heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Fun stuff arrived in the mail:




I only ordered four parts (one of each), but got duplicates of the smaller ones. I guess the people at sendcutsend saw my insane design and ran a couple through to make sure they were actually manufacturable. Heh.

Chopped off the bend extensions and cleaned up the edges with an angle grinder:





Of course I couldn't help myself and had to test fit on the car as well:






They fit great!

...which I guess isn't hugely surprising cause the CAD said they should. More of a testament to sendcutsend's accuracy.

And here's the latest version of an image you'll be very familiar with if you follow along with this journal:



Dropping the sheet metal brackets off with Tony (TC Design) early next week so that he can weld them up for me. After that, I just need to bond the stock brackets to them. Hopefully that means test drive before the end of next week!

3M never got back to me about whether or not the 07333 will survive powder coating cure temps. Need to bug them again. Finishing is a future problem though, I'm much more excited to see how this thing drives with the bracing

Also, found a BMW plastic plug (51711906001) that fits the 10mm hole in the engine bay harness box where the MAF wiring usually exits:



Quality is honestly way worse than I was expecting for a genuine part. Look at how shitty it looks compared to the plug in front of the DME. It wasn't expensive or anything, but it does kinda look like I just put some electrical tape over the hole.

Oh well, no one is ever gonna be looking at it. Plus, it's essentially hidden with the strut bracing installed.

[heinzboehmer]

Yep, order cancelled because the minimum order quantity is 50m. Damn, I really don't want to have to order that much. Anyone need 49.5m of the stuff?

I might have found a place in the UK that will sell me just 1m of the tubing. Shipping is insane (like $50 for $5 of tubing), but maybe.

Remembered I have a scan of the engine bay with the braces installed, so drew up a super rough layout for the tubing to give me an idea of how much I need. I'll likely bring that big bend in a bunch in the real design, but I wanted an upper limit for length:



Measures right about 480mm, so my 50cm estimate was spot on. Seems like 1m would be enough.

To form it, I plan on 3D printing a jig. Here's a rough idea of what that will look like:



It'll be printed in sections so that I can heat the tubing up with a heat gun (away from the next meltable section) and then form it around the next bend. The ends of the jig will also have tapered flaring sections to make sure the tube can slide over the fittings:



<imaginary pic of heat gun heating up length of tubing sticking out of the jig>



The actual jig will have locating features between all the sections, so that they easily slot together and you don't need to be messing around with it while holding the rapidly cooling tubing. Additionally, it'll have clearance on the outside of all the bends, so you can wrap the tubing around the form (think brake line bender), as opposed to pushing it into a groove.

I'll also be printing a tool that clamps the ends of the tubing onto the fittings, to give it that nice OE look:



Wait a second...

All this brainstorming has made me come up with an excellent way to justify buying 50m of the stuff. Might not even need to jump through hoops to get less!

If someone has the OE CSL part (11617833647) installed and is willing to let me scan their car + the part, I can make a jig to recreate it. All of the designs for the tools (jig + crimp) will be open source, so people could just buy a length of tubing from me, print the tools and make themselves a replica part for their regular airbox installs. Will sell for material cost + shipping (likely <=$40 all in), so this should be a great way to save $150 and end up with what is essentially an OE part.

I could also form the tubing myself before shipping for some beer money. Buyers would then just need to heat up the fitting ends and crimp them on with the 3D printed tools.

I bet this will pique the interest of at least George Hill and kaiv!

Edit: I guess I could also recreate the tube for the stock intake, but not sure the market is big enough to justify the engineering time for that version.

[bavarian3]

Also, quick side project to give myself a break from all the CAD work.

I've never been fully satisfied with the Kassel MAP sensor solution. It being so close to the throttle bodies means that the sensor sees huge fluctuations in readings with each revolution of the engine. This doesn't seem to affect drivability much, but it's never sat well with me. Additionally, the harness going to the sensor has to make some very sharp bends to make sure it's out of the way of the throttle linkage. Again, not something that affects how the car drives, but I didn't like it.

A week or so back, I noticed the CSL air rail was ~$400 after tax on ECS (and in stock in the US!), but closer to $800 through european sellers. NLA fear creeped in sooo I jumped on it:

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250707_185556.jpg","data-attachmentid":311626}[/ATTAH]
[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250707_185611.jpg","data-attachmentid":311627}[/ATTAH]

My original plan was to just kinda re-zip tie the harness I had made for the Kassel sensor and call it good. However, I found sketchy patchwork in the middle of the IAT harness that I had forgotten about and this ridiculous choice by Kassel for the MAP sensor connector (on the left):



For some reason, they used the wrong terminals, put no waterproofing grommets in there and picked a questionable wire gauge for one of the three wires. The connector housing is also clearly a knockoff with pretty bad tolerances. I would not be surprised at all if this is the cause for my intermittent MAP sensor code (which, admittedly, never seemed to affect how the car ran).

