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Past 30psi boost?

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  • Past 30psi boost?

    Hey all!

    I installed a defi boost gauge a little while back and I noticed in phase 2 at WOT the needle runs past 30psi and just pegs out....I thought to myself maybe the ECU is still relearning after the battery reset, but about 800 miles later it still does it.

    When this high boost ordeal happens my car goes into a stuttering fit of rage and jerks violently as it cycles between releasing and building more boost. I’m wondering if the ECU is activating some sort of failsafe or it’s just too much pressure to spark well (I have Okadas and NGK at 0.24)

    My next thought is maybe this could be a bad boost sensor of some sort? Thus causing it to think there’s not enough boost while the turbo gives it all it’s got...

    My third thought: can this little turbo even make that much boost?? Could it be the gauge itself and an unrelated problem...

    All ideas and guesses are welcome!

  • #2
    You should not be getting 30psi on Phase 2. The first question I have that comes to mind is about the wastegate actuator. Has it been adjusted or modified in any way? Until this is figured out, run it in non sport mode, or flash Phase 1 or something with lower boost onto the car. 30psi is not normal.



    • #3
      It has a turbosmart wastegate on it.. I set it up per the instructional video, but I think I should just undo it and re-do it to make sure everything is correct.... If this doesn’t work I will try the stock version too, just to see if there is any difference

      Thanks for the tip Greg! I thought it seemed unusual. I’ll report back after I retry it and give it some break-in time

      Just to add this car NEVER goes into vacuum (V4.1 and SuperSprint if it matters) It still does full needle sweeps throughout the range at startup. Is this normal?

      Thanks in advance!


      • #4
        At idle with warmed up engine I pull 20”+- vacuum which I think is normal.


        • #5
          30 psi is absolutely not normal with a Turbosmart installed. Either the preload is way off, or there is something else going on.

          At what point did this boost issue occur? Was anything installed just prior?


          • #6
            Now that I think about it this high boost/stutter issue was occurring before I even installed the turbosmart wastegate because I installed it suspecting that maybe the stock unit was the culprit...

            Prior to flashing to phase 2 I didn’t notice any problem/stutter, probably because less boost was requested and also I didn’t have the defi gauge on yet

            Just thinking out loud - could the wastegate solenoid be a problem area?


            • #7
              It's possible. Either the solenoid and/or the lines to and from. Something is preventing the wastegate actuator from being able to effectively do it's job, which is governing boost. Start by inspecting all the hard plastic lines and rubber elbows for cracks and splits since that costs you nothing. Also inspect the plastic hose barb fittings on the solenoid. I've seen those cracked as well.


              • #8
                What boost gauge are you using? it not showing vacuum would lead me to think possible bad boost gauge/sender.
                13' Abarth


                • #9
                  That was also one of my concerns too, It’s a defi boost gauge (plugged into charge pipe). And it does seem unusual that there is no vacuum shown.. however the boost rises and falls similar to what the factory gauge did

                  maybe the fact that it’s connected to the charge pipe is the problem? I may have to try it on the throttle body for you know, science or something


                  • #10
                    Isn’t there a spot on the intake manifold where it could be plugged into that would give a more accurate reading?
                    2015 Fiat 500 Abarth (Red Rosso, automatic)
                    Alfa 4C Coil Packs
                    ATM FMIC
                    EuroCompusion Euro+Drive Tune (FT695 / Phase 1)
                    EuroCompulsion v4.1 Intake
                    EuroCompulsion/HPSI Silicone Vacuum Line Kit
                    Forge Motorsports Recirculating Blow Off Valve
                    Sila Concepts Thermal Blanket
                    Turbosmart Wastegate Actuator


                    • #11
                      I may have to give that a go, I currently have my methanol hobbs switch plugged into that port, lots of ideas to test out this weekend!

                      I appreciate everyone’s input!!


                      • #12
                        You can't just verify using an OBD app?


                        • #13
                          The charge pipe is not a good source for a boost gauge.
                          2017 FIAT 124 Spider Lusso | EC Euro+Drive Phase 2 | EC V4 intake | EC intercooler | Full GWR exhaust with SportCat | Forge wastegate actuator | GFB DV+ | PTP Lava turbo blanket | Speedhut boost and IAT gauges | Cravenspeed gauge vent pods


                          • #14
                            UPDATES: Okay, sooooo I plugged the boost gauge into the intake manifold port and it shows vacuum now!!

                            Yay! One issue down!

                            The downside is I can still peg out past 30psi in phase zero.... but it’s still in the relearning period from the battery pull, so maybe it’ll even itself out???

                            I also swapped in a new wastegate solenoid to see if that could be a source of issue, but no change. All lines to and from wastegate and solenoid appear to be in good condition (EC Hoses)

                            Next steps include disconnecting the wastegate actuator and reseating it

                            My OBD reads a MAP of around 6psi at idle so this thing might need a cleaning or replacement possibly?


                            • #15
                              You should never see 30 psi with phase 0, fresh reset or not. Something is definitely wrong.