Ya, appreciate you chiming in, I figured it's somewhat common. I know boost control is never this perfect steady thing where boost stays exactly at some level.. which is why I'm probably playing with fire and should be focusing on other things. A little spike up and settling down wouldn't bother me if I had a built motor, but I can't set boost cut to say 16 psi, because any accidental spike up might be rod bending time. Boost runnning strictly on wastegate run ~7psi upto 5500ish, and creeps to ~9psi by redline. Car feels good and I don't plan on building a motor anytime soon.

 

I don't know if BMM has the setting, but on Link there's a programmable "dashpot" function to keep the RPM from drooping when returning to idle. It basically holds the IACV open a little extra when returning to idle before lowering to the IACV value in the idle table. I have noticed that it causes the RPM to hang a little when putting around in parking lots, but I haven't fine tuned it and it's not a big deal.

I used to have pretty excessive AE settings because it didn't seem to hurt anything. Eventually I took the car out and slowly pulled fuel, stabbed the throttle and saw how the car reacted. I'd just pull fuel until the car starts hesitating on tip in and then add some back in.

 

There's dashpot on MS based ECUs too. I never liked it much, usually left it around 1%, and used the initial value table to get idle to return to idle correctly. That's only a 5x5 table, I set the left ~100rpm under my hot idle, the right is my cold idle. The rows tend to be set too cold in most base maps, like 0,30,60,110,140, etc. Seems to need only 2 rows for "cold" temps, like 50 and 140, then use the rest for just below thermostat, thermostat temp, and one above, like what you'd be running at on a really hot summer day in traffic. Idle duty requirements usually go down as engine temp goes up, but around 190-205, I find I need a little extra, or it'll stall out or dip a lot when heat soaked.

@SimBa my Link dashpot settings are 1/1/1, so 1% added for 1 second, then decays to 0% over 1 second. Your latest you attached has 3/.4/.7, so you're using a bit more, but not even holding it for half a second, then it goes to 0% in ~3/4 of a second.

 

@curly I've had similar experience when it's really hot out. I've found that, in a couple parts of my tune, that I focus more on the range of "operating temps" compared to warm up, because thermostat temp vs 10 degrees over thermostat temp is usually pretty different conditions.

IIRC when I last played with the dashpot settings I lowered the hold time because it felt like the RPMs were hanging when I was putting around parking lots and such like I mentioned previously. The settings I have seem to work pretty well, but it's been cold and I assume that in really hot and heat soaked conditions it might dip a bit. Next time I give it a look I'll try out your settings. I do have your tune on my laptop and like to reference it as a sanity check.

 

So where did I leave off, I can't remember.. It's been a busy couple months for me between work and other stuff so the Miata took a backseat. Good news, finally got her back together with the new diff in and 6 spd. So backing up a bit..

Stopped by Dave's shop for him to finish up the diff welding. He was nice and let me try out TIG welding on a flat strip of Al. It was fun and TIG is obviously much more controlled and detailed than MIG which is cool. I bought a new HF auto darkening helmet as my friend's solar powered one is crap and I realize now it wasn't working properly and flashed me a couple times. The new helmet is a joy and works properly. Only problem is that I'm reaching old man age and didn't bring my reading glasses. The comfortable working distance was right where the puddle was blurry, so it was a bit of a struggle to see if I had a good puddle or not. Anyway, he welded it up and hopefully it'll be good to go. The old cast Al welded like s**t but it should be good enough.


I need to redo the exhaust on my Honda. I thought about bringing it to an exhaust shop to have it done but what's the fun in that? I like to learn new skills and a new toy would be nice. With the upcoming tariffs I figured what the hell and pulled the trigger. It may not be till winter till I get around to the project but I'm looking fwd to some TIG welding. Picked up an alphatig 203xi.



So with the diff welded, I replaced the bushings and axle seals. I don't have a shop press and they last ones came out pretty easy w/ an air hammer.. Well.. this wasn't last time. The diff had a lot more corrosion on it compared to my miata, and the bushings were a b**ch to remove w/ an air hammer but ultimately got er done.




To swap the diff on the 4 post I had to have the rear up on jackstands on the lift which was kinda funny. For the tranny it was pretty straightforward. I cleaned it up, cleaned up the input shaft and surface for the throwout bearing, swapped over my throwout bearing (since it's basically new), and relubed things. I replaced the rear seal for the driveshaft and used a shifter rebuild kit to replace the little parts for the shifter. One thing a friend recommended was using a jack on top of a toolbox in place of a tranny jack. I tried it for a minute but ultiamtely it was a pita and I thought I could just muscle it. I was supposed to have a 2nd set of hands but schedules change so I just did it myself. I used a toolbox below to initially set the tranny on when removing it. And when reinstalling the tranny, I lifted it onto the toolbox, then put it on my shoulder and got it into place (squats are important). A block of wood under the pan is critical to keep the engine from tilting up and down and allow you to align the input shaft on reinstallation.



