heinzboehmer's 2002 Topaz 6MT Coupe

[Bry5on]

Brilliant idea to record the traffic during an INPA session

[heinzboehmer]

Stuck home with a cold this weekend, so I knocked out some boring maintenance that I had been putting off for a couple months.



Swapped fuel filter, filter to fuel rail line, EGT, PCV line that goes to the airbox and a bunch of underside trim clips/screws that were starting to get old and worn. Always fun to do your best to evacuate the system of fuel beforehand, only to still have it spill everywhere.

Everything else was uneventful. I haven't seen the intermittent EGT code I was getting pop back up and EGT readings on Gauge.S are different now. I say "different" and not "correct" because it's clear the scaling is still way off.

Originally, I was planning on using this new sensor to calibrate the Gauge.S reading. DME has this table for the sensor:



And a third degree polynomial fits it perfectly:



So, it should just be a matter of exposing the sensor to a few known temps and measuring its output to correlate it with the graph.

I was about to head to the kitchen for some ice water when I realized that the DME is likely not sending out the raw sensor values over D bus. All other temp sensors are scaled linearly in the output data, so it would be very unlikely that this one is different. I'll check to see if INPA or DIS show EGT. If they do, it should be super easy to figure this out using a technique like this one: https://github.com/tomicooler/bmwe46...il-temperature

I did also set up the cheap logic analyzer I got and started trying to figure out why the V5 Gauge.S doesn't work with the DME, but the V4 does. Here's version 1 and 2 of my D bus probing setup:




I haven't really gotten anywhere yet. The V5 board on older firmware was sending out the correct DS2 commands, but would then hold D bus low and not allow the DME to respond. Updated the firmware and swapped the janky trimpot I had used as a D bus pullup for a properly sized 10K ohm resistor, then tested again.

Janky:



Not janky:



Now Gauge.S sends out the correct command and the DME responds with a valid response, but for some reason the device still does not display anything. It communicates just fine with the MK60, so I'm fairly convinced this is a FW issue. Unfortunately, Gauge.S FW is closed source, so I can't really debug this...

Anyway, I'll keep messing with this and update with any resolutions.

[heinzboehmer]

Small addendum to the phone holder project. Drove the car a bunch last week and found two issues with the bumpers that hold the phone in place:

• Top bumper is designed to be a press fit into the top tab. The top tab has a rib in it for rigidity, but because of packaging reasons, it had to face down. This means when the tab + bumper are pressing against the phone, the bumper is also being forced forward. After enough vibration/time/etc. the bumper will fall off. Was fun trying to catch my phone lol. Some visual references of the design:

One good solution would be to add a ledge to the end of the tab that will hook into the bumper once installed. However, this would leave overhangs inside the bumper and I really didn't feel like spending a bunch of time trying to print an overhang without support using that super soft stuff. So, a dab of 3M emblem and trim adhesive was the solution I picked.

• Turns out the super soft filament was too soft for the bottom bumper. Again, after enough vibration cycles, the phone would scoot forward just enough and bend the bumper out of the way. Was also fun to try and catch it when this happened. To fix, I extended the bumper forward by 2mm (to cradle the phone a bit better) and printed it out of the harder TPU. This bottom piece is really just acting as a rest for the phone, so the hardness of the material doesn't really make much of a difference with how well it's held in place.

Besides that, holder has been great! Pretty happy with how it turned out.

[heinzboehmer]

Annual wheel bolt replacement came a bit early cause I noticed some slight surface rust on some of the rear bolts. It's very orange (i.e. newer), so likely just from heat cycling at the track and getting washed.



The ease with which I can replace these is the number one reason why I don't have a stud conversion kit installed

[heinzboehmer]

If no one else tells you this let me, this development of the vent phone mount has been awesome! Also if you ever feel bothered to print another I would love to buy one

Thanks!

Here's the CAD if anyone wants to print it out: https://cad.onshape.com/documents/aa...abcccfec208abd

Anything suffixed with "Bumper" is made to be printed out of a flexible material (regular 95Aish TPU works, but the super soft 60A stuff works better) and everything else is made to be printed out of ABS or similar.