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philippstern7

BMW M4 Engine Stalling & Power Loss Mystery Needs Solving

Check engine light on

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Stalling while idling

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Loss of engine power

Hey car enthusiasts, having some trouble with my 2014 BMW M4 (118,539 KM) and need your input. My check engine light is on, and the engine's been acting up, power drops, stalling at idle, and struggles to maintain steady RPMs. Feels like the throttle isn't responding properly either. A previous mechanic suggested it might be the fuel volume regulator, but after a bad experience with them, I'm hesitant to go back. Has anyone dealt with similar symptoms in their M4? Would love to hear about your experiences and trusted mechanic recommendations. Thanks in advance!

4 comment(s)


ralfsilver8

Hey there! I had nearly identical issues with my 2016 BMW M3 last year. Those symptoms you're describing, power loss, stalling, and inconsistent RPMs, perfectly match what I experienced when my high-pressure fuel pump (HPFP) went bad. Had it diagnosed at my regular BMW shop, and sure enough, the HPFP was defective. It's a known issue in these engines. They had to replace the entire pump unit. The repair took about a day and a half, they needed to clear the fuel system and recalibrate everything after installation. It's definitely not something you want to ignore or delay fixing. A faulty HPFP can cause serious engine damage if left unattended. In my case, I was lucky to catch it early before it caused any additional problems. Your symptoms are textbook HPFP failure rather than just a fuel volume regulator issue. I'd strongly suggest getting it checked by a BMW specialist who's familiar with these engines. Hope this helps!

philippstern7 (Author)

Thanks for sharing your experience! That HPFP issue sounds exactly like what I'm dealing with in my M4. Really helped narrow down what might be wrong. Quick question, do you remember roughly how much the repair set you back? Also, has everything been running smoothly since then, or have you noticed any other quirks pop up? Just want to know what I might be in for.

ralfsilver8

Hey again! Just wanted to follow up, got my car fixed and you were spot on about the HPFP! The whole repair ended up costing me 1510 € for the high pressure pump replacement. They also found and fixed the fuel volume regulator while they were at it, which was definitely defective like that first mechanic suspected. My M3's been running like a dream since the repair, no more power drops, stalling, or any of those annoying symptoms we discussed. It's honestly like having a new car again! The throttle response is crisp, idles perfectly, and the engine feels so much smoother overall. Haven't noticed any other issues pop up since the repair, which was about 6 months ago now. The tech did mention these pumps typically last a good while once replaced, so you shouldn't have to worry about this particular problem again for quite some time. Hope this helps with your decision-making! Let me know if you need any other info about the repair process.

philippstern7 (Author)

Thanks a ton for all the detailed info! Just got back from the mechanic yesterday, and you were absolutely right. Took your advice and found a BMW specialist, turns out it was indeed the HPFP. Funny enough, my repair bill came in pretty close to what you paid. The mechanic was super thorough and spotted a couple of minor issues too, but nothing major. They got everything sorted in about two days. Took it for a good test drive today and wow, what a difference! The car feels completely transformed, smooth idle, perfect throttle response, and that signature M4 power is back in full force. Really appreciate you sharing your experience, saved me from a lot of potential headaches and helped me make the right call. Feels great to have this sorted out properly. Thanks again for steering me in the right direction!

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