Overtightened wastegate
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    1. #1
      Junior Member
      Join Date
      Nov 2019

      Overtightened wastegate

      So ever since I completes my M66 swap I was having boost issues, essentially under any throttle the car was hitting ~5ish lbs of boost.
      (Side note the car was previously tuned on e85 and 25lbs of boost)
      While getting the car retuned on 91 through hilton I was still getting this boost issue. I unplugged the tcv from the wastegate and hit 10lbs before letting off with the potential for it getting higher.
      I replaced the tcv, no change, replaced the bps still no change.
      Rob suggested that the wastegate may be overtightened and it can throw the car into limp mode.

      Today I finally had a chance and loosened it one full turn, immediately I am getting around 7-8lbs of boost now.

      Based on this the wastegate mustve been TIGHT!
      Im trying to understand how this system works since it appears ill need to loosen the wastegate at least 3 more turns although I am waiting to hear back.

      Does the ecu have a lower boost map but the wastegate is still so tight that essentially the ecu thinks its overboosting and therefore send the car into limp mode?

      Sent from my SM-G965U using Tapatalk

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    3. #2
      Junior Member JeremyR's Avatar
      Join Date
      Dec 2016
      Oregon, IL
      Yes your correct it's too tight and you will go into overboost and limp mode, and it is overboosting the map. The k24 in the R should be at 7-7.5 psi base boost with the tcv wire unplugged (per contrast) Maybe go half to 1 more turn to get it below 7.5 max base boost.

      Congrats on the m66 swap! It's a bit of a project.
      2005 S60R | DRag 18" DR34, ET40(838) on 235/ Kenda Vezda UHP kr400 | Delrin | PowerStop | Eibach | Fixed/replaced everything at my shop, just rolled 200k, like new. Original engine, trans, & drivetrain.

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