BMW M3 Throttle Issues After Bad Mechanic Visit

I had nearly identical issues with my 2015 BMW M4 last year. The symptoms matched yours perfectly, hesitation, hissing, rough idle, and increased fuel consumption. After getting it checked at my regular mechanic, they found that the intake boot had several cracks and was leaking. The rubber had deteriorated over time, creating vacuum leaks. It wasn't a majorly complex repair, but definitely not something to ignore since it was affecting engine performance and could potentially cause more damage. The fix involved replacing the intake boot and checking all the surrounding clamps and connections. While they were at it, they also inspected other rubber components in the intake system since these parts tend to wear out around similar intervals. The car ran like new afterward, smooth power delivery, stable idle, and back to normal fuel consumption. I'd recommend getting it checked soon since intake leaks can cause additional problems if left unaddressed. Just make sure to go to a reputable BMW specialist who can properly diagnose and fix the issue.

Thanks so much for sharing your experience! This definitely sounds like what I'm dealing with. The symptoms match up exactly with what my car is doing. Really good to know it was just the intake boot in your case. Would you mind telling me roughly how much you ended up paying for the repair? Also curious if you've had any other issues pop up since getting it fixed?

Hey there, glad I could help! Just wanted to follow up. Yep, got it fixed at my regular mechanic and the air intake system leak was indeed the culprit. The total bill came to 100 € for replacing the leaking intake hose, which honestly wasn't as bad as I feared. And to answer your question, nope, haven't had a single issue since the repair. The car's running perfectly smooth now, just like when I first got it. The fuel economy is back to normal, no more hissing sounds, and the throttle response is crisp again. Really night and day difference! Trust me, once you get this sorted out, your M3 will feel like a different car. Those vacuum leaks can really mess with performance. Just make sure whoever works on it knows their way around BMWs, it makes all the difference.

What a relief! Thanks for the detailed follow-up. Really wasn't expecting the repair to be that affordable, I'd budgeted way more in my head! Just took it to a certified BMW shop yesterday. You were spot on, they found cracks in the intake boot. They're fixing it tomorrow, and quoted me slightly higher than what you paid, but still reasonable. The mechanic showed me the worn-out parts and explained everything clearly, which was refreshing after my last experience. Can't wait to get my car back to its normal self. This whole ordeal taught me a valuable lesson about choosing the right mechanic. Next time I won't try to save a few bucks by going to that sketchy shop. Really appreciate you sharing your experience, it helped me avoid potentially getting ripped off again!