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S13 SR20 - Strange power cut out when going full throttle for too long

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  • S13 SR20 - Strange power cut out when going full throttle for too long

    Hey all, I'm hitting the track in two weeks time so I'm trying to remove the speed limiter fuel cut ****. Strange thing is, isn't the factory speed limiter at 180km/h(112mph) like every other Japanese domestic market vehicle?

    Cause I've tried this but never reached 180. It keeps cutting out at around 160km/h(99mph). And its an abrupt cut out, the power is completely cut out for a good 3-4 seconds and the speed drops below 140km/h(86mph) before I have any sort of power again. It is not a spluttering or a misfire, it feels like a deliberate electronic cut out determined by the ECU.

    Another thing related to this is that when I do full throttle for a while on the spot (ie burnout) staying in 1st gear the power will cut out after maybe 30 seconds at wide open throttle. Doing the same thing as described above where I cannot apply power again until after 3-4 seconds.

    Also, when I run the car on a hoist. I can wind the speed out way above 180km/h(112mph) I just put it in 5th and accelerate to somethign like 250km/h(155mph) with no cut outs of any sort. So speed cut must not be the issue here?

    I've done a search and found nothing.

    My car is running standard ECU. Walbro GS342 fuel pump, standard 370cc red top injectors, running 10psi on a T28.

    Any pointers?

    Cheers.

  • #2
    Not sure if the SR ECU will cut fuel if you overvolt the MAF, but you will be right around there with 10 psi on a T28.

    Drop the boost some and I bet it goes away.... and get a tune, injectors, and MAF before you smoke your engine.
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    • #3
      Originally posted by Def View Post
      Not sure if the SR ECU will cut fuel if you overvolt the MAF, but you will be right around there with 10 psi on a T28.

      Drop the boost some and I bet it goes away.... and get a tune, injectors, and MAF before you smoke your engine.
      Overvolt the AFM? Could you shed some light on this? If it was going to max out wouldn't it have done so as soon as I reach a certain RPM under load? And not wait 30 seconds until it cuts out at max load (smoking tyres bouncing on rev limiter).

      Surely it can handle 3psi above factory on OEM management.

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      • #4
        Not on a T28 it can't, especially on an S13 SR MAF.
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        DefSport Koni Sleeve and Spring Perch Buy!!!
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        • #5
          I just read this on SR20Tuning.com:

          The Dreaded 'Boost Cut'
          When this maximum voltage output condition happens [in the AFM] the ecu will see it as a big problem and cut the fueling and timing to stop the engine. Known commonly and incorrectly as the 'boost cut', this is what fuel cut defenders aim to override. The condition is called the 'boost cut' because people often discover it when raising the boost. The ecu does not know what boost the car is running however, the addition airflow of the new boost level causing the afm max instead. This means that the cut does not occur at the same boost level on every car. People might say that the 'boost cut' is at 14psi, but this is wrong. The maxing out of the afm will depend on the overall mass of air into the engine, which is obviously decided by a lot more than just the boost pressure a turbo is running.
          However, I am still confused as to why it only max's out the AFM after prolonged W.O.T applications? Theoretically if it was going to max it out wouldn't it achieve this as soon as I hit a certain RPM when accelerating??

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          • #6
            I've never hit it, but the limits in the stock ECU are not equally high across all RPM zones. So it probably takes you a while of running to really hit it, so your setup is borderline on the stock ECU.
            '18 Chevrolet Volt - Electric fun hatch for DD duty!


            DefSport Koni Sleeve and Spring Perch Buy!!!
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            • #7
              Interesting. Cheers for the insight my man.

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              • #8
                I'm running stock ECU,INJ and MAf at their limits. In my opinion you hit the speed limiter.
                Remember, your dash might not be showing the exact speed. Data log it and you will know.

                The boost limiter is bull****, managed to over-boost my T28 daily... and it didn't cut.

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                • #9
                  Originally posted by WorkInProgressK View Post
                  I'm running stock ECU,INJ and MAf at their limits. In my opinion you hit the speed limiter.
                  Remember, your dash might not be showing the exact speed. Data log it and you will know.

                  The boost limiter is bull****, managed to over-boost my T28 daily... and it didn't cut.
                  What sort of turbo and exhaust and how much boost are you running? Was this with factory ECU? Red top or black top?

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                  • #10
                    I have two cars

                    I have hit 210kph(datalogged) multiple times at mosport with a daughterboard(stock tune removed speed limiter on redtop ecu(50F00/62) that canceled the speed limiter. Stock maf, 370 stock injectors and maf. Running 11-12 psi with a GT2871R. 3inch full exhaust.

                    Second car, drifted, wastegate pressure line fell off. Hit 25 psi at 4000rpm= Blown head gasket. Same daughterboard tune. Stock exhaust. GT25R(T28 BB).

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                    • #11
                      I max'd out the stock MAF voltage at 11 psi with a GT2560R and bolt-ons. According to injector duty cycle and judging by dyno graphs and logs I have on the dyno, it was making about 260-265 rwhp towards redline with a FReddy intake manifold - no way stock S13 SR stuff can keep up with that and keep the engine happy.

                      This is the crap that people do that then earns engines the reputation of being "fragile."
                      '18 Chevrolet Volt - Electric fun hatch for DD duty!


                      DefSport Koni Sleeve and Spring Perch Buy!!!
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                      • #12
                        ^^ I have been very methodical in my engine destruction.

                        On a serious note, I need to start saving up for proper injectors. I don't trust my used set of deatschwerks injectors that I bought. The re-drilling seems a little weird and inconsistent with each injector.

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                        • #13
                          So track day was yesterday.

                          I put the boost down to 8psi and I was still experiencing the same thing. It always cut out at around 160km/h when at full throttle.

                          I then tried to apply 3/4 throttle in 3rd and 4th gear and i actually made it to 170km/h.

                          Wierd ****ing ****. Just gonna ditch the factory management all together.

                          Heres a photo for fun

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