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I just got my 2014 S Touring 2.5 Mazda 3 hatchback automatic.

I noticed a slight discomfort when I am cruising to a stop. I can feel the engine braking at about 23mph and another one at 14mph. This is starting to annoy me and I was wondering if this is normal or there is something wrong with my car.

Thanks in advance
 

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I just got my 2014 S Touring 2.5 Mazda 3 hatchback automatic.

I noticed a slight discomfort when I am cruising to a stop. I can feel the engine braking at about 23mph and another one at 14mph. This is starting to annoy me and I was wondering if this is normal or there is something wrong with my car.

Thanks in advance
The transmission is downshifting and this is normal behavior. The reason you feel the downshift more is that when you are cruising to a stop, the transmission releases so you get a slight increase in mpg. This does not happen when you stop quicker as the brakes prevent you from feeling this. But when you are cruising slower without the brakes applied, you feel it more. The automatic has very quick gear changes. Older automatics let the torque converter minimize the downshift. It's sort of like using a manual to down shift and then pushing in the clutch to coast between downshifts.

You will get used to this over time. I don't even notice it anymore.
 

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I just got my 2014 S Touring 2.5 Mazda 3 hatchback automatic.

I noticed a slight discomfort when I am cruising to a stop. I can feel the engine braking at about 23mph and another one at 14mph. This is starting to annoy me and I was wondering if this is normal or there is something wrong with my car.

Thanks in advance
It's normal - it is the automatic trans shifting down through the lower gears as you are slowing down. It will do it worse in "sport" mode too.
Doesn't bother me at all, it has a sporty feel to the trans which I actually like.

My previous car did that as well. It was a 2011 GT Mustang 6spd auto, and around 15 mph when slowing down, the changing of engine breaking as the gears changed caused a clunk in the rear end of the car which was much more annoying and jarring than anything you get in the 3. So I guess for me after coming from that car the M3 is super smooth!
 

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And saves on the brake pads ! As the motor does some braking......... I think the manual May tell you that you can use the sport shift and manual down shift on a real long downgrade when mountain driving which we have lots of her.
 

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And saves on the brake pads ! As the motor does some braking......... I think the manual May tell you that you can use the sport shift and manual down shift on a real long downgrade when mountain driving which we have lots of her.
When the brake pedal is not depressed and you are coasting to a stop, the engine braking does not occur and you can feel the release of the torque converter. Then it downshifts, which you feel, and releases again. This is the computer maximizing the mpg because when the engine is breaking it is using more gas than at idle. It does feel weird, but you get used to it. When you control the transmission using the paddle shifters or manual mode, this does not seem to occur and it feels like you're downshifting with a manual trans.
 

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Something I did not see posted. Along with all the post above the very high engine compression is giving a noticeable difference. If your used to cars with very low compression then you should be feeling a big difference.

While I was driving a friends race car at the track. I kept chirping the tires when downshifting. The race car had the same trans, rear end gear and clutch as my car. But a much higher compression than I was used to. Going from 9:1 to 13:1 compression makes a big difference.
 

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When the brake pedal is not depressed and you are coasting to a stop, the engine braking does not occur and you can feel the release of the torque converter. Then it downshifts, which you feel, and releases again. This is the computer maximizing the mpg because when the engine is breaking it is using more gas than at idle. It does feel weird, but you get used to it. When you control the transmission using the paddle shifters or manual mode, this does not seem to occur and it feels like you're downshifting with a manual trans.
Hi Vrol;
Just a little confused when you said that " when the engine is braking it is using more gas than at idle" and how would that come about ? ;as the fuel injectors are basically tied in with the accelerator and if you foot is not pressing down then no more fuel or am I missing something here ? Thanks
Len
 

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Hi Vrol;
Just a little confused when you said that " when the engine is braking it is using more gas than at idle" and how would that come about ? ;as the fuel injectors are basically tied in with the accelerator and if you foot is not pressing down then no more fuel or am I missing something here ? Thanks
Len
The fuel injection is controlled by your computer, not your accelerator. Your accelerator is an input to the computer. So if the rpm's are greater, the computer is giving the engine more gas even if your foot is off of the accelerator. It's not like the older cars where you have a direct linkage between the gas pedal and the carburetor. So when you are coasting, instead of the engine remaining in a braking mode, the computer disengages the transmission and you are coasting. That increases mpg. This obviously won't happen on a MT car. I understand the theory, but I don't know how effective that programming can be. Mazda engineers evidently thought it would help.
 

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To put it simply, in fuel injected cars, your gas pedal is actually controlling the amount of air you are letting in. the computer then determines how much fuel to give the engine. In a drive bye wire setup, the gas pedal tells the computer how wide to open the throttle and the computer does everything.
 

