I have a 1994 Honda Accord EX. In December, I left it sitting for 3 weeks while I was home for the holidays, and when I returned the brakes started acting up. After my car has been sitting for any long period of time – 1 week being the shortest noticed – when I press the brake pedal, there is a vibration. It doesn’t feel like ABS, more like if my wheels were out of balance.
After I initially noticed this problem, my brake pedal would also just keep going to the floor when I was stopped at a light. I took it to a mechanic, and they could not reproduce that, so they did not want to replace the master cylinder. They flushed the brake fluid, and after the weather warmed up, I have not noticed this problem anymore.
It still feels like my wheels are out of balance when I brake, but I know they are not since I just got new tires and have had them aligned, balanced, etc. The problem is significantly worse when the car has been sitting for a while.
You may have had water in the previous brake fluid.
The weird braking sensation may be a result of [normal moisture caused] rust build up.
The brake pedal going to the floor under constant pressure may be from air in the system.
When they replaced the fluid they may not have bled all the air out of the lines.
It may be warped rotors according to many who visit here, but the first thing I would do is make a couple of hard stops from 70 or so. Hard stops but not to the point of wheel lock.
I just had the rotors replaced, so I can’t imagine that they would be warped.
I’ve definitely made hard stops from those speeds. Is that supposed to fix the problem?
Since you’re making hard stops from 70-80 mph (why?) then it’s quite possible you could have heat warped rotors.
Since the car is a '94 model with ??? miles, it’s also possible that you could have a loose wheel bearing or worn suspension component such as a tie rod or ball joint, which could also cause it.