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Cause for having to double-pump brake pedal to get good performance?
Over the past few months, my 986 brake pedal had became increasingly spongy. I bled the brakes and found bubbles in the two front calipers (the two rears were fine). After bleeding, the pedal was nice and hard with the engine off. When I started the engine, the pedal became softer, but was still harder than before bleeding. On the road, while things had improved, I still felt the pedal was too spongy and found that I could get much better braking performance by double-pumping. It doesn't matter if the brakes are hot or not, double-pumping always gives better braking than a single pump. Rotors and pads are in great shape, so it's not them.
Two questions:
- Does this sound like I still have air in the lines or could this be a master cylinder problem that is requiring the need to double-pump?
- Is the fact that the pedal softens when the engine starts normal and expected (due to the vacuum assist) or should it remain as hard as when the engine is off?
TIA!
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