hot ticket for wg dumps seems to be 1.75" glasspacks. That's what I was planning to do with mine.
              I considered that, but check this out:
              http://www.summitracing.com/parts/SU...2005/?rtype=10


              That would work, and be easier to fit where I have it all setup.

              Edit: The only reason those things even came into my mind, is that the Porsche guys utilize them at LimeRock (well, super trapps but a different type) to conform to the Db requirements.

              Don't get me wrong, I have it all setup to merge back in nicely as it is (no sharp angle, following the stream...but I'd be curious to the actual gains. Some guys claim 15-25 hp at the 400 whp level, which would be great.
              'Slicks on a car show me you care - broken axles show me you're trying'
              [I]Nitrous Rental Cars - Turbo Festivas - Vehicular Lunacy[/I]
              [SIZE="3"][B][url]www.sloppymechanics.com[/url][/B][/SIZE]

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              • #8
                Would merging it further down the exhaust stream (closer to catback) has less of an effect on power? Granted it adds more tubing/weight.

                cheers
                -Evan

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                • #9
                  Originally posted by CodyAce View Post
                  I considered that, but check this out:
                  http://www.summitracing.com/parts/SU...2005/?rtype=10


                  That would work, and be easier to fit where I have it all setup.

                  Edit: The only reason those things even came into my mind, is that the Porsche guys utilize them at LimeRock (well, super trapps but a different type) to conform to the Db requirements.

                  Don't get me wrong, I have it all setup to merge back in nicely as it is (no sharp angle, following the stream...but I'd be curious to the actual gains. Some guys claim 15-25 hp at the 400 whp level, which would be great.
                  I don't think you'll gain that much, but you might gain a few HP. You're probably operating at above a 2.0 pressure ratio at that much power, so for every .1 psi you add to the exhaust you're going to get .2 psi at the turbine inlet. So you don't need to chop off a ton of backpressure to bring down your turbine inlet pressure.
                  '18 Chevrolet Volt - Electric fun hatch for DD duty!


                  DefSport Koni Sleeve and Spring Perch Buy!!!
                  http://www.nissanroadracing.com/showthread.php?t=5902

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                  • #10
                    Cody,

                    You must tell the ECU the TB is closed for it to register as the "new" idle voltage,

                    IIRC,

                    diconnect TPS,

                    Start car,

                    rev a couple times to 2-3

                    let settle to idle,

                    turn off car,

                    plug TPS in,

                    Start car,

                    Confirm Datascan registers TPS IDLE at closed throttle,

                    however as Def stated it makes no difference, as long as your voltage doesn't max before WOT occurs you are fine.
                    I am SKULLWORKS

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