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Part Throttle Hesitation/Hiccup

Posted: Fri Apr 24, 2015 6:57 am
by kevinmcc2
I have been experiencing some hesitation/hiccup at part throttle trying to accelerate. Once I hit around 25% throttle I get a jerk of power, WOT is fine and anything below say 20% throttle is fine. It happens in all gears.

Causes I have been told and were as follows but wanted to get some more opinions before throwing money

I have currently

Stage 2 CT supercharger
skun2 header
full race exhaust
hybrid cai
  • Injectors
    Spark Plugs (changed no effect)
    Its normal
    Throttle tip in retard I was told if I set all 6 gears to -100% this will smooth out the sensation.
I attached some datalogs if anyone would like to view and lemme know your thoughts

Just getting a second opinion, this issue is the most annoying thing ever to me!

Any help welcome thanks all!

Re: Part Throttle Hesitation/Hiccup

Posted: Fri Apr 24, 2015 9:56 am
by Spunkster
The datalog looks like it might be the bypass valve closing on the supercharger and it is starting to transition into boost.

Re: Part Throttle Hesitation/Hiccup

Posted: Fri Apr 24, 2015 10:10 am
by kevinmcc2
Would this be something that is fixable or does it look like a bad or sticky bypass valve?

If it is the bypass valve instead of the injectors that would be a lot less I would have to spend. Right now it is so annoying to the point i dont like driving the car around town.

Re: Part Throttle Hesitation/Hiccup

Posted: Fri Apr 24, 2015 10:21 am
by Spunkster
Has this been properly tuned on the dyno?

Re: Part Throttle Hesitation/Hiccup

Posted: Fri Apr 24, 2015 10:31 am
by kevinmcc2
I have a full e-tune from Vit.

Re: Part Throttle Hesitation/Hiccup

Posted: Fri Apr 24, 2015 12:27 pm
by kevinmcc2
Do you think it could be the bypass not opening up smoothly and not delivering boost as linear and smooth?

Re: Part Throttle Hesitation/Hiccup

Posted: Fri Apr 24, 2015 4:56 pm
by Spunkster
Its really hard to say without seeing it in person. Have you discussed this with your tuner?

Re: Part Throttle Hesitation/Hiccup

Posted: Fri Apr 24, 2015 5:14 pm
by kevinmcc2
I actually disconnected the bypass valve and plugged the hose because jon bond performance told me to see if it made a difference and the car felt so much smoother and better.

now i got to find a vacuum gauge and see if the bypass valve is leaking. i really hope it is cause i loved how the car drove with it disconnected lol

Re: Part Throttle Hesitation/Hiccup

Posted: Tue Apr 28, 2015 2:41 pm
by VitViper
There isn't anything "wrong". The logs show pretty clearly the transition from closed loop to open loop as the bypass closes and the motor either starts to see boost or gets close to it, there's your jerk of power. My personal supercharged 8th gen did the same thing, our 9th gen S/C car does it too.