My brother's car has a very rough idle and misses on cylinder 1 and 2 sometimes. We cleared the trouble codes and this solved the problem. But now the brake pedal is causing trouble. It’s very hard to press down on. It won’t go down and there is a hissing noise coming from the brake pedal, too. What’s causing this?
Hello. This is caused by a bad brake vacuum booster. When the booster fails, the brakes will get hard and it can cause a vacuum to leak in the engine causing a misfire. It sounds like this is what is happening as the booster is powered with engine vacuum. If you need to have this looked at, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose the brake pedal problem and perform appropriate repairs.
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