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2003 WRX 4EAT
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Discussion Starter · #1 ·
Hey, I’m pretty new here so bear with me. I’m sorry if this should have been asked elsewhere, or in a different manner.
I drive a 2003 WRX with a 4EAT automatic transmission. Recently, I’ve noticed the boost fluctuates rapidly while accelerating.
Linked below is an example video.
I’m wondering if it’s a vacuum leak, or maybe the boost solenoid failing? Wastegate?

 

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My first question is can you feel that pulsing?
 

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My first question is can you feel that pulsing?
You can see it in the RPMs.

OP -- check the vacuum lines to and from the boost control solenoid. Is it a stock item?
 

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2003 WRX 4EAT
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Discussion Starter · #5 ·
You can see it in the RPMs.

OP -- check the vacuum lines to and from the boost control solenoid. Is it a stock item?
I don’t have the tools to do a proper vacuum check, but I didn’t thumb around the lines last night. As far as I can tell, everything is on solid and I don’t see any signs of cracking.
There isn’t a single mod on this car, not even a tune.
 

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This, to me, is entirely a boost control issue.

Either the control signal is a problem (vac lines) or the solenoid isn't functioning correctly.
 

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Discussion Starter · #7 ·
This, to me, is entirely a boost control issue.

Either the control signal is a problem (vac lines) or the solenoid isn't functioning correctly.
That’s what I was thinking. I read around and came to the conclusion it may be a failing boost control solenoid, or maybe the wastegate actuator? But I’m far from an expert.
Any way I could troubleshoot this myself? Or should I just take it to a mechanic. I usually like to figure these things out on my lonesome, but I’m open to accept if I’m out of my league haha.
 

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Replacing the vacuum lines is easy and inexpensive (take care of the restrictor pill).

Failing that, the BCS is equally easy and also relatively inexpensive.

Those two things are easy to DIY and are at least 75% likely to resolve your problem. I'd start there.
 
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