Jb+ for N55

[zz135i]

I'm leasing a 2012 135i and want to know everyone's opinion on tuning. Since I'm leasing is it even worth trying to tune? (with a JB+) Wasn't sure if the dealer would be able to tell if its been tuned and would void my warranty.

Thoughts?

[abirmaher]

I'm also very curious about this... also what exactly does it change for the car, other than the obvious performance enhancements?

[jzmundy]

Let me just preface this by saying I am unaware of any "tricks" that may be coded into the N55 engine management software (hidden tuner codes, etc.).

However, these "plug-n-play" tunes like the JB+ (or older SSTT), plug into the N55's MAF (mass air flow) sensor or N54's TMAP sensor. They intercept the signal as seen by the ECU and "trick" the ECU into running a higher boost (~4-4.5ish psi IIRC). I'm not sure of the exact "method" by which they accomplish this (some suggest a sort of altitude correction - tricking the ECU into thinking it's running at a higher altitude = thinner air = keep the wastegates closed for a different period of time to build same amount of boost as at lower altitudes).

The beauty of these tunes is that they are EXTREMELY easy to take in/out for dealer visits (HIGHLY recommended to keep your warranty) and they generally run conservative boost levels compared to the more "complete" ECU tunes (PROCEDE, JB4, Cobb, etc.).

However, they aren't able to control/oversee as many parameters as the ECU tunes and thus, are seen by some as being inferior or harmful. IMHO, at the boost levels you'll see with one of these plug-n-play tunes, you won't see any major detrimental mechanical issues (maybe decreased MPG due to a "heavier" right foot haha).

FWIW, I ran a JB+ in my N54 335 for 15k miles with no issues whatsoever (including HPFP issues).

Hope this helps!