The stuff I laid out to the right are the closest replacements I could find in the stash. I rewired that part of the harness with those, but I've ordered the correct terminals and grommets and will replace soon.

I was already halfway into building a completely new harness, so I decided to just redo the entire thing. This is how I routed everything:

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250707_213113.jpg","data-attachmentid":311629}[/ATTCH]
[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250707_213921.jpg","data-attachmentid":311630}[/ATTAH]
[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250707_214255.jpg","data-attachmentid":311631}[/ATTAH]
[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"original_a24f94e3-6abd-428b-9cd0-0cd3f83b7ab4_20250707_215246.jpg","data-attachmentid":311637}[/ATTAH]
[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250707_222412.jpg","data-attachmentid":311632}[/ATACH]
[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250707_222458.jpg","data-attachmentid":311633}[/ATTCH]

As you can see, I ran my sub-harness directly into the bottom of the stock engine harness box thing by the brake booster. Not having that extra conduit snaking down the front of the harness box cleans up the engine bay nicely:

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250707_235153.jpg","data-attachmentid":311634}[/ATTCH]

I did briefly consider running the wires through the stock conduit that runs under the airbox and then making a slot (with a matching 3D printed grommet) in the hard plastic distribution block bolted to the engine for the IAT + MAP sub-harnesses, but ultimately decided that was way too far down the rabbit hole. I'll revisit and do it that way if I ever run out of projects

I, unfortunately, did not have the appropriate terminals for the IAT, so I left some slack in the harness and ordered some of those as well. Slack is tucked into the conduit for now, but I'll be swapping things when I get the parts. Getting the boots over the conduit is gonna be a fun adventure:

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250707_235516.jpg","data-attachmentid":311635}[/ATACH]

(yes, I also ordered a new boot for the IAT)

Anyway, next up I printed karter16's Bosch MAP adapter out of PET-CF, for it's temp resistance. This filament has a heat deflection temperature of 205 C, so should work well for the application. Also grabbed the complementary hardware:

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250708_191235.jpg","data-attachmentid":311636}[/ATACH]

Just like karter16 noted, the metal sleeve on the Bosch MAP just barely doesn't line up with the air rail. Dremel + a carbide bit made quick work of this though:

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250708_192920.jpg","data-attachmentid":311638}[/ATTCH]

Gave the sensor and adapter a quick scuff, then bonded them together with some CA glue. This part isn't really necessary, but I did it anyway cause why not.

Here's the final install:

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20250708_205750.jpg","data-attachmentid":311639}[/ATACH]

(yes, I know that's a 90 deg boot, straight one is in the mail)

The screws did start digging into the plastic on install, so they got torqued to "as much as I can turn just the bit with my fingers". I don't think this is gonna be an issue.

Datalogger is picking up readings from both sensors just like before, so I'm calling this a success. Huge thanks to karter16 for sharing the adapter and all the details surrounding it! Made my life so much easier.

You're on it! That was fast. Super helpful for me as I'm collecting parts. One more DM incoming =)

[heinzboehmer]

Placed an order with one place whose website allowed me to order 5m, but we'll have to see if they actually fulfill my order

Yep, order cancelled because the minimum order quantity is 50m. Damn, I really don't want to have to order that much. Anyone need 49.5m of the stuff?

[heinzboehmer]

Oh! Parts arrived for another project that I can work on if I need a break from the braces CAD (with, uh, more CAD...).



Found these when driving my in-laws' Mercedes SUV (GLB/C/E/something or other). Collapsible baskets aren't exactly a revolutionary invention, but this is a Mercedes OE part (p/n A2038400020) and it's only $16 brand new!

Here it is unfolded, M1 16" MacBook Pro for scale:



Plan is to design some mounts that the basket can clip into. Underside has a ton of features that I can use both for locating and retaining:



Mounts will likely get attached to the "ceiling" of the trunk (where the stock subs live), maybe even the trunk lid, we'll see.

I do want to make the mounts fairly platform agnostic. Each car is getting its own basket, so want to minimize the extra work required to make these compatible with each chassis.

[heinzboehmer]

Datalogger is picking up readings from both sensors just like before, so I'm calling this a success.

Success indeed! Test drive went great. New MAP location + non-shitty wiring seems to have cleaned up any remaining low RPM weirdness, awesome.

Extremely happy with how the car is running now, especially with all the recent cold start updates to the mullet tune!

[Obioban]

Hmm, not sure I follow.

The screws go through the adapter and engage the threads on the air rail. Don't think heatserts would have helped here.

Oh right, herpity derpity. Ignore me.

[heinzboehmer]

You can use heatserts with PET-CF

Hmm, not sure I follow.

The screws go through the adapter and engage the threads on the air rail. Don't think heatserts would have helped here.

[Obioban]

You can use heatserts with PET-CF

[heinzboehmer]

Also, quick side project to give myself a break from all the CAD work.

