# Misfires after valve cover gasket replacement



## jjowski (Feb 29, 2020)

Hi I have a 2007 bmw 328xi, and I recently changed the valve cover and valve cover gasket. After the job I noticed that the car had a major misfire and after using an OBD scanner I found the following codes.
Cylinder 1 misfire
Cylinder 4 misfire
Mass or volume air flow too low
System too lean in bank 1 and bank 2
I have a strong suspicion that I have a vaccum leak somewhere, I took the valve cover off again and put it back on making sure the gasket wasnt pinched. Does anyone have any idea on what could be my exact issue. Thanks.


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## Zeichen311 (Mar 31, 2011)

All sensors reconnected, especially the MAF sensor? All ignition coil grounds reinstalled properly?


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## jjowski (Feb 29, 2020)

MAF sensor looks good and grounds were reinstalled fine. However i noticed im no longer getting a misfire code, only a code for Mass or volume air flow too low.
It also appears that recently I might be leaking oil onto my exhaust manifold/primary cats.
I just did a valve cover gasket job and its dry around the gasket so im not exactly sure if this is just old oil dripping on the exhaust or if its leaking somewhere else. Im going to take a look underneath the car tomorrow to see if I can get a better look at it.


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## ard (Jul 1, 2009)

Check pins and wIrving between MAF and DME.’

Try disconnecting the MAF and see how it runs with it disconnected.
Report back


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## BabyUnicornTaco (Jan 8, 2018)

Yeah. Check all the electrical connections. How dirty were the connectors? I like to use CRC electrical connection cleaner whenever I disconnect and reconnect a slightly dirty connector. Also sometimes it’s a really simple, overlooked vacuum leak that’s created from a hose or connection. 


Sent from my iPhone using Bimmerfest


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## jjowski (Feb 29, 2020)

Its been a while but I ended up bringing the car to the shop. The valve cover I had purchased was apparently faulty and had tiny cracks in it causing a vaccum leak. I learned my lesson from buying cheap aftermarket parts. The job is all done now, thanks for the help.


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