Happy to see the rear main seal I replaced isn't leaking. There's a tiny leak up top somewhere, likely the valve cover.



Got the tranny back in place, was reassembling things and found this.. *F**K! I definitely didn't notice the broken bolt for the clutch slave cylinder until it was in place. The space is way too tight so had to pull it again.. Just typical. Never can just do something once.. lol



Fortunately on removal the broken bolt was pretty easy to remove. I cut a slot in it w/ a dremel and it came out w/o much issue. The 2nd time reinstalling the tranny it went much faster and easier. Same method as before.



Put it all back together, added fluids, and took it for a spin. Initial impressions are that the 6 spd isn't too bad putzing around.. we'll see how it feels over time and on track. I can see how 4th/6th can take a little getting used to and finding gears is a *little* more effort than the 5spd. It took me a cpl tries initially to get 6th, but just need to get a feel for it. Tranny fluid is Ford unicorn tears so hopefully that helps with shift engagement but I didn't take it for a long drive. I'm glad I went with a 3.6.. even if a 3.9 might be faster it's just too much shifting imo. Also, it's nice to have a closed diff! I can feel it working and putting down the power as opposed to spinning the inside wheel which is great! I will reiterate my one complaint about the Miata lacking a tranny mount. You get more drivetrain/transmission movement than in other cars with a proper transmission mount. It's not BAD, but noticeable after driving the Honda lately.

I need to check and adjust the ride height a bit to get it exactly back to where it was. I stiffened up the Xidas a couple turns and it's pretty good for the street. You can definitely feel the increased spring rates over the old BCs. Also I need to go over the tune again for the BMM ecu. It could be better in some areas but drives well overall. The 9LR street **** is sitting in a box and need to install that as well. It's a fun little car. I need to sign up for a track weekend now!

 

Nice progress! That's a lot of changes/upgrades at once, even leaving out the upcoming wing install.

I agree about needing a trackday soon. Those wheels and tires don't have enough clag and brake dust on them

 

Ya, I washed the car good this spring, it's all shiny. lol

Drove the car a bit and happy to say it feels good. No complaints about the 6 speed and 3.6 diff so far putzing around the street. Having a lower cruising rpm on the highway over the 5 speed and 4.3 diff is nice too. Also, nice to have a closed diff! The car hooks nicely now in all gears and when powering out of turns! I'm excited to get back on track and just being able to hammer down now. I imagine it has to be worth a good amount of time now with a proper diff.

I had a little annoying idle droop where it would sometimes dip too far below target rpm. Fortunately got some input on the BMM discord and got it sorted pretty easily. I initially thought it was just a little lean down there in the map, but it turns out I just needed to raise the P value (for the PID controller) for the closed loop idle operation. The P value is what makes quick adjustments but too large a value will result in idle oscillation or "hunting." Now it "catches" the dip pretty quickly and I think it might dip down to ~750 (with a target of 880) at times which isn't bad at all. I also spent some time going over the tune again and been making little tweaks to the throttle tip in adjustment and map. I'm definitely a fan of the BMM ECU and more importantly the support and members in the community. I'm guessing the megasquirt has a big community as well, but I'm happy to say you can usually find what you're looking for or some assistance in the discord, which is really nice.

Been ironing out little issues (like mentioned above with the tune) and quite happy with how the car sits currently. I need to sign up for a weekend on track.

 

So weather's been nice this May (unusually a little cool so been putting around with the Miata on occasion). I'm happy to say car feels good. After a few drives I'm adjusted to the 6 speed and don't have an issue with it. I know on track is often different so we'll see how that goes but for fun drives on the street I have no complaint with it thus far. I think the 6 spd being worse than the 5 spd are overblown. Taller FD is definitely nice for highway cruising. Took it to a local cars and coffee with a friend, and he drove his lifted Miata (this is one of his 3 miatias).



Also knocked out a couple more things on the list I wanted to do. The engine ground strap on the back of the engine is kind of old and crusty. I'm not sure if it makes any real difference but I have plenty of spare pieces of wire in the garage so made a new nice ground strap. Can't hurt. Made it out of 4 gauge. I have one of those anvil style lug crimpers you smack w/ a hammer, and it's great for making cables.



