New to the N54.


New Member
Dec 31, 2023
I just replaced the N54 in my '08 535i. This my first sport car build since the late 80's. What a learning curve!
The motor is awesome, although now I find out my 535 is not the car for a hobbyist.
It is not easy to work on and everything seems even more expensive... 😬
I've been chasing misses that began a while after I was back on the road.
Motor is stock except TDO4's with upgraded inlets. I do have a MHD full package but my issues do not change with the tune even when stock.
My o2 sensors are new and are run correctly, although my codes frequently show they are crossed.
My injectors are 12's with about 2k miles. My issues do not change when I move them around. Same for my new Bosch coils.
The miss will happen right after start up if I don't immediately drive. When they do happen, I can hold the throttle where it's at and it will clear in about 10 seconds and the car runs great. I I accelerate too quickly, it will miss. If I turn the car off and restart everything's fine until next time.
There are no exhaust or vacuum leaks.
I had been driving to and from work at 90 mpg without a hiccup and around town paying attention to my throttle aggressiveness.
Yesterday it ran bad..bad. Among the codes were "throttle jamming" and "throttle jammed". I have cleaned it. I parked the car.
I really am tired of throwing money at it. If I need a throttle body, that's cool, but I'd like someone to look at my graphs.
There are no WOT pulls because my tranny is stock and of an unknown condition. Not something I want to replace at this time.
Very cool site. Be gentle I'm a Newb and thanks in advance for any feedback.
Last edited:


New Member
Apr 4, 2024
If you have cleaned throttle body, the TPS (throttle position sensor) , will require resetting.
Can be performed manually.
Foot off brake and turn key to on position. Press start button twice, without starting.
Apply accelerator pedal to floor.
Hold for 1 minute.
Lift foot off pedal and push start button
Let vehicle sit for 20-30 min.

This may help.

Also ensure you have 98 oct fuel or greater.