Quote:
Originally Posted by kneedeep
VERY happy to hear that! I swear my 135i didn't sound like that, but i feel better thanks.
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Think I can explain this one.
Your 135i had the N54 engine and this featured Piezoelectric injectors, which are very efficient and quiet.
The Z4 has the N55 engine and this features Solenoid injectors, which upon inspection aren't as efficient as the Piezoelectric ones. However, I think they lend themselves to more customisation and variability in the spray so they may work out better. Anyway, simply put, the Solenoid injectors are louder than the Piezoelectric ones, hence the more pronounced direct injection ticking noises we are hearing from the N55 35i and N20 28i.