The other thing I've been meaning to install is the 9LR street ****. I've been sorta delaying it since I knew I had to remove the little hardtop lip spoiiler, and I knew the seal was damaged underneath at one part. I finally mustered up the desire to fix it and get it done. With the little lip spoiler removed you can see the damaged seal. Ideally I would've bought another piece of the seal to replace it but I didn't wanna screw with this thing for days and look for the right sized seal. So.. I opted for some black RTV and electrical tape. Honestly it came out better than I thought. I had to ghetto rig and weigh the seal down w/ a block of wood so it would set without sticking up but it worked. I had black RTV and electrical tape so that's what I used. From a distance you don't really notice it unless you look for it. The missing seal was filled with RTV so I'm sure it won't leak.




After that was done, onto the wing install. Don't have too much to comment on regarding the 9LR street **** install. I used a tiny bit of black rtv to hold the gurney flap more securely in the channel (to avoid any possible rattling). After drilling the holes I primered the front and back sides of the holes. I find what's easiest is to use spray paint and a cheap disposable chip brush. I had to cut the edges of the trunk lid which is a bit tedious but not hard. I had to take about an 1/8" off from each side. After removing enough material, I masked it off with blue tape and used another chip brush and primer to coat the cut edges. It came out decently. I was a little surprised when tightening down the 1/2" bolts and nuts how much tension they are under. Definitely bends the sheetmetal a bit but not a big deal. For the NB you don't use the provided spacers/templates they give you. Being chassis mounted the wing is very secure.







I chose the 9LR street **** because it's functional and not too obnoxious looking. The car was much more subtle w/o the wing but is what it is. Should I decide to do full aero at some point it uses the same mounting points as the "big ****" so it'll be an easy switch. Only other downside is it will make loading things into the trunk for track days more interesting.. I need a tow vehicle..



Plan is to do a weekend on track June 21st weekend. There have been a lot of changes and I'm hoping to do less wrenching and more driving going forward. I am going to give serious thought regarding buying an AIM or Garmin. It seems like the Garmin is good for the less serious track go-er that wants more immediate feedback whereas a proper aim setup you have to setup a workflow of puling the logs, screens for analyzing them, etc. That's a whole nother can of worms I need to delve into at some point. I'm also thinking more and more about a tow vehicle and being able to hit more tracks. Anyone ever used Turo for weekend truck rentals? Obviously I'd need to rent a trailer also, buddies seem to do the weekend Uhaul rental as needed. I still need to swap the passenger seat at some point but the OEM seat has its advantages. It fits a booster nicely. Honestly haven't tried a booster in the Recaro PP yet.. My youngest is 5 and she likes rides in the green car.

 

Good stuff man, excited to see how the rig handles its first track day in this configuration!

I haven't used Turo for a tow vehicle rental, but if you're thinking about renting a Uhaul trailer, you could always just rent a half ton truck there as well. A couple of my buddies have done that before.

I was pretty set on getting a Garmin until my buddy let me use his Aim for a couple events. The interface can be intimidating but once you've used it a bit, it seems like much more can be extracted from the data. I thought it was going to be a bit of a PITA but it's actually really fun using all the tools available to analyze your best laps against each other or your friends'. Definitely a little more time consuming, though. I think I've only reviewed my data between sessions at the track a few times. Usually I'll go through it the week after a track event and store my best laps to compare against or study for future events.

 

I priced out renting a truck/trailer from Uhaul and it's ~$650 for a weekend. While not cheap, not hateful either if it's only a few times a year. When you add insurance for another vehicle, property tax (ya we have that on cars here in VA), maintenance, and depreciation the cost delta of just renting isn't terrible. I was looking and Turo might be a little cheaper, but having to go pickup a car somewhere, then driving to pickup a trailer from somewhere else would eat up a serious amount of time and probably not worth the $ savings. Of course now that I'm interested in trucks I was checking out my buddy's F150 and I gotta say they are def nice. Not something I'll drive when I go into the city, but putting around suburbia it wouldn't be much worse than the minivan.

It looks like the AIM is definitely the way to go as the Garmin doesn't allow you to d/l the data off the device (I think). I'll just stick with my phone/extenal gps lap timer for this year and think about the AIM next year.

 

A truck that will tow a race car does not have to be nice enough to be a daily driver.

 

Since the track weekend is still a little ways away I figured I'd finally mess with the passenger seat. The seat/brackets have been sitting in my dining room for a while and I've been trying to clean some things up in the house lately so why not kill 2 birds with one stone.. I should add, I test fitted the booster and it fits inside of the seat so it'll fit the smallest munchkin w/ a booster.

