weaken brake with cold start?

[thomson]

I wonder why when I start the car and drive right off (like only leave the car idle in 30s), then when I travel to the first stop light near my home, the brake seem to be harder to press and the braking distances seem a bit longer than normal. This does not happen when the engine temperature up to normal temperature (i.e middle as shown in the temperature gauge)

I think it may be the transmission doesn't operate as it should when in the engine is cold? Cause I can feel the car wants to go ( so the brake is harder to press?) even the rpm stay at 1000. And when I leave off the brake after holding it firmly, I can hear somewhat loud sound (sounds like the brake is stick to the wheel before? actually i think it's the same sound when I let off the brake after holding it sometime with the car on a downhill road )

[Cyorke]

sounds like the power vacuum booster is not operating correctly or something along those lines. maybe some kind of vacuum leak or something like that. That is about the only thing I can think of that would cause hard braking.

You shouldnt be ahving problems though with that new of a car.

[kamesama980]

as for the high idle and harder to stop at the first stoplight... thats normal. when you start the car, it automatically idles a bit high till it warms up. hence why all diagnostics say "once the engine has warmed up..." normally the brake booster starts working about 1-5s after starting the car even on my 18 year old cressida, depending on the temp and how long its been off. the brake booster might be poorly fitted, and doesnt loosen up till the whole engine bay gets warm.

my car idles about 1500 and slowly falls to 650 normal over maybe 5 minutes. at least yours is FWD, my cressida is RWD so when i get the high idle in icy/snowy conditions its really fun. the rear wheels get less braking power and more going power. hence, coming to a stop in really low traction, the front wheels can lock up at the same time the rear wheels are spinning forward w/o traction. thats a fun way to come up on a busy intersection. so i use neutral when stopping on ice/snow till the engine warms up

[thomson]

well the high idle only happens when the car is in P gear

once I drop to D, it will drop to 1000

so there's no high idle problem (better say high idle is not a problem, it's more like a feature i think lol)

the only "problem" or weird thing is the car seem harder to brake if i didn't let the car idle for a bit longer before dropping to D (i.e to 1000 rpm)

may be like kamesama980 said the brake booster isn't working at it best with the car in cold start?

or the other thing i can think of is the torque converter has a tendency to push power when the car in cold start lol (sorry but I am not quite sure how the torque converter work) I am thinking is that because of the high idle, the torque converter tends to push power to drivetrain once it is connected to the drivetrain?

[tarbasd]

It is the same with me, but I think it is normal. Until your engine is hot, your idle is higher. That is also true in D. The reason that you experience a drop in RPM when shifting to D is that your engine works againts your blocked wheels and the torque converter eats the excess energy. The car wants to go and it it wants to go stronger when your idle is high.

Also, another guess that the brake pads are designed to warm/hot conditions, so the grip may not be that strong until they warm up.

If you ever had brake or electrical malfunction, you know how it feels when the brake boosters do not work. This is not that.

[Alloy]

i dunno much about cars, but for my gen 5, is a bit of the opposite, i think the brake is stronger right after i start my car, especially in cold weather, I actually hope the brakes can always be that strong. haha.

[Hajoca]

Higher engine speed, less vacuum is available in the intake manifold to boost the braking force.

Check the brake booster hose, there is a ceck valve in it (so air goes one way only) and look for condensation, cracks, and how well it fits back in etc.

[VVT-i Owns]

Brakes takes a few stops to get to optimal operating temps.