06 530i 109k
Just changed my plugs with OEM NGKs, also did the valve cover gasket. As soon as I started it up, the RPMS go up to about 1100, then drop down pretty low to 300, then act normal. this never happened prior to changing the plugs and gasket.

now i have a SES shooting out p0174 and p0171 for system bank too lean. does my ECM need to be reflashed in order to adjust to the new spark plugs? perhaps i over-tightened the plugs themselves? any ideas??

 

doesnt really sound like a plug issue to me.
did you accidentaly leave any sensors unplugged?
did you start the car with the intake pipe off?

 

I think that you forgot to plug something in. Sounds like you may have a vacuum leak possibly. What sensors did you unplug and are they plugged back in? I could be your oil sepator. Obviously you changed the oil upon doing a gasket change, do you have the correct amount of oil in the vehicle right now and did you mess with the vanos unit?
This does not sound like a plug issue to me. Check to make sure all of your coils are seated properly and plugged in properly

 

First, I really appreciate the help (these were my first DIY, ever). the coils were put back correctly, as was the valvetronic motor with its new gasket. the valvecover gasket screws that i purchased from the dealer are not aluminum, because they said they stopped using them in N52 motors. I didnt take the fuel line off, but i did push it back some.


I know that broke the place piece that holds this plug, but none of the pins were broken. i couldn't find the name, but it is located on the valve cover under where it says t6151 in this figure (it has a spherical shape)

again, i didn't break any pins, and it is plugged in, but the way it "locks" into place has been affected.




only other thing i unplugged was:

intake/exhaust camshaft sensors (2 wires look identical, front of engine)


^^^maybe those were put back in the wrong place?

 

i changed it with 6.9 quarts of oil, and i did not start the car with the intake pipe off.

 

Ok, you removed the valvetronic motor. I'm guessing maybe something happened there. That part controls the idle from what a tech told me.
Was there only one way it goes on?

 

vacuum leak. recheck anything with a gasket or seal.

 

the valvetronic motor only goes in one way, as does its gasket and plug. no leaks, no broken hoses.


the abnormal rpm issue happened right after i put everything together, dealer said it takes time for the car to adjust because the of the age of the old plugs?


the SES light came on a couple days after, only after i put i bottle of techron. perhaps it was debris that caused the system too lean code?

 

adjust because of the plugs? that dealer is an idiot. did you try clearing the code and driving it? sometimes if you turn the key on with things disconnected, it will set a fault thereby causing the engine to run on default values. double check the intake hose between the airbox and throttle body. also with that kind of mileage, check the intake boot (between airbox and throttle body) for cracks. check all vacuum lines for cracks as well. you may have inadvertently damaged one during disassembly

 

another thing is to check the idle control valve. once you locate it, with the engine running, give it a tap with a hammer. sometimes they stick and cause funky idling