Curiousity questions: Cabin Air Filters and Hill-Hold Clutch

[Z4Mariner]

I've had my coupe now for over two years and about 22K miles. It's great fun, and for Summer it's my daily driver. I've done a few mods, aimed at modernizing but keeping it looking like it could have been OE. I appreciate the sharing spirit of the members on this board !

I have two questions that I hope some of you can answer:

1) Does the OE BMW Cabin Air Filter (CAF) fit and install more easily than Hengst or other brands ? Which brand CAF installs best ?

I've renewed the CAF on my car twice - once when I got the car, replacing what might have been the original, sorry-looking, BMW branded filter. I replaced it again today, with the second of 2 Hengst filters I purchased at the same time. The BMW filter was out-of-shape from age, so I can't tell exactly how well it fit when new. The well-made Hengst filters are challenging to push all the way home to the top of the enclosure so that I can slide the filter door into place. Watching a YouTube video, others really squeeze and deform the filter getting it into place. Are some filters a better fit, or is that just the way of this job?

2) How Does the Hill-hold Clutch feature on manual transmission LCI cars work ? My car definitely has the feature, though the incline seems to have angle-sensed threshold.

It's been my guess that this is this an electronic control of brake fluid pressure via the ABS, which releases brake pressure only as the clutch is engaged ? Maybe someone can share knowledge from TIS or other source.

Thanks for your thoughts -

 

[1536Z4]

1) Does the OE BMW Cabin Air Filter (CAF) fit and install more easily than Hengst or other brands ? Which brand CAF installs best ?

I recently changed mine to a Mann filter CUK2339 which was much better quality than the one I took out and it fitted quite easily .

 

[Z4Mariner]

Thanks, I'll try them next !

 

[fredej]

My understanding is that Mann is the OE manufacture of the BMW branded CAF. Part number CUK 2339.

Start assist works the way you describe. This links contains a lot of BMW technical documentation that you may find interesting. You can find a short description of Start assist in ST502 05_E90 Dynamic Driving Systems, page 9. (assuming the system on Z4 works similar as E90-generation)
https://archive.org/download/BMWTechnicalTrainingDocuments

For Z4 the documents of interest are;
ST045 for Z4 description, mainly E85 pre-LCI. But most of that still applies to the E86
ST601 for short description of LCI changes
ST613 for N52 engine family

 

[1536Z4]

Thanks, I'll try them next !

Sorry my mistake it was a Mann CUK2339 . Getting my Manns and Mahles mixed up I have edited my first reply .