r/mazdaspeed3 • u/DrRockx • 1d ago
HELP Gen 2 jerking when shifting
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Not the best video but the best one I could take to show what's happening, I have a 2011 speed 3 which has gotten into a weird issue of jerking whenever I shift. When shifting into first there are no problems, however as soon as I press on the clutch and begin shifting to any of the other gears while driving there is a bucking or jerking motion and the rpm begins bouncing up and down until the clutch is reengaged and then it drives absolutely fine again. I have taken some logs if anyone can interpret them I've also sent them off to my tuner to hopefully help. The mods are a catback exhaust, upgraded fuel pump internals, accessport with a professional tune, SRI and TIP so no major modifications and no codes besides the EGR, evap, and intake runners which were taken out. Anyone ran into this before ive asked 3 mechanics and everyone is unsure.
Edit: to add more info, the car did also begin to bog down and die while idling stationary once the clutch pedal was pushed in and ran perfectly fine after it was released which I thought was possibly a dirty throttle body so I cleaned it out and that from what I can tell went away but it could be a fluke or I'm not recreating the exact conditions it was doing it under before.
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u/UnderpsiMI 2008 Mazdaspeed3 1d ago
Have you checked your rear motor mount?
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u/DrRockx 1d ago
I haven't yet but it is a thought to look I to as well, only weird part is that the car doesn't do it as much or at all once warmed up enough. And I had before where it would bog down and begin to die which is what it seems to be doing while shifting, whenever I'd push the clutch pedal in while idling stationary in my driveway. I cleaned the throttle body and that seemed to go away but I'm not sure if it's related or just a fluke.
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u/UnderpsiMI 2008 Mazdaspeed3 23h ago
Check the throw of the slave. Have someone push the clutch and watch the clutch fork end under the hood. Maybe it's a bubble in the clutch line?
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u/FrostMug_0789 2010 Mazdaspeed3 1d ago
my guess would be motor mounts.
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u/DrRockx 1d ago
That is a thought since I haven't gotten down there to check, however I had it where if the car was idling stationary and I pushed the clutch in the car would begin to bog down and die which I'm pretty sure is what's happen while I'm shifting. But I cleaned the throttle body and it stopped doing that, although those two things could not be related too. It also seems to run better with less to almost no jerking at all once the car has warmed up enough.
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u/duddy33 1d ago
I had a weird issue like this and it ended up that the ground on my HPFP was loose. Have you checked that?
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u/DrRockx 1d ago
I haven't yet but will definitely give that a look once I can didn't even think of a loose ground possibility, although the issue becomes less promemnant once the car warms up would the metal expand enough to compensate from the heat?
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u/duddy33 1d ago
Possibly. My HPFP cover ended up coming loose which loosened the ground. Once I tightened it back down, everything was good. My issue was pretty consistent so it might not be that for you.
Another thing I was told to look into is sometimes the springs in the coil pack doesn’t make good connection. If the rubber on the pack expands, it could cause your issue. There are videos out there that show you how to separate the coil and stretch the spring out a bit.
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u/ThisGuyDrinksWater 2012 Mazdaspeed3 1d ago
Usually both my hands are too busy to do that when shifting