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Discussion Starter · #1 ·
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!
 

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Sounds like you've been throwing a lot of parts at the problem in an attempt to fix it. For a miss and lean condition, first thing to check for is vacuum leaks. Good candidates for this on the E46 engines is the intake boots, area around the intake manifold and vacuum line running around the back of the engine. With that age and presumably > 100K miles, they deteriorate significantly. Not certain about the "hard knocking sound" You can narrow that down to an area using a long screwdriver or stick ( about 18") as a stethoscope. Put one end against your ear (not in it) and the other end on the place you want to hear. Check the timing chain area, the rectangular box on the intake manifold (DISA) and valve cover. You can also use this method to search for a vacuum leak using a hose/tubiing, but it is a bit more difficult.

Another good resource for the older 3 series BMWs is E46fanatics.
 

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Discussion Starter · #3 ·
Sounds like you've been throwing a lot of parts at the problem in an attempt to fix it. For a miss and lean condition, first thing to check for is vacuum leaks. Good candidates for this on the E46 engines is the intake boots, area around the intake manifold and vacuum line running around the back of the engine. With that age and presumably > 100K miles, they deteriorate significantly. Not certain about the "hard knocking sound" You can narrow that down to an area using a long screwdriver or stick ( about 18") as a stethoscope. Put one end against your ear (not in it) and the other end on the place you want to hear. Check the timing chain area, the rectangular box on the intake manifold (DISA) and valve cover. You can also use this method to search for a vacuum leak using a hose/tubiing, but it is a bit more difficult.

Another good resource for the older 3 series BMWs is E46fanatics.
I got my fuel/air adjusted by a mechanic today and it runs better and sounds better but still seems to be a slight tick sound coming from the coil packs. I’m gonna try the screwdriver trick but I check all plugs and coils and they all seem to be tighten and workin well. U think it still running a little lean could cause it to sound off? And I also just bought new ngk spark plugs and bremi coils and boots from autohausaz that I’m gonna install. In ur opinion, are those good brand parts to put in? I know bmw is very precise on the quality parts you install
 
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