I've never been fully satisfied with the Kassel MAP sensor solution. It being so close to the throttle bodies means that the sensor sees huge fluctuations in readings with each revolution of the engine. This doesn't seem to affect drivability much, but it's never sat well with me. Additionally, the harness going to the sensor has to make some very sharp bends to make sure it's out of the way of the throttle linkage. Again, not something that affects how the car drives, but I didn't like it.

A week or so back, I noticed the CSL air rail was ~$400 after tax on ECS (and in stock in the US!), but closer to $800 through european sellers. NLA fear creeped in sooo I jumped on it:




My original plan was to just kinda re-zip tie the harness I had made for the Kassel sensor and call it good. However, I found sketchy patchwork in the middle of the IAT harness that I had forgotten about and this ridiculous choice by Kassel for the MAP sensor connector (on the left):



For some reason, they used the wrong terminals, put no waterproofing grommets in there and picked a questionable wire gauge for one of the three wires. The connector housing is also clearly a knockoff with pretty bad tolerances. I would not be surprised at all if this is the cause for my intermittent MAP sensor code (which, admittedly, never seemed to affect how the car ran).

The stuff I laid out to the right are the closest replacements I could find in the stash. I rewired that part of the harness with those, but I've ordered the correct terminals and grommets and will replace soon.

I was already halfway into building a completely new harness, so I decided to just redo the entire thing. This is how I routed everything:








As you can see, I ran my sub-harness directly into the bottom of the stock engine harness box thing by the brake booster. Not having that extra conduit snaking down the front of the harness box cleans up the engine bay nicely:



I did briefly consider running the wires through the stock conduit that runs under the airbox and then making a slot (with a matching 3D printed grommet) in the hard plastic distribution block bolted to the engine for the IAT + MAP sub-harnesses, but ultimately decided that was way too far down the rabbit hole. I'll revisit and do it that way if I ever run out of projects

I, unfortunately, did not have the appropriate terminals for the IAT, so I left some slack in the harness and ordered some of those as well. Slack is tucked into the conduit for now, but I'll be swapping things when I get the parts. Getting the boots over the conduit is gonna be a fun adventure:



(yes, I also ordered a new boot for the IAT)

Anyway, next up I printed karter16's Bosch MAP adapter out of PET-CF, for it's temp resistance. This filament has a heat deflection temperature of 205 C, so should work well for the application. Also grabbed the complementary hardware:



Just like karter16 noted, the metal sleeve on the Bosch MAP just barely doesn't line up with the air rail. Dremel + a carbide bit made quick work of this though:



Gave the sensor and adapter a quick scuff, then bonded them together with some CA glue. This part isn't really necessary, but I did it anyway cause why not.

Here's the final install:



(yes, I know that's a 90 deg boot, straight one is in the mail)

The screws did start digging into the plastic on install, so they got torqued to "as much as I can turn just the bit with my fingers". I don't think this is gonna be an issue.

Datalogger is picking up readings from both sensors just like before, so I'm calling this a success. Huge thanks to karter16 for sharing the adapter and all the details surrounding it! Made my life so much easier.

[heinzboehmer]

This is frickin cool

Thanks! More to come soon.

Small update for now. I think I've found a suitable replacement for the tubing that BMW uses on the brake booster shut off valve: Festo 570360 - PAN-MF-10X1,25-SW Plastic Tubing

Conforms to DIN 73378 just like the OE stuff, measures the same and looks the same. Only issue I'm running into is that basically no place wants to sell me the tubing in lengths smaller than 50m. I only need like 50cm of the stuff, so it would be a huge waste of material and money to buy that much. Placed an order with one place whose website allowed me to order 5m, but we'll have to see if they actually fulfill my order.

The flexible vacuum hose I have on there now works fine, but its OD is much larger than the OE stuff and it rests on the E86 braces, as seen here:

And this one gives a good sense of how tight the clearances are:

The Festo stuff should be a much better fit for this application, as I can bend it out of the way and make sure it doesn't contact the braces.

[siamkazi]

This is frickin cool

[0-60motorsports]

Today I started on the painful process of recreating the stock plastics in CAD:



This is gonna take a while...

Great work brother!

[heinzboehmer]

Today I started on the painful process of recreating the stock plastics in CAD:



This is gonna take a while...

[heinzboehmer]

Speaking of packaging, I scanned the engine bay with the braces installed and then individually scanned the firewall plug, the cabin air filter housing and the cable tray. Here's how they fit up in CAD:




Interference with the firewall plug is minimal, which is nice. Very little work needed there:



As expected, there's tons of interference with the cabin air filter housing. This one will need significant modifications:




Fortunately, it looks like I can keep the stock cable tray! I was not looking forward to redesigning that part:



Of course, not all good news. Braces interfere significantly with the air filter:



Looks like if I raise the rear by 30mm, it'll clear:



Mocked up what that would look like with some spacers and I might be able to pull it off:




The rear edge doesn't really seal with it propped up and the air flow over it looks like it would be greatly reduced



I don't know if spacing up is the right solution. I need to give this more thought. Might need a more substantial redesign of this interface on the cabin air filter housing.