On the topic of seats. This is the driver's side door panel that was cut to accomodate the "wing" on the recaro PP seat. Since I didn't want to look at an ugly gaping hole in the doorpanel, I fitted it with a "custom" duct tape "panel." It's ugly but at some point down the road I'd love to make some kind of plastic cover to fit the cut portion of the panel that's glued in place. I'm not sure how I'd go about designing something to 3d print this spot but that's a project for another day. I did think about switching to some flat door panels that are common I've seen but why ditch a perfectly good OEM door panel (I like it looking oemish still). If someone has suggestions (like maybe I can automagically 3d scan the cutout and pay someone to make me a piece) please chime in.



So back to the passenger seat. It's definitely tight like the driver's seat. It looks like the passenger tunnel may need a light massaging in a spot to give an additional 1/4" of clearance so the seat doesn't hit the door panel on the bottom. The "wing" will be close and hopefully won't need to be cut like the driver's side but I'm not sure yet.


First thing I have to figure out the receptable mount for the seat belt first. Yes, I am going to keep the oem 3 point belt just for the niceness of driving on the street. It's not too much more work imo and the Recaro ABEs have a larger slot which works nicely. 6 point harnesses will go in after I get the seat installed. So the issue with mounting the 3 point receptacle is that the fixed mounting point is shy of the seat belt opening. After thinking of different options, I ordered a seat belt extender to plug into the oem receptacle. While this isn't ideal it should work. I want to keep a soft strap for the oem 3 points because it allows easy swapping between 3 points and 6 points. If I have the 3 point receptacle hard mounted in the seat belt opening, it'd likely be in the way of the 6 point. Here's the oem receptacle roughly where it'll sit. The seat belt extender I ordered is 7" long.


For the driver's seat, it was easy to order a soft strap because I bought a brand new seat belt that uses a different buckle shape. I ordered it from seatbeltplanet. They can make a soft strap to fit their receptacle but not the 99 oem receptacle. Here's a shot of the driver's side belts. The 3 point can easily be moved out of the way to swap between 3/6 points. The 6 point side strap uses an eyelet bolt on the tranny tunnel area. Hopefully the seat belt extension works fine for the passenger side.


Not too much otherwise. With the heat I have noticed that boost pressure seems to be a bit lower. Not too big a deal honestly, but I'm going to play with boost control again with the BMM ecu. Nice thing about the discord is comparing notes with another fellow on there. Hopefully I can get the closed loop boost control working reasonably well. It has a PID controller for closed loop so hopefully I can limit the overboosting and avoid oscillations. *fingers crossed*

 

This is true.. I think the issue is that I already have too many vehicles to maintain (5) and I really don't want to add another. Unfortunately we can't ditch the minivan yet. I also feel like nothing is cheap anymore these days. I honestly don't know what a "cheap" tow rig would cost. But there's the initial cost, then ongoing maintenance and things it might need in short order..

I'm happy to be proven wrong though.. if there are some legit cheap options I'm all ears. "Cheap" is of course relative. $5k I could probably convince myself to add another vehicle, but I'm guessing it's probably ~$10k.

 

Really cool updates. Your kiddo with the laptop hooked up to TS is super cute, she'll never forget that. Great parenting.

Digging the street **** on your car, interested to see what you think about it. I've been happy with mine, worked great without any major front aero and seems to pair nicely with my mild splitter as well. I had the same thoughts of upgrading to the big **** someday, but personally have decided to drive the car more as-is for a while without making any changes, which sounds like what you are planning as well.

Stoked to see it on track soon!

And talking tow rigs, I've been rocking a 1998 e150 van. Other than storing the thing, it's crazy how decent it has been. I was expecting a lot more.. trouble, and hopefully I'm not jinxing myself with a trip coming up tomorrow, but this thing is awesome. Cold A/C, 5.4 with plenty of towing torque, camping space inside. My main complaint is with the age and safety concerns, but hey, otherwise I'd be driving a 1990 miata to the track so it definitely feels safer than that. I also picked up a brand new 2025 dovetail trailer for $3500 O.T.D. after 1 too many $600+ uhaul rentals. If I kept going down that route I was going to pay for the trailer in short order.

 

I have used this peel and stick patch material to patch some bolstering on my seat and cover up a repair to my door card. Easy to work with and has held up on my seat for a year or so.

Not sure if you could get away with a single piece for a hole that large, but two might do it and it would look a bit better.

 

Thx was following your thread and saw how you liked it and saw it in person last fall so figured it was the way to go. It's not super obnoxious on the street, and hopefully tames the rear down a bit.

