M4 Symptoms: Fuel Pressure Regulator or Something Else?

Hey there! I have some experience working on BMWs. Had a similar situation with my 2017 M3 last year after getting the fuel filter changed. The symptoms you're describing sound really familiar, my car was doing the exact same dance. Took it to my regular workshop and turns out it was just a sensor error that needed to be reset after the fuel filter replacement. They had to clear the error codes and recalibrate the fuel system. Cost me about 45 Euro and fixed everything, no more check engine light, smooth idle, and power was back to normal. Before I jump to conclusions though, could you share some more details? Like: Did you have any recent work done on the fuel system? What's your mileage? Are you getting any specific error codes? If it's what I think it is, it's a pretty straightforward fix. Let me know those details and I can probably point you in the right direction!

Thanks for the detailed response! My M4 is at 40669 KM and just had its service last month. Haven't had any recent work done on the fuel system, but these issues started popping up about a week ago. Unfortunately, I don't have the error codes handy, will need to get those checked. Really appreciate the insight about the sensor error though, gives me hope it might not be something major. Did your car also have that weird hesitation when accelerating? That's what's worrying me the most about mine right now.

Oh yeah, I totally get what you mean about the hesitation! My M3 had that exact same weird lag when accelerating, it was super annoying, especially when trying to merge onto highways. Actually, now that you mention the recent service, I'm wondering if it might be something similar to what I eventually discovered with mine. Initially thought it was the fuel pressure regulator too, but after digging deeper, it turned out to be an issue with the mass airflow sensor. These cars can be pretty sensitive to even slight contamination in the sensor. During my regular service, they must've disturbed some dust or debris that got into it. The hesitation in acceleration, combined with your other symptoms, sounds really similar to my situation. The fix was actually pretty simple, they cleaned the mass airflow sensor and reset the ECU. Total game-changer! Car went back to running smooth as butter. Since you mentioned your service was just last month, might be worth checking if anything got knocked loose or if any sensors need cleaning. These M engines are amazing but can be pretty finicky about their sensors being spotless. Would definitely recommend getting those error codes read though, that'll tell us exactly what we're dealing with. Keep me posted on what you find out!

Thanks so much for sharing your experience! That's super helpful, especially the bit about the mass airflow sensor, I hadn't even considered that could be the culprit. The way you described the hesitation is exactly what I'm experiencing. It's kind of a relief to hear it might be something relatively simple like a sensor issue rather than the fuel pressure regulator I was worried about. I'll definitely get those error codes checked first thing tomorrow. Think I'll mention the mass airflow sensor to my mechanic too, since my symptoms match what you went through. Makes sense that something could've been disturbed during the service last month, the timing definitely lines up. Really appreciate you taking the time to share all this info. I'll update you once I get it checked out. Fingers crossed it's just a sensor cleaning and reset like in your case!