My mazda feels like it is releasing turbo boost early at about 4k rpm. It makes a hissing sound as it builds up pressure and then when it hits that rpm range it drops and continues accelerating super slow, as if I had the turbo removed. Here's some context:

A few months ago I bought a 2019 Mazda CX-5 signature and it was the only one available at the moment (since the signature with the turbo engine isn't sold new on my country) so I didn't have much to compare against.

Ever since I bought it, I always felt like the engine lost a huge amount of power at around 4k rpm but I knew this engine has a big torque drop in that range so I thought it was normal (although a bit excessive). A few weeks ago I was driving in the highway and was feeling the car a bit more aggressive on acceleration, but since I was used to modulating the accelerator so that it shifts gears before 4k rpm I couldn't figure out what it was. It wasn't until about 2 days later that I found out it now felt like it had pressure up until almost redline.

A few weeks after that, it started losing boost again. I had it checked for leaks in the intake piping and found nothing noticeable, and when the car is stopped, the wastegate seems to work normally when revving the engine.

I don't know if anyone else has experienced this or has any idea what the cause could be. Since there aren't many turbo cx-5 here it's hard to compare and I'm trying to avoid replacing the turbo or some of it's components without being sure exactly what the issue is

 

A "feeling" doesn't solve anything in the mechanical world.
To verify you have an actual mechanical issue, you need to take your vehicle to someone who is competent with turbo systems and get your "feeling" technically diagnosed.
I would also point out you can run regular fuel, but you need to run premium (high octane) to get the most power out of the turbo.

 

Thanks a lot for the prompt response!

After experiencing how it behaves when it has boost past ~4k rpm I am completely sure there's an issue. I had it checked but the mechanic couldn't find anything wrong, although he agreed there is something wrong indeed. It makes a hissing noise when the boost drops, like when you release compressed air, and past that, even in second gear it will take ages to get ro redline, like if I was barely pressing the accelerator.

The fuel was my first idea but I always fill up with premium and I even tried fuel enhancers (just in case)

 

If your mechanic doesn't know what it is, then he/she obviously isn't mechanically adept with turbos, or Mazda ones anyway.
You need to take the time and spend the money and get it to a certified Mazda mechanic who does know.
It's the only way you'll know for sure that you will know what is wrong.
Good luck.

 

I never saw that anyone check for engine codes? The trouble or thought trouble with the Turbo would have generated a DTC at least a pending one.
And yes any mechanic that states "I can't find the problem" in my shop would be given notice ! If there is a problem then there is a cause and a solution!

Have the ECU completely scanned in all area's for DTC pending and or permanent and what the status of the I/M monitors are.

 

Could be a problem with wastegate releasing too early. Could also be a knock sensor triggering and slowing everything down. Are you using regular or premium fuel? If on regular, I would try a couple of tanks with higher octane and see if that makes a difference.

 

*WILD GOOSE CHASE
Both would have tripped a DTC or have it available in the ECU to at least point in those directions so *based on the OPs starting information so far ...not likely .