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Discussion Starter #1
Hi All

This is my first post and I hope you can help me out here.
I bought my first Mazda ever like 1.5 months ago.
Its a Mazda 3 2.2 from 2015 with 150 HP


The problem is... I lack power - especially in higher rpm's.
I went to a dealer yesterday and they read the ECU but they couldn't see a error code or nothing.
So they did a maintenance on the car. ( oil filter, fuel filter, new oil, etc..)
They also did a test drive ( without me) and they claim they don't see anything wrong with it.

So yesterday after getting the car back I filmed the acceleration.
I took me 11 seconds to get to 100 Km/h.
Doesn't matter how I shift or what RPM i shift - it remains wayyyy to long.
But I feel a difference between the lower rpms and the high ones.

I know that the car has sequential turbo's and the second one kicks in ( fully ) around 3000.
Maybe that's where it goes wrong?
Some kind of sensor or waste gate or whatever that isn't working properly?
I have no warning signs on the dashboard.

See below the link to the acceleration vid:

 

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I think you need to look at the power / torque characteristics of the engine to explain what you are experiencing.

The engine reaches its maximum torque at 1800 RPM. It keeps this reasonable constant until around 2500 RPM. At this point the maximum power is almost reached. From this point onwards the power stays constant and the torque drops of until 4500 RPM. At this point the power and the torque both drop off quite fast.

Basically, this means that there is no point going above 3000 – 3500 RPM. Change up a gear and let the torque do the work. After 4500 RPM it is really is over and out.

This I think explains the difference you are noticing between low and high revs. With a turbo diesel everything happens at low revs.

For maximum acceleration you need to change up at the point where the revs drop to 2000 RPM in the next gear.

Hope this helps,
Andy
 

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Discussion Starter #5
I think you need to look at the power / torque characteristics of the engine to explain what you are experiencing.

The engine reaches its maximum torque at 1800 RPM. It keeps this reasonable constant until around 2500 RPM. At this point the maximum power is almost reached. From this point onwards the power stays constant and the torque drops of until 4500 RPM. At this point the power and the torque both drop off quite fast.

Basically, this means that there is no point going above 3000 – 3500 RPM. Change up a gear and let the torque do the work. After 4500 RPM it is really is over and out.

This I think explains the difference you are noticing between low and high revs. With a turbo diesel everything happens at low revs.

For maximum acceleration you need to change up at the point where the revs drop to 2000 RPM in the next gear.

Hope this helps,
Andy
Yeah I will try to shift earlier but what about this? ( Not mine)

If you compare the first test with the second one, it remains basically the same.

 

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@Roberto N. Based on the charts posted by Mazda Three, assuming you also have that ECU map, and assuming drop of ~ 1500RPM when changing gear, you want to shift at ~ 4500RPM for best performance.

Your initial video shows going to high revs beyond the effectiveness of peak speed performance. Additionally, your gear shifts are very slow. Even with that, I would have expected at most 9.5, but 11 is too much.

Based on my recorded videos from when my car had the standard ECU map back in 2015 it accelerated from 50km/h to 120km/h in 3rd gear in 10seconds. From 50km/h to 140km/h in 3rd gear it took 15 seconds. You may want to do this test to eliminate dead start issues and shifting issues, and then compare it with the time I posted.

Please perform the tests in safe environment and on a road where such speeds are allowed.
 
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