Engine revving when applying brakes

brandini said:
ABS is only if the tires capability is overcome. If I get nice tires I can easily overwhelm the brakes and then ABS is useless. Engine braking helps absorb some of that energy.

Engine braking also makes sure you are in the proper gear in case you need to accelerate quickly to maneuver as well.
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Really? Your brakes are deficient then. Or your not getting enough force on the pedal. Every car made now has more than the capability to lock all four wheels while on dry pavement. Don't care if you are running slicks. Ability to slow a vehicle quickly is depending on tires, brake responsiveness, suspension, road and weather, among other things.

The reason race cars or sports cars have large brakes is to improve the feel, improve the responsiveness, and reduce the likelihood of brake fade from repeated use.

As to the original question. As others have said, the automatic transmission will keep the converter locked as you slow down if it thinks you are driving aggressively so when you get back on the gas, it responds quickly and you don't have to wait for the engine and transmission to come up from 500 rpm to 4,000 rpm before engaging.
 
CXVille said:
Really? Your brakes are deficient then.
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No, I can lock the wheels up- what made you think I can't? If you put slick, at temp, on a Mazda 3, with stock brakes, the ONLY way to get them to lock is if you unsettle the car so much you unload a wheel and it locks.

Every car made now has more than the capability to lock all four wheels while on dry pavement. Don't care if you are running slicks. Ability to slow a vehicle quickly is depending on tires, brake responsiveness, suspension, road and weather, among other things.
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Most can, but not with slicks at high speed when not slamming on brakes that unsettles the car.

Why am I so sure? Because when I purchase by car I couldn't lock the brakes. Simply wouldn't happen. Had great feel, no lockup. Why? bad pads.

New decent (not anything spectacular even) and rotors and voila. On. A. Dime.

Put slicks on a Prius and then try to lockup the brakes, you'll get a nasty surprise.
 
brandini said:
No, I can lock the wheels up- what made you think I can't? If you put slick, at temp, on a Mazda 3, with stock brakes, the ONLY way to get them to lock is if you unsettle the car so much you unload a wheel and it locks.


Most can, but not with slicks at high speed when not slamming on brakes that unsettles the car.

Why am I so sure? Because when I purchase by car I couldn't lock the brakes. Simply wouldn't happen. Had great feel, no lockup. Why? bad pads.

New decent (not anything spectacular even) and rotors and voila. On. A. Dime.

Put slicks on a Prius and then try to lockup the brakes, you'll get a nasty surprise.
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I can lock (ABS activation) the brakes on our CX-5 at anytime. Done it several times. Perhaps your driving style has glazed the pads over and they no longer are effective? I really don't know.

I've not heard of this issue of stock brakes not being able to lock wheels. Do you have any references for this? Like magazine tests, or something similar? All of my track experience tells me that aftermarket pads and BBK (Big Brake Kits) will result in improved fade resistance, improved feel, and increased component (pad and rotor) life. On the track, stock rotors normally work fine, except they tend to crack under heavy use. Now, many folks mistake improved feel for improved braking capacity, just as folks mistake a responsive throttle for more power, or a louder intake for more power.
 
I don't how you guys think your able to lock up brakes equipped with ABS but if the ABS system and brakes are working properly than they should not lock up because the ABS system will prevent that from happening so you maintain steering control of the vehicle. If you truly are able to lock them up (probably just think you are) than you should bring it in for a service check before you get in a situation where a malfunctioning ABS system might cause an accident. The ABS light should be on if there is something wrong with the system. If you feel a pulsing under the pedal while braking hard (especially in slippery conditions) than its likely working properly and they are not locked up like you may think they are. If they were truly locked up the tires would skid over the road and you wouldn't be able to steer the car in that type of situation.
 
Also gotta remember that brake boosters only help you so much. Even if you feel the brake is slammed to the floor... it can still go more! That's what it took for a mazda 3 I was driving to be able to hit ABS going 30-40km/h. The brake assist wasn't enough power to do it.
 
CXVille said:
stock brakes
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Like I said, not stock. The car has 140k miles now and only the last 5k were me. It had the cheapest pads the chop could find and lovely sticky summer tires because that's how they 'refurbished' a car for sale- crappily, but that's another story.

My driving style had nothing to do with it, as I was never previously the driver, and the pads were new and I even took them and bedded them in to try and rule that out. They got better after the process, but I used to own an 07 Mazda6 and I know what was possible on those same tires.

Brakes can only do so much and are limited by tire grip. If the brake can cause the tire to lose grip with the road- the wheel will lock up. If the tire never loses grip it won't lock up as the road and tire will continue to grip one another, so:
-If you can lock the wheels, the tires are your weakness.
-If you can't lock the wheels, the brakes are your weakness.

With the same tires I can now lock the wheels with new (for clarity, a 2nd set of) pads, from any speed even with initial gentle application of brake pressure as to not upset the car.

And V8 you don't understand how ABS works. In order for it to function, the wheels have to first lockup. It's a reactionary system. If you can't get it to activate, you have weak brakes. If you can, you have weak tires (or poor traction for environmental reasons).
 
V8toilet said:
I don't how you guys think your able to lock up brakes equipped with ABS but if the ABS system and brakes are working properly than they should not lock up because the ABS system will prevent that from happening so you maintain steering control of the vehicle. If you truly are able to lock them up (probably just think you are) than you should bring it in for a service check before you get in a situation where a malfunctioning ABS system might cause an accident. The ABS light should be on if there is something wrong with the system. If you feel a pulsing under the pedal while braking hard (especially in slippery conditions) than its likely working properly and they are not locked up like you may think they are. If they were truly locked up the tires would skid over the road and you wouldn't be able to steer the car in that type of situation.
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You are correct.

brandini said:
... If I get nice tires I can easily overwhelm the brakes and then ABS is useless.
Click to expand...


