Stick shift - brake release +500 RPM ??

P

Phratt

Member
Hello everyone,

I noticed something on my stick shift CX-5... Canadian version.

Let's say I'm stopped at a light. One foot on the clutch, the other on the brake. The engine is on idle.
When I release the brakes, the RPM goes up 500 RPM for a second or two. Then drops back to idle.

After it's back to idle, I press on the brake for a second or so - then release the brakes, the idles goes back up 500 RPM for a second or so.

WHY?

Thanks for your help...


P.S.: I do not have the istart thing (nor does North American models)
 
Last edited:
Sounds like it's just the vacuum system, that's all. I've never sat in a car where the RPMs didn't vary a little when pumping the brakes at idle.
 
I do not think it's the normal vacuum reaction (+/- 100RPMs)



If I hold the brakes - clutch to the floor, the RPMs are as steady as one can expect.

When I let go of the brakes (clutch still to the floor) RPMs go up +500. If I do not press on the brakes, goes back down to idle 1-2 seconds later.

After it's back to idle, I press the brakes and RPMs react normally (+/- 100).

When I let go of the brakes, clutch maintained to the floor - RPMs jolt +500 for a second or two.


Is this behavior observed by anyone with 6sp Manual Tranny?
A CURIOUS MIND WANTS TO KNOW !!
 
I'm curious too. I wonder if it's by design to minimize the possibility of stalling upon take-off, just a thought...

Can some others with manual trannys report in?
 
Just went on a little ride for some errands...

Upon cold start while the blue light was on I did not notice any of the symptoms you noted. I did notice the RPM level lower gradually while the light was still on. Drove a half mile and tried again while the light was on and did not notice anything.

After a while, a couple miles, I tried at a couple different stop signs/lights and nothing seemed wrong.

Everything seemed normal to me, the idle just varied +/- 100 RPM just like any other vehicle.
 
Hello everyone,

I called my dealer to get some information. Here is what they had to say
  • they say they never heard of this problem
  • they say they do not know this model (CX-5) yet
  • they say it is not supposed to do that
  • they say it might be a tool of some sort
  • they also said that they never heard about istop function
I say they do not know anything about the product they sell !! (bang)
 
Sorry, but when it comes to retail establishments and service-related phone calls, don't bother. Obviously a test drive would be more productive.
 
I had the same issue with my Cobalt SS. Found out it is because the clutch fluid and the brake fluid reservoirs are the same reservoirs. If Mazda has done this then that could be the cause. Kinda got use to it over time. But my cobalt did not do it frequently, once every couple of weeks.
 
Phratt said:
I say they do not know anything about the product they sell !! (bang)
Click to expand...

94461
 
Phratt said:
Hello everyone,

I noticed something on my stick shift CX-5... Canadian version.

Let's say I'm stopped at a light. One foot on the clutch, the other on the brake. The engine is on idle.
When I release the brakes, the RPM goes up 500 RPM for a second or two. Then drops back to idle.

After it's back to idle, I press on the brake for a second or so - then release the brakes, the idles goes back up 500 RPM for a second or so.

WHY?

Thanks for your help...


P.S.: I do not have the istart thing (nor does North American models)
Click to expand...

This would be considered normal only when the car is being started from a cold start and the RPM's are high at startup, you move forward or backwards and apply the brake and the revs drop by about 500 RPM you then take your foot off the brake and the revs increase by about 500 RPM, once the cold start characteristics have finished then the car should not have the 500 RPM fluctuation. The cold start function is mainly to get the Catalytic converters up to operating temp. Thats how it happens on my Manual CX5. Cheers.
 
jnt said:
This would be considered normal... ... to get the Catalytic converters up to operating temp. Thats how it happens on my Manual CX5. Cheers.
Click to expand...

Hi JNT,

That is a real good answer - logical.

After reading the entire thread, I seem to have failed to give out one piece of information about this "thing" - after 30 minutes of stop and go traffic, it still does the +500 RPM when my foot is taken off the brakes.

My CX-5 has 600Km on the ODO.

Any other possibilities? Before I consult those... "knowledgeable" dealerships...
 
Can this be a function of the hill start assist? As you release the brake with clutch down it will help keep you from rolling back as it anticipates you letting out the clutch but have not yet pressed the gas? Are you on level ground?
 
GAXIBM said:
Can this be a function of the hill start assist? As you release the brake with clutch down it will help keep you from rolling back as it anticipates you letting out the clutch but have not yet pressed the gas? Are you on level ground?
Click to expand...

I do not think so... hill assist only kicks in at a certain number of degrees - from what I have seen.
 
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