I did a quick search for some old vans and it looks like some in better shape are closer to $10k than $5k, and who knows what else would be required. Definitely more than I'd want to spend but if you have one that's been reliable and paid for that's awesome. Everything's gone up a fair bit since covid, is what it is.

 

So I had a little time before the track this weekend and got the passenger seat and harness installed. The seat is a Recaro pole position ABE seat just like the driver's side. I like the PP's because they fit me well and are reasonably comfy. The ABE has larger holes on the sides for the oem 3 points. For the OEM 3 point I ordered a 7" seat belt extender and opted to just bolt it to the bracket. I thought I'd have to mount the oem one and use the extender but this worked out the simplest and best. I got it from here: https://www.seatbeltextenderpros.com...belt-extender/



The brackets I forget what brand they are but they seemed to work alright. I cut the top slots off and the seat belt anchor on one side as they get in the way and hit the cut edges with primer. I found the OEM bolts a bit short and fortunately found some other ones in the 10x1.25" thread that fit and had more thread. The seat brackets are 3/16" steel so thicker over the oem brackets and don't always sit perfectly flush to the mounting surface.




After the seat was in, I removed it to install the harness anchors. Not too complicated, just drill and mark. I also had to cut a hole in the passenger door panel to accomodate the seat wing on the seat.



I followed @SimBa 's advice and got the patches from Walmart. I'd say def a little nicer than the duct tape.



Finally, picture of the harnesses clipped on and seat installed. I ordered used/expired harnesses for the miata to save a few bucks on new ones. No issues these look to be in decent shape. I think only PCA is the only club that doesn't allow expired harnesses for HPDEs, most orgs don't care for hpdes. I like the clips as it makes it easy to remove the harnesses when not in use and switch back and forth between 3 and 6 points. I didn't snap a picture of the one latch point on the side, but I did it the same as the driver's side. I used the seatbelt mount point with one of the bendable eyelets.



It's going to be high 80's low 90's this weekend so it'll be a good test on track for the cooling system. *Fingers crossed* hopefully holds up fine. Just need to swap pads and car should be ready.

 

Definitely looks better than duct tape! Glad I was able to help out. I wouldn't be surprised if you find more and more uses for that stuff now that you've got some on hand. Surprisingly versatile stuff.

I'm surprised nobody has designed and 3d printed door cutouts/inserts. Seems like it would allow a cutout like that with more of an OEM look.

 

Ya I bet, I'm sure it'll find more uses. I was thinking the same thing regarding 3d printed cutouts and I'm guessing it's not a thing simply because of all the variables regarding seats. The seats, the position of the seats, the brackets used, etc. The cutout location could vary quite a bit based on the seat used and the position.

 

So this will probably be a bit long, but I'm happy to report the car held up really well all weekend and it was scorching hot. Saturdays high temps were high 80's and Sundays were mid 90s with no cloud cover.

So like all track weekends, I'm not sure what it is, but being fully prepped ahead of time and getting a good night sleep beforehand just usually isn't in the cards. This time was no different. Earlier in the week I decided to take Friday off and goto Kings Dominion with the family. It was a great time. I love Kings Dominion and we all like roller coasters. Water park is a lot of fun too with the heat. My favorite coaster at King Dominion is the Grizzly. I'm happy to see it's still here a good ~30 yrs since I first rode it. It's an old wooden coaster that shakes like hell and feels like you're gonna fly off of but that's all part of the fun. This is with the older 2 kiddos. The youngest is only 5 so she isn't tall enough but I'm sure she'll be riding with us as soon as she's tall enough.



Anyway, so we got to Kings Dominion a little later than planned and the kids wanted to hit more coasters and not leave early. I can respect that. I knew I'd be hurting anyway but figured what the hell what's another hour. We didn't get home till after 11pm, and like all fun filled days, they passed out in the car so had to carry the kids out of the van into their beds, but I guess I'll look back at these times as the "good ole days." Got to bed around 12am and set the alarm for 530. Fortunately I planned ahead enough and charged batteries a couple days ahead of time and gathered tools so the morning of I just had to scramble and grab everything and toss it in the car. Got to the track and parked next to my friend Dave and his racing buddy Callan. The car's still all nice and clean.



Did you see that? I got me some fancy magnetic numbers now! I finally used the HD vent covers and asked my daughter to make me some. They're not perfect, and like only a father can love his ugly child, they're unique and mine. I will say the magnets are not super strong, so I taped the leading edge to be safe, and they stayed on all weekend. I could've bought some nice ones online but these ones will be special to me.

So where to start on the weekend? First off it was f**king hot. I was lucky Dave brought his camper