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2004 WRX Automatic Tranny hard shifts

2K views 1 reply 1 participant last post by  gt420hp 
#1 ·
Just got the engine block replaced due to a broken number one rod. Car has 240 miles on it since the new block was professionally installed. Now, when accerlating about 3/4 throttle from a stop, the car shifts really hard going from first to second. If I keep the RPM's low, light throttle, shifting is smooth.

If I full throttle, it doesn't shift hard.

any ideas of what the issue might be?

Its very noticeable when it happens....
 
#2 ·
Well, strange enough, talked with a local mechanic and he suggested it might be electrical. Sure enough, it appears a subwoofer amp we put in about a week ago is spiking the voltage evidently and causing the tranny to shift badly.

We disconnected the newly installed amp, and the problem has gone away.

Never knew that could be an issue....
 
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