My point is in response to this quote - any recent stock braking system I am aware of has the ability to lock the brakes or activate ABS to prevent locking. If it won't you have a brake problem.
 
CXVille said:
activate ABS to prevent locking
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Just as long as we're clear ABS only works after the brakes have locked (though it can sense it much faster than humans can react). I agree that the problem would be the brakes, but the 'problem' could simply be size vs grip and not an actual failure anywhere.

Miata guys have the issue with the earlier models with tiny brakes. Wide wheels, sticky rubber, and they just can't take advantage of them. Now it doesn't mean you're getting worse braking performance, better actually, but you're leaving some room on the table if you can't lock the brakes on a modded car.

Phew. Typing online in a way as to prevent assumptions and cover every possible possibility is difficult.
 
I think the new ABS systems never let the wheel actually lock unless you are traveling very slow when you apply brakes. I think they automatically release brake pressure on a wheel when that wheel reduces speed quickly (before it locks) relative to the other wheels. To allow it to lock would heat the tire in one spot (flat spot & creating a lot of rubber burn gas and steam if it is wet, reducing traction) and there is a lot more grip available if fresh rubber is always coming in contact with the road with the wheel turning. It also gives you a lot more steering control.
 
My 2015 CX5 FWD Auto Touring model was purchased 5 weeks ago, and has been in the Mazda repair shop for 3.5 weeks now. While pulling into a parking spot (covered deck, no ice, no water, clear concrete) and my foot FULLY on the brake pedal, the engine suddenly accelerated about 3K rpm and pushed the car against the ABS into the retaining wall. Minimal damage to the front fascia since I was about 4 - 5 feet from the wall when this happened. No, my foot was not on the accelerator. I could clearly feel and hear the ABS engage as the engine revved. Happened way too fast for me to slap the shift lever into N. The dealer contacted Mazda who sent a software update to the ECU 10 days ago. Mazda will not permit the dealer to release the car to me until a Mazda engineer arrives to verify and test it. While I have a free loaner (a CX5 AWD Sport) my confidence in the new car is not solid now. Still waiting to hear from the dealer and or the Mazda engineer.
 
At first I was going to call BS because there's no way an engine can overcome full brakes. But you're saying the ABS engaged and that's how the car had forward motion? ECU update is interesting, but I would think it's more of a sensor issue somewhere. Both, perhaps.

EDIT: Maybe bad sensor sends bad data, but not wildly out of range data, ECU mis-interprets the situation as a result. An ECU update with additional sanity checks would be in order. Gotta sanitize those inputs.
 
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Never heard of this ever happing with a CX5. I think this is just another spam thread by someone with 1 post trying to discredit Mazda. Where are the pictures? You can't come on here as a new member and make such far fetched claims and expect us to take you seriously when this is your fist ever post and you don't even have a picture.

(pics)(spam)(wrong)(getout)(trolls)
 
Likely foot was on gas and brake, it has happened to me as I have big feet. If you are on the brake hard it is harder to tell you are also on the gas pedal. Other cars that had this problem even when drivers did not think they hit the gas were improved by putting more space between the gas and brake pedal and the complaints/accidents went down. OP how big are your shoes?
 
GAXIBM said:
Likely foot was on gas and brake, it has happened to me as I have big feet.
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Agreed. That's the most likely explanation. Or else what V8toilet said! One or the other but there does seem to be a lot of one post wonders with tales that don't seem to jibe with those of us who are regular owners and have not had inexplicable quirks.
 
I think something similar just happened me. My friend just got his car at 4k mile and he said that something similar happened to him. He was at a stop light, or for some reason the the engine started revving up. Then it just launched forward like someone reared ended him. But it wasn't.

I want to get a CX5 as well. Moving away from a honda after a crappy 2000 accord. Sorta scaring me though with this problem. I hope they find a fix.
 
aznromeo4u said:
I think something similar just happened me. My friend just got his car at 4k mile and he said that something similar happened to him. He was at a stop light, or for some reason the the engine started revving up. Then it just launched forward like someone reared ended him. But it wasn't.

I want to get a CX5 as well. Moving away from a honda after a crappy 2000 accord. Sorta scaring me though with this problem. I hope they find a fix.
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Speaking of one post wonders....
 
Engine revving when stopped

MikeM. said:
Speaking of one post wonders....
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This may be a one post wonder but that doesn't mean this is made up to bash Mazda, I love my car and I came across this page looking for answers for the same issue. I will come to a stop and the engine begins to rev. My foot is definitely not on the gas, in fact I practically have to stand on the brake in gear of the car moving forward. This has happened multiple times, this last time they was a loud clunk and the car lurched forward. This is scary and if my wife or kid was driving they may end up in an accident. Does anyone know of a solution? My dealer has never heard of this.
 
There is a switch that tells the car computer you have engaged the brake so it will idle the engine and put the transmission in neutral to save gas if everything is warmed up. Several people have had this fail and it is different from the brake light switch. Get a dealer to check it, also possible to check it with a code reader and the right software on you phone/tablet. You may be able to find it and put a volt meter on the connection to see if it is working if you are so inclined.
 
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