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To put it simply, in fuel injected cars, your gas pedal is actually controlling the amount of air you are letting in. the computer then determines how much fuel to give the engine. In a drive bye wire setup, the gas pedal tells the computer how wide to open the throttle and the computer does everything.
Actually the gas pedal does not tell the computer how wide to open the throttle, it just requests that you go faster or slower given the mode you are in. The computer then decides the "best" way to get there which is a combination of gearing and throttle. Obviously, if you want to go faster, the computer will open the throttle, and if you want to go slower, it will manage that transaction. However, it is not a direct 1-to-1 relationship like it would be with older cars. That's how the engineers can squeeze a bit more mpg out of the system.
 

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boy did I start something..lol.....sorry tried to keep it simple but here goes. ...... Then if going down hill or costing why would the mileage increase on the Scan-gauge ; to higher mpg ? if I understand
The initial question/statement that the engine requires more fuel when coasting then the mpg should increase ? Don't think so ! Or did I misinterpret the initial statement ?
 

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boy did I start something..lol.....sorry tried to keep it simple but here goes. ...... Then if going down hill or costing why would the mileage increase on the Scan-gauge ; to higher mpg ? if I understand
The initial question/statement that the engine requires more fuel when coasting then the mpg should increase ? Don't think so ! Or did I misinterpret the initial statement ?
You misinterpreted the statement. When you coast, two things can happen -- the transmission is engaged and you get engine braking or the transmission is not engaged and you are freely coasting. On these Mazda automatics, in order to improve mpg, when you coast, the computer determines whether the engine brakes or not. If your foot is not on the brake pedal when the computer disengages the transmission, you get this feeling that the car is surging. If you keep your foot on the brake pedal, you don't feel it. On a manual transmission car, when you downshift, the engine is helping to brake the car. If you wanted to duplicate this on a manual transmission, you would just hold in the clutch when you are coasting. Engine braking requires the car to use more gas because rpm's are higher and the cylinders are firing more. Idling obviously minimizes the use of gas and therefore has higher mpg.

Now do you understand????
 

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Actually, you are incorrect rvoll, when coasting in gear, the computer shuts down the fuel injectors so that no fuel gets fed to the engine saving you more fuel than putting it in neutral and having the engine idle.
 

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Actually, you are incorrect rvoll, when coasting in gear, the computer shuts down the fuel injectors so that no fuel gets fed to the engine saving you more fuel than putting it in neutral and having the engine idle.
I've heard this argument and you are correct that the fuel injectors generally are shut down. If we were going down a hill, I would totally agree. However, as I understand it (and I could be wrong), when you are coasting to a stop and the RPM's get below a specific level (in most cases about 1500 rpm) the ECU starts feeding fuel back into the cylinders so you don't have misfires or predetonation. The amount of fuel used at 1500 rpm is greater than at idle so yes, you are using more fuel IN THIS SPECIFIC SITUATION which is what I was talking about. My guess is that when the computer determines that the fuel must be turned on it looks at the current rpm and the idle rpm and automatically goes to the mode that uses the less fuel. That's why you feel the "surge" when the engine braking automatically stops. You don't get this effect when you are going down a hill because rpms are greater then this level.

I really didn't want to get into the weeds on this issue, so I tried to simplify the explanation. My bad since there are serious gearheads here. Besides, you would never want to put the car in neutral yourself because of lack of control -- it is unsafe.
 

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I agree with not putting the car in neutral. There's an article that someone wrote to test this theory. He hooked up the injectors to an oscilloscope and measured the pluses to see if the car was indeed turning off the injectors when you coast. He observed that the injectors was off until the engine was below 1000 rpms. You could coast for a bit on flat roads or do what some hypermilers do and pulse and coast.
 

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Several people have researched this and it is common knowledge. It is still a strange feeling when coasting to a stop and having the transmission disengaged. I have not felt that in any other car so you feel a "surge". Most people don't coast to a stop so they never feel this. But it looks like the Mazda engineers tried to squeeze out every drop of fuel. This doesn't happen when I'm coasting at 1500 plus rpm. You do realize that at some point when you slow down with an automatic transmission the torque converter is engaged. Right???
 

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Is there any danger of damage in engine braking down hills with our transmission? I have read arguments for both sides (it's easier to replace brakes than tranny, the computer won't let an AT do anything that will damage it so if it lets you it should be fine) so I don't know where we stand with our specific transmission. I don't do it often but on some hilly back roads it's just a lot more convenient to keep it in second gear at about 3,000 rpm and coast than to keep applying the brakes on and off to maintain speed.
 

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Is there any danger of damage in engine braking down hills with our transmission? I have read arguments for both sides (it's easier to replace brakes than tranny, the computer won't let an AT do anything that will damage it so if it lets you it should be fine) so I don't know where we stand with our specific transmission. I don't do it often but on some hilly back roads it's just a lot more convenient to keep it in second gear at about 3,000 rpm and coast than to keep applying the brakes on and off to maintain speed.
I am more in the camp of it being cheaper to replace brake pads than doing any transmission repair.

Of course, more wear and tear does not necessarily equate to repair bills later.

If you like to pick your own gear, a manual transmission might be better for you. Or drive it in sport mode which should minimize gear changes as the car tend to hold a specific gear longer.
 
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