I've been into n54's for quite some time when I was first impressed by the immense amount of power they are capable of producing with so few mods. I bought my 535i in 2011, but didn't really get into tuning it much.
However, a few months ago I picked up an e90 335i which is now my tuning n54. I intend to post updates on this thread about my experiences, troubles, and outcomes of my continued n54 tuning.
About 2 months ago I installed a JB4 G5 ISO and DCI's. At the time I had 76,500 miles with fairly old ignition coils and spark plugs. After installing the JB4 I immediately started getting Cylinder 1 misfires at WOT and anything above 60-70% throttle.
The common causes of misfires on the n54 are spark plugs, ignition coils, and faulty fuel injectors.
I started by replacing the spark plugs which solved my misfire issues. However, my car then developed a rough idle with the new plugs. My guesses for the rough idle were coils, injectors, or dirty intake valves.
Now I'm getting some more misfires at WOT but only occasionally. I swapped my coils on the 535i with the 335i which solved my rough idle issues, so I've probably got some coils that are beginning to fail.
As of a couple weeks ago I started running a mix of E85 and 93 octane - I started with a ~25% mix of E85 which went smoothly, so on my last fill up I went with a 35% mix.
All I'm running is Map 5 with DCI's and E85 and my fuel trims are still looking good even with 35% E85, so I will likely try 40-45% on my next fill up.
This first post is just an overview of my current modding status and future plans, so in my next posts I will go more in depth about specifics like running e85, meth, etc.
The mods I have planned for the next few months include:
-Walbro 255 Inline Pump
-E85 back end flash
-Alpina Tranny Flash
And then some cosmetics:
-CF front lip
-Gloss black or CF grills
-Smoked side markers
-LED license plate light
-Shadowline window trim
Of course, the engine mods are my priority.
I'm very excited to get this Inline Pump and back end e85 flash loaded so I can start running 60%+ E85 and making way more power. I'll keep everyone updated once I start running higher concentrations of E85!