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Discussion Starter · #1 ·
So I’m a scrub when it comes to cars, I bought my 16 wrx because it looks cool and is fun to drive, but anything technical is over my head... hoping someone can help me in layman’s terms... I had a cel come on last week so I took it to the dealership. They asked if there were any symptoms and I told them I was getting no boost. They read the code and said it’s a bad catalytic converter and the car was in “limp mode” which prevented any boost to protect the turbo charger. They replaced the catalytic converter, but when I got the car back I am still getting very little boost, gets to 0psi in first gear, maxes at 5psi in second and immediately drops into the negatives, and about 10psi in third gear. The higher gears seem okay, but I have no power in the low gears. Is it possible that I have a boost leak that would only affect low gears? Or might there be something serious wrong that I need to get checked out ASAP? I have another appointment next week but don’t want to drive it if there’s something else that could really screw it up. This is my baby. Any advice is much appreciated
 

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So I’m a scrub when it comes to cars, I bought my 16 wrx because it looks cool and is fun to drive, but anything technical is over my head... hoping someone can help me in layman’s terms... I had a cel come on last week so I took it to the dealership. They asked if there were any symptoms and I told them I was getting no boost. They read the code and said it’s a bad catalytic converter and the car was in “limp mode” which prevented any boost to protect the turbo charger. They replaced the catalytic converter, but when I got the car back I am still getting very little boost, gets to 0psi in first gear, maxes at 5psi in second and immediately drops into the negatives, and about 10psi in third gear. The higher gears seem okay, but I have no power in the low gears. Is it possible that I have a boost leak that would only affect low gears? Or might there be something serious wrong that I need to get checked out ASAP? I have another appointment next week but don’t want to drive it if there’s something else that could really screw it up. This is my baby. Any advice is much appreciated
You will always make less boost in lower gears. 10 does seem a little low for 3rd how ever I'm more familiar with the old 5speed and the newer 6speed may have a shorter ratio.

My suggestions would to be to check for some type of boost leak. I've not really heard much about the fa20f having issues with it, but it doesn't mean it isn't possible.
 

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How are you measuring boost? Is it on the vehicles built in boost gauge? The one on my wifes '17 FXT always reads low, even WOT in 3rd on the CVT.

If your car is stock, and under warranty, I would want to know why it plugged a CC. Do you have oil in the intake pipes of the intercooler?

Make the stealership work this out if it is under warranty.
 

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Discussion Starter · #4 ·
I’m using the vehicle boost gauge, but before the cel came on I could swear it was higher... I don’t hear the turbo kick in either or get pressed into the seat until I’m in 4th gear with the pedal on the floor. I had the accessport (with 93 octane mapped) in the car until I had to take it in before, fuel ratio sensor was bad, then they gave it back to me with a rough idle, mass airflow sensor had debris in it. Haven’t had the accessport in since September... A guy at work has a 17 wrx so I can get a side by side comparison when I go in today
 

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Discussion Starter · #5 ·
Might be able to test for the boost leak at work too... I’m not really equipped for that but I’ve got a warehouse full of engineers who’d understand what to do lol
 

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I would ask the dealership to do a pressurized smoke test. If I’m not mistaken you should make max boost in 3rd gear with WOT going from ~3k RPM to ~5.5k RPM on a 6 speed standard transmission.
There are articles on COBBs website about what gauges to read on the accessport and where they should be for your make and model. Off the top of my head “TD boost” is one of them.
 
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