Idle Drops When Brake applied - Can anyone Help??

[wifescar]

Hello to Everyone,

I am a new member and have come across this web-site on google. I am posting here today because of a problem with my wifes 06 Mazda 3 GT. Here I go.

My wife owns a 06 Mazda 3 GT. It has 99,000 km on it. About 1000 km ago i noticed that every time i would drive it and come to a complete stop at either a stop sign or red light, the idle would drop and the car would shake as well as a small noise from the engine.

When i would release the brake pedal the Idle would go right back to normal. When the car is in park the idle is normal. Only when the brake is applied and the car is in gear.

So i figured i would change the spark plugs. No change at all. So i took it to Prima Mazda and Nev the rep there said they have never heard of such a thing. I find this hard to believe.

There is no check engine light. So i started to check things myself. I tried to see if it was the coils. So i had a friend of mine come over and place the car in gear with the foot on the brake and i started unplugging the coils. The car reacted as it should have and ran very rough. I found it strange that the check engine light never came on.

I cleaned the throttle body thinking that it may be sticking and still no differance.

So i started asking around at different shops and the only thing i can think of is the brake booster?!?!

It seems that i may be losing vacuum. I dont here and leaks but like I said this only happens when the brake is applied.

Could there be a small vacuum leak within my brake booster??? Has anyone else had this problem or is having this problem. can anyone help?

I am concerned as my wife drives our 5 month old baby in this car and am afraid that it may stall on her and i can not afford to have the dealership play stupid and rape me on this repair as they have in the passed.

Any help or suggestions would be extremely helpful.

thank you for your time

P.s. I also had the e-brake light come on about 1 year ago and it remains on. The brakes are all new and the fluid level is perfect. Any ideas?

[CanSpeed 3]

Im actually fighting the same problem but it doesnt seem to matter so much when the brake is pressed, more when im slowing to a stop and putting it in neutral after moving (ie coming to a stop light, and near stop) It also happends at idle. Ive done a few things that has helped but yet to fix the problem.

1) Ive put a brand new purge valve in since it was the main reason to cause rough idle. (helped but still doing it)
2) cleaned throttle body
3)clear MAF sensor (helped a bit)
4) switched to 89 octane (runs a lot better. Some ppl say you'll never notice it but they are very wrong.)
5) reset ecu
6) new plugs

Another thing to think about is i have Motor mods done and ive noticed this more after i put my exhaust on. Could be a lack of back pressure issue but i doubt it. Just like you said... No damn Check engine light. My motor is a 2.0L

Ive talked to the mechanics at mazda and its like they've never had these complaints before. It seems to be a cold weather thing in my opinion. This never happends in warm weather. Im honestly out of ideas. It wont be a coil issue.. if i coil is going to die, it just dies.

[mazdaskit]

mine did that today it only does it sometimes and only when im stop and goes to 500 rmps and shakes then goes to normal rpms

[Default User]

Sounds like a vaccuum leak. Not neccessarily with the booster, otherwise pedal would feel real spongey/ no resitance at all.
MZ3's have horrible rear brakes as it is.

I assume your wife's car is auto...
Have her press the brakes and check under the hood for any noticeable hissing, weezing, etc.
check this also in P, R, N, and D.
Watch the motor movement also. MZ3's also have lousy mounts which can cause a leak, with all the movements.

[wifescar]

mine did that today it only does it sometimes and only when im stop and goes to 500 rmps and shakes then goes to normal rpms

Well when it started for me it happened on and off. but now it does it all the time. It doesnt matter if its cold or hot. And Now i will come to a stop it will idle nice and 15 seconds later it drops to 500 rpm and stays there until i let go of the brake.

I wonder if there is or should be a recall on this??

Like i said before prima mazda is the first place i went as that is where my wife bought the car and they say they never heard of such a thing. i then took it to 2 other dealers and 1 dealer says i need a complete ecu flash and the other says they need to hook it up to start figuring it out. But there is no check engine light so i cant figure out why he needs to scan for codes.

[wifescar]

Sounds like a vaccuum leak. Not neccessarily with the booster, otherwise pedal would feel real spongey/ no resitance at all.
MZ3's have horrible rear brakes as it is.

I assume your wife's car is auto...
Have her press the brakes and check under the hood for any noticeable hissing, weezing, etc.
check this also in P, R, N, and D.
Watch the motor movement also. MZ3's also have lousy mounts which can cause a leak, with all the movements.

its funny that you mention this as while i was in the garage today looking it over with a mechanic, while i had the brake down while in gear, the idle dropped and after like 1 min or so, the brake pedal went all the way to the floor!!!

