I have a 02 bmw 325i and I started out having misfires and running lean codes well I replaced spark plugs and coil packs and didn’t fix it.. too to a bmw mechanic and he replaced the thermostat and it fixed it well all but the running lean problem. I bought a new mass air flow sensor and it didn’t fix it. Well the mechanic said the mass air flow wasn’t any good so I bought a bremi mass air flow which arrived today. I haven’t yet installed but I’ve been running it without the mass air flow hooked up. But since I’ve been having these problems I’ve gotten a hard knocking sound coming from around the engine bay.. I thought it was a loose spark plug at first but I tighten them all down and it still hasn’t fixed it. I’m currently waiting for a overflow tank to arrive to replace the one on it because it’s leaking but I wanna know what to do from there about the knocking ticking sound. It’s not coming from diss Valve the coil packs and spark plugs are new but I’m gonna replace all of them again. Could it be from not having a mass air flow hooked up? Or you think I just need better coil packs and spark plugs because I installed Bosch coils and ngk spark plugs but it was from eBay so it possibly could be bunk lol that’s why I bought all new stuff from autohausaz. If these parts don’t fix it I guess I’m gonna have to take it to shop to smoke for vaccum leak but has anyone had similar situation and figured out and able to fix the noise cause it really brings down the smoothness of the car lol pleaseeee help a noob bmw owner thank you!