Car jolts from turbo?
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This is a discussion on Car jolts from turbo? within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Is it normal for a car to jolt/shake when the turbo kicks in? My 2003 Wrx does sometimes, but not ...

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    Car jolts from turbo?

    Is it normal for a car to jolt/shake when the turbo kicks in? My 2003 Wrx does sometimes, but not everytime. Right before It kicks in and I pick up speed the car jolts so bad things in my glove box and stuff raddle around. Is this normal? It is my first car with a turbo in it, I'm a newb.

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    There is a big change in the g-force when the turbo kicks in. Sometimes I lose my glasses from it. They tend to fly out from the little cubby under my radio.
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    Okay, my sunglasses actually do that too. So it's normal, that's a relief I was starting to think it was a problem.

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    Before your car goes into-open loop fueling, it needs to meet certain criteria. To test for these criteria, there is a latency period between closed-loop and open-loop fueling. For bugeyes, the latency is longer than the later-generation WRXs. It's tough to illustrate, but when I floor my bugeye, it will attempt to target 14.7:1 AFR for about a half a second before the car enters open-loop fueling with AFRs closer to 11:1. When this transition occurs, the car jolts slightly. This may be what you are experiencing. If you floor the car, let off the throttle, then floor it again, does it still stutter?
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    Quote Originally Posted by zax View Post
    Before your car goes into-open loop fueling, it needs to meet certain criteria. To test for these criteria, there is a latency period between closed-loop and open-loop fueling. For bugeyes, the latency is longer than the later-generation WRXs. It's tough to illustrate, but when I floor my bugeye, it will attempt to target 14.7:1 AFR for about a half a second before the car enters open-loop fueling with AFRs closer to 11:1. When this transition occurs, the car jolts slightly. This may be what you are experiencing. If you floor the car, let off the throttle, then floor it again, does it still stutter?
    I've never tried that before, I'll let you know when I get the chance. Usually once it kicks in and jolts it doesn't happen again untill I slow down or come to a stop and go again.

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    zax
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    Quote Originally Posted by Weedity View Post
    I've never tried that before, I'll let you know when I get the chance. Usually once it kicks in and jolts it doesn't happen again untill I slow down or come to a stop and go again.
    Yep. That sounds like what I'd expect. It hasn't entered closed-loop until you have stabilized your RPM again for a short period of time.
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    Quote Originally Posted by zax View Post
    Yep. That sounds like what I'd expect. It hasn't entered closed-loop until you have stabilized your RPM again for a short period of time.
    I'm new to all this, so is it bad if it isn't stabilized when the turbo kicks? How can I tell it's stabilized enough?

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