Author Topic: bouncy acceleration with low throttle  (Read 752 times)

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Offline Gargoyle

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bouncy acceleration with low throttle
« on: February 23, 2018, 02:50:53 PM »
so a few months ago my 2010 wrx started this weird jerky acceleration. basically in normal driving i accelerate slowly from a light or whatever i have constant steady pressure on the pedal but the car accelerates like im pressing harder, then releasing, then harder, then releasing, like it's reading a sine wave instead of my foot pressure. i don't get a cel. the car is soul crushingly stock with 150k km. i did take it to a shop and they did the easy checks, no intake leaks post maf, cleaned the maf, checked a spark plug and everything came back normal/no problems. it doesn't seem to do it at any other time, if im in boost it doesn't, only low throttle. it does it whether warm or cold, and in every gear, it seems like it might always be the same throttle position but it might just seem that way

the rpms also drop more than they should when i come to a stop, instead of just dropping to idle (~700) they tend to go down to 500 or so, it hasn't actually died yet, not sure if the two things are related

any ideas? my next step would probably be taking it to the dealership but they generally charge a lot of money, but i will if i have to

Offline diamondedge

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Re: bouncy acceleration with low throttle
« Reply #1 on: February 23, 2018, 04:05:03 PM »
I wonder if your TPS sensor is going bad, or if the DBW is going bad itself. I figured you would have a CEL so I'm stumped aside from those two things.

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Offline Gargoyle

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Re: bouncy acceleration with low throttle
« Reply #2 on: February 23, 2018, 04:11:28 PM »
that was my thought too, i want to see if it could be something easier/cheaper before doing that though

Offline Airboy

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Re: bouncy acceleration with low throttle
« Reply #3 on: February 24, 2018, 01:51:44 AM »
If the primary O2 sensor is crapping out and reading slow, it can cause what you described.

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Offline Gargoyle

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Re: bouncy acceleration with low throttle
« Reply #4 on: February 26, 2018, 09:55:20 AM »
that was something i was going to check, disconnect the primary o2 sensor and see how it responded, but i don't know where the connection under the hood is, do you?

Offline diamondedge

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Re: bouncy acceleration with low throttle
« Reply #5 on: February 26, 2018, 10:01:53 AM »
that was something i was going to check, disconnect the primary o2 sensor and see how it responded, but i don't know where the connection under the hood is, do you?

It should be on the right side of the motor, you can probably trace it back down. I remember it being on that side somewhere.

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Offline RockThePylon

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Re: bouncy acceleration with low throttle
« Reply #6 on: February 26, 2018, 10:11:35 AM »
The sensor is passenger side. Grab a flashlight, you can see the sensor from the top. Follow wires to where it's plugged in.

FYI, driving with the O2 sensor unplugged will foul it up pretty quick. Do it as a quick diagnostic.

Or plug in and see what the sensor is doing.
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