My daughter has encountered twice where her 98 Honda Civic (in extremely hot weather and stop and go traffic) where her brake pedal can be pushed to the floor **AND** right after that the engine revs up high.
I couldn't figure out HOW they could be related but found there is a vacuum hose going to brake booster and I dont know much about cars but thought vacuum issues could cause engine racing? I tested the brake booster per the manual and it seemed ok (although it wasn't hot).
What could be going wrong when it gets really hot out and otherwise the car is fabulous. I had to swap cars with her so she woudn't be driving it.
This is REALLY weird !!
I would really appreciate any suggestions on what might be wrong or how to troubleshoot.
Thanks in advance !!!

 

I checked for vacuume leaks using carburetor cleaner and spraying near vacuum hoses...and then engine did not speed up at all..


Please any ideas ?

 

If the brake booster leaks, the engine will rev high. Start the engine, press the brake pedal hard and hold it, see if it has any tendency to sink. Replacing both the booster and the master cylinder should be considered.

 

Hi...so I did that brake booster test and it did not go down...my question is whether it would matter if its not in the same environment (100 degree stop and go traffic) since I tested in my garage on a nice day ?

 

so now to sound like a dumbs**t ....after talking to the Honda dealer he prompted me to ask more questions of my daughter ..after doing so ..its sounding more like under the extreme heat the engine started racing and she just had to press harder on the brake to make it slow down. When she got the car stopped and put in park, the engine would race to 4K RPM. She turned car off and back on and the car still raced to high RPM. Only after sitting for a few hours, when she started it, it did not race.
So I dont think the brake pedal was going to the floor she just had to push much more to counteract the engine...
so the million dollar question is what would cause the engine to increase RPM in stop and go traffic when extremely hot (in fact that day the highway was buckling from the heat.
I'd like to change title from Hot Outside->brake pedal to floor->engine revs high to Hot Outside->engine revs-> hard to stop car with brakes but I don't know how.

 

I dont have an answer but I have the same problem on my 98 EX auto 2 door and would also like to know. I thought at first it was my A/C running that caused it but it does it when its off. I was told possible the Idle Position Sensor?? Just had A/C recharge, speed sensor replaced, window fixed and timing belt replaced. Ok guys ideas?

 

Brake pedal falls to floor and idle speed increases?

 

I should alsi mention after driving and its idling high when i put it in park rpms go up to 3000-4000 and sometimes fluctuate up n down constantly until I shut the car off. When I start it back up its still racing but I have to fight to get it into gear. HELP!

 

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So my original post was based on what my daughter told me ....which I misunderstood...
so the real problem is engine idle RPM accelerates in HOT weather to between 2K-3.5K when it should be at 1K.

Is that the same for you (Codercrzy) ?

So if I get to happen again ..Im going to stop quickly and squeeze hose to brake booster and see if that stops engine from racing....

any other ideas ?

The problem is it has to be very hot and its intermittent