In my original post i had also mentioned that my e brake light remains on while the hand brake is down. its been like this for awhile now. I wonder if this has anything to do with it.

[m_bisson]

Turn the vent setting to floor only and see if the problems stops. The a/c automatically turns on/off if you have it blowing at the windows, even if the a/c button itself is not lit up. If there's a problem with the a/c pump it can cause a jerkiness in the idle when it engages/disengages.

[r4BBiT]

I definately sounds like vacuum leak, especially without any CEL. I also heard about spraying carb cleaner on vaccum hoases, so if there is a leak will suck it in and revs should jump up.

[standsideways]

Sounds like a vaccuum leak. Not neccessarily with the booster, otherwise pedal would feel real spongey/ no resitance at all.
MZ3's have horrible rear brakes as it is.

I assume your wife's car is auto...
Have her press the brakes and check under the hood for any noticeable hissing, weezing, etc.
check this also in P, R, N, and D.
Watch the motor movement also. MZ3's also have lousy mounts which can cause a leak, with all the movements.

very good!

also check your maf....my intake did that untill i put a 2 3/4" sleeve in it.

[hellbag]

Hi CanSpeed 3 & wifescar...
My husband and I are having the same issue . I have a 2005 Mazda 3 GT w/ 84000 km. I use it mainly for city driving with the occasional long trip to TO or even to Florida.
In my case, when I idle at a stop sign/light the car rumbles/shakes on and off. Yesterday, while traveling from TO to Ottawa, the engine light appeared for the whole trip. The rumbling was quite noticeable so we stopped for lunch. After lunch, we decided to drive the car at 80 km back home, as the car manual dictated (don't drive at high speeds when light is on). The cycling on and off sound continued throughout the trip.

I'm waiting to talk with the service manager, but after reading these forums, I think I am going to ask the dealer to do the following diagnostics:

1. Check engine mount
2. Inspect/change purge valve for leak
3. Look to see if a/c system is causing RPMs to spike (my a/c was on for a bit of the ride, because I was too hot in my winter clothing)
4. Look at Emission Control System

Anyways, if anyone else has any good advice. Pls post. I will let you know if all goes away...

Btw, I have brand new Toyo winter tires, my 4 season tires are also new. I'm due to replace my brakes in the late spring as well.

[Donutz]

Let us know what the code is for the check engine light.

[CanSpeed 3]

Yes please make sure you get the code for the rest of us, and find out exactly what they replaced.

[hellbag]

Just got called from the Dealer. They checked out the purge valve and the engine mount and they were fine.

The technician has proposed changing the oxygen sensor and we are ordering a part from Toronto.

All told, with the diagnostic, this will cost me $400 + dollars. Ouch...

Will go back to the dealer tomorrow to install it as the part will arrive tomorrow.

The Oxygen Sensor is part of the Emission Control System in the car. The manual says that if you see the "check engine light" then one of the four scenarios is a problem with the Emission system. So perhaps he is right (I hope he's right!)

This is what I can find out about the oxygen sensor's role in the car: http://www.youtube.com/watch?v=4G6LiALLOEc

Once this is fixed, I will monitor this situation to see if it's really fixed.

[wifescar]

I have taken the car to another shop today and they cant figure it out. So I am at the point to have the dealer just give it to me and have them figure it out. Its funny when i was at the dealer and asked the question and told them about what the car is doing, they just looked at me as if they have never heard of such a thing. I just cant figure this out.

I tried cleaning the throttle body again and now when i start the car it revs high and slowly goes down.

[sas]

Not much, but you can determine the nature of the problem. Remove the horn fuse
and try the brake pedal at idle again. The PCM takes the brake signal from there.
If Idle is still changing then it’s the booster, if not then the engine management.
You should to know, with removed fuse you do not have the brake lights.
Can’t say what you’ve done with the throttle body.

[mazdaskit]

I got my break lines flushed today & throttle cleaned out and it seems not doing it anymore **knock on wood** so i dont know if that did anything

[CanSpeed 3]

I have taken the car to another shop today and they cant figure it out. So I am at the point to have the dealer just give it to me and have them figure it out. Its funny when i was at the dealer and asked the question and told them about what the car is doing, they just looked at me as if they have never heard of such a thing. I just cant figure this out.

I tried cleaning the throttle body again and now when i start the car it revs high and slowly goes down.

