[Paxandrax]

I recently added a cold air intake to my 2007 328i e90 and the bracket for the sensor housing on the new intake was broken to where I could see the sensor’s o-ring, I should have put the old air box back on but instead I drove for about 3 days and it was fine, no problems. But on the 4th day I started it in the morning and while at a red light my engine turned off, idk what to think about it so I kept driving cuz I had a lot of errands to do. I it got a lot worse throughout the day and eventually my check engine light came on so I went to Autozone and ran the codes and it said my MAF sensor was the problem. So I bought a new air filter for the original air box and some CRC MAF cleaner, and reinstalled the factory intake. Cleaning didn’t work, so I bought a new MAF. Replaced the MAF today and disconnected the battery for 10 minutes to reset the ECU and ran idle for 20 minutes, but still experiencing problems. Engine chugging, revving by itself while idle and when I press the gas it revs and when it goes to zero rpm’s the engine turns off. I was originally experiencing overheating but as from what I can see it’s not happening as bad anymore. I did notice a liquid coming from exhaust while running idle and a lot of smoke coming from the engine bay which already happened but more than usual now. I have no idea what I’m doing or what could be wrong or what to check for and don’t have money for a mechanic. Any help is greatly appreciated

[bkwld]

I would say make sure the MAF you bought is OEM and the correct part number.

[gbalthrop]

Originally Posted by Paxandrax

I recently added a cold air intake to my 2007 328i e90... I went to Autozone and ran the codes and it said my MAF sensor was the problem.[NO Fault Code says a Sensor is "the problem", it merely indicates if the Sensor SIGNAL is absent or "Out-of-range". To help YOU Diagnose the issue, we need to know ALL DME (Engine Control Module) Fault Codes read: the exact code, whether Hex-code or P-code. It COULD be a wiring or connector issue, rather than the Sensor itself.] So I ... but still experiencing problems. Engine chugging, revving by itself while idle and when I press the gas it revs and when it goes to zero rpm’s the engine turns off.

Welcome to the Forum!
First easy thing to try is simply DIS-Connecting the MAF Sensor connector, and see if engine runs normally. You WILL have warning light (SES) due to MAF being disconnected (NO MAF Signal), but "Mapped Fueling" based on RPM SHOULD occur with improved performance.

Without knowing exactly what you did, working in the area at front & Left of engine may have damaged wiring or connector related to MAF (or other sensors), or you may have a "Vacuum Leak" where air that has NOT been "Measured" by the MAF Sensor is entering the manifold, resulting in Lean Running, rough idle & engine Stall.

Rather than spend/ borrow money for "Part$ Throwing$" by a Shop, for $30 to $35 YOU can get a reliable Diagnostic Tool that Forum Members can help you learn to use. If you've NEVER used a Scan Tool before, to read Fault Codes in the Engine Control Module "Fault Memory", or to View Live Data, YOU can get an entry-level Scan Tool on Amazon in that $30-$35 Price Range.

If you have a Windows Laptop, you can spend the SAME money on a K+DCAN Cable to connect laptop to OBD II Socket and download BMW Factory-Level INPA Diagnostic Software that allows YOU, with Forum Help, to read fault codes in ANY of the nearly 20 Modules of your vehicle. If you have an Android Device/ Phone, you can use something like BimmerGeeks ProTool to do many of the things INPA can do.

So consider this a wakeup call that you NEED to invest a few dollars in DIAGNOSTIC Tools. What if your Starter won't crank, or engine won't fire some morning? Towing plus Diagnostic Fees by $hop would be > Price of new Laptop (currently $200 to $400 for Lenovo Brand on Amazon).

The Forum can HELP you find needed Tools and HELP you diagnose the issue with whatever tools you have. Minimum tool required is Multimeter ($7 HFT, $12 Amazon). We can provide wiring diagrams, component locations and Connector Views that identify WHAT wires & sockets to test, and HOW to test.

It's a "NO-Brainer": You NEED to learn how to at least read P-codes in the DME (Engine Control Module), and how to report that information HERE for guidance on "Next Steps". See attached pdf: "E9x References" for more info on Diagnostic Tools. Entry-Level Scan tool & Multimeter such as the following are ALL you need for this issue:
https://www.amazon.com/Autel-AutoLin...xpY2s9dHJ1ZQ==
https://www.amazon.com/Plusivo-Digit...s%2C157&sr=8-5
George