BMW Z4 Rough Idle and Stalling, Fuel Injector Failure?

Hey there! I faced similar issues with my 2008 BMW Z3 last year. Your symptoms sound exactly like what I experienced, rough idle, hard starts, and terrible fuel economy. Had mine diagnosed and it was indeed dirty fuel injectors. The carbon deposits were pretty bad, causing irregular fuel spray patterns. In my case, two injectors were severely clogged and needed replacement, while the others just needed a thorough cleaning. The whole injector situation isn't just a minor annoyance, it can lead to serious engine damage if left unchecked. When my injectors were acting up, it actually caused misfires that could've damaged my catalytic converter. The fix wasn't just a simple cleaning job for me, they had to remove the injectors, test the spray patterns, and do ultrasonic cleaning. The replacement injectors had to be coded to the ECU too. Your diagnosis sounds spot on. With those symptoms and the failed emissions test, dirty or faulty injectors are likely your culprit.

Thanks for sharing your experience! I'm kind of relieved to hear someone else went through the same thing. The symptoms match up exactly with what I'm dealing with now. Do you remember roughly how much you ended up paying for the whole job? Also, has everything been running smoothly since the repair, or have you noticed any other issues pop up? I want to make sure I'm prepared for what I might be facing cost-wise, and it'd be great to know if this fix actually solved everything in the long run. Really appreciate your help with this!

Hey again! Happy to give you an update! Since getting my injectors sorted out, my Z3's been running like a dream. The total bill came to 515 € for fixing the dirty injection valve, and honestly, it was worth every penny. The mechanic found one injector was completely shot, so they had to replace that and clean the others. The difference is like night and day. No more rough starts in the morning, engine runs super smooth, and my fuel economy is back to normal. Best part? Haven't had a single issue since the repair, and it's been about 8 months now. The engine's got its power back, and she purrs like she's supposed to. Just a heads up though, make sure whoever works on it knows their BMWs. The coding part for the new injector was crucial, and not every shop has the right equipment for that. Worth noting that regular fuel system cleaning could've prevented this whole mess, definitely learned my lesson there! Let me know how it goes with yours. Always happy to share more details if you need them!

Thanks so much for all the details! After your advice, I bit the bullet and took my Z4 to a BMW specialist last week. You were absolutely right, turned out two injectors were completely clogged, and one was failing. Cost me a bit more than yours at around 700 for the whole job, but wow, what a difference! Had to laugh because the mechanic said exactly what you mentioned about preventive maintenance. Got a proper lecture about regular fuel system cleaning. My car's running incredibly smooth now, no more stalling, the idle's perfect, and the engine's got its punch back. Even my fuel consumption has dropped back to normal. Really glad I reached out here. Your experience helped me avoid wasting time with unusual fixes, and I knew exactly what to expect at the shop. Think I've found my new regular mechanic too, they really knew their stuff with these cars. Thanks again for all your help! Time to set a reminder for that regular fuel system cleaning...