2001 BMW 325 engine clicking sound

Thanks for donating. The issue you are having will definitely require scanning the car for faults. Have this done and then we can make some sort of determination as to the proper course of action. It is unlikely that my input will be helpful without this being done first because of the complexity of these cars, there is just too much to go wrong to be accurate.

did some troubleshooting today found out that when disconnecting mass air flow system rough engine knocking stops and rough iding not as bad as when the mass air flow is connected. Appears to be the mass air flow should need replacing, could I be missing something.

now that It has been confirmed tentatively I think i need a new mass air flow...My bmw dealer has quoted me the 715.00 plus tax. I might as well give them the car. Looking online I have seen half that cost and have even seen MPG AUTO PARTS ON EBAY listed at 60.00 dollars. Please help is online in your opinion too much of a risk with a Mass Air Flow. If not is there a place you would recommend in buying this part. I just know there is no way I am dishing out 715.00

Call my source at Autobahn dismantling, (619)444-2290. John will ship the needed part

Before replacing the maf. I finally got a hold of an obd code reader. Although yesterday got error codes relating to self inflicted(didn't plug cylinder 6 after replacing spark plug) but that's another story. Now that everything is in order I did not get the P0101 code instead got P0300(Random or multiple misfires detected and P0313(Misfire detected with low fuel). This does seem to point to the MAF, again when I disconnect the maf it does idle a bit rough which can be expected but not the the rock and roll I get when its connected. Again all signs point to the maf but is there something I could be missing.

I am guessing the code reader is a generic reader, is this correct?

The 3030/0303 Car Reader is capable of retrieving manufacturer specific codes. The tool will retrieve both Generic (P0, P2, P3, and U0) and Manufacturer Specific (P1, P3, and U1) OBD2 DTCs. more information on the product is located at www.Canobd2.com. Maybe I should mention that I did get all sorts of Manufacturers code(such as p1342/p1352/p1353 just to mention a few) when I scanned obd codes but thought they were all related to the generic codes so I didn't mention them because I didn't think it neccessary. But if you want I could rescan and send them to you.

My concern is that the scan will not be capable of reading the specific reason the code was set. The generic scan tool is typically not my tool of choice for pulling codes on these cars. Autologic or the factory scan tool will read the faults and then I can offer advice that is meaningful.