High revs on startup could be a problem with Maf airflow sensor, or atleast it would be the first place i check. Maybe a loose wire or dirty sensor. See if you notice a difference when your air is turned on or off. Just curious.

[gopisidhu]

Hay Hellbag can you tell us if your problem is fixed as my car is doing samething.
Thanks

[Prima Tech Aaron]

Few things in this thread I wanted to reply to.

On cold start up the car will fast idle until it is up to operating temp. This is normal operation

When the a/c cycles on (with defrost as well) the engine idle will drop and pick up due to increased load then idle adjustment.

There is a PCM for some Mazda 3s for idle problems. PCM updates shouldn't be done unless you have the concern. It could create problems through adjustments ment to solve other issues.

I do see cars with idle concerns due to carbon build up in the throttle body.
The maf can be cleaned at the same time. (rec. Brake cleaner)

if it was a vacuum leak, engine light would set (possible p2187 lean bank one or p2188 lean at idle)
gas mileage would be affected. Etc.

Just a side note. I have recently moved from Prima to maple Mazda.
These are just recemendations an educated guesses. I'd really need to see the car to properly diagnose.

Hope this helps.

[hellbag]

Hi there everyone...

The dealer replaced the oxygen sensor and the car is running fine now.

Not sure why you wouldn't go to the dealer and do a diagnostic rather than take it to other autobody shops. Is it because of the dealer costs?

Helen

[hellbag]

My problem was a clogged oxygen sensor.

Oh yes, and here is the info...

LF66-18-861C Oxygen Sensor - Part cost $243.04

[Zoom Zoom Boy]

Hi there everyone...

The dealer replaced the oxygen sensor and the car is running fine now.

Not sure why you wouldn't go to the dealer and do a diagnostic rather than take it to other autobody shops. Is it because of the dealer costs?

Helen


If you're in warranty, then take it to the dealer for sure.

If out of warranty, then another shop such as Street Performance is much cheaper than the dealer and a lot less hassle too. Also, many members have modified cars. A lot of dealers will simply blame the mods for the problem, even if they really aren't related and then charge for the diagnostic even in warranty. That is what I mean by 'hassle'.

BTW- did you ask for a TM3 discount on the oxygen sensor? The discount is 15-17% at participating dealers.

[hellbag]

No, I did not, but I will call and ask them....

[mellimello]

hey wifescar, did you ever get a fix because i have the SAME problem, exactly.
i've got an automatic 2004 mazda3 GT sedan.

let me know.
i'm supposed to drop the car off at the dealership monday. i've got a week left on my warranty. this is a problem they've supposedly fixed before by flushing fluids etc. but nothing has worked!!

thanks!!

[wifescar]

Just an update. the Dealer has no idea what is wrong with the car. The only thing they are saying now is that it needs a software update. My question to them was, should this not be a RECALL if peoples cars drop idle when stopping? Why was I not sent out a letter saying that there is a software up date and I should bring it in? I am at $400 already and counting.

[TheMAN]

it all still sounds like a problem with the brake booster to me... some of them do go bad!

[LiviuTincu]

did you fixed your problem? I have exactly the same issue and I'd tried fixing different things and nothing has worked. Could be a brake booster or its check valve ? :(

[TheMAN]

if the check valve has gone bad, you'll just have a firm pedal after you mashed on the gas... it wouldn't cause idle drops


P.S. this thread is almost 8 months old, the guy probably had it fixed by now

[kckev99]

its funny that you mention this as while i was in the garage today looking it over with a mechanic, while i had the brake down while in gear, the idle dropped and after like 1 min or so, the brake pedal went all the way to the floor!!!

In my original post i had also mentioned that my e brake light remains on while the hand brake is down. its been like this for awhile now. I wonder if this has anything to do with it.

That sounds scary.... you may want to check the brake fluid level. Brakes should never go to the floor unless there is a loss of pressure in the brake system.

As for the idle problem does it happen when in Neutral without pressing brakes? Is the problem solely related to pressing the brakes?

Other things to consider if your car has a lot of mileage:
- valve adjustment (not sure if this is necessary for a Mazda 3)
- EGR cleaning (consider this if your car burns oil, I've heard that the M3 engine tends to burn oil especially if you run recommended 5W20)
- Possible low oil pressure... maybe trying oil with higher viscosity like 5W30 or 5W40
- just do a fuel and intake cleaning.... Motul has a complete cleaning system. You can ask your mechanic about it

[mido]

I get this too but never thought it was a problem ive gotten used to it. How low are the rpm dropping?

[TheMAN]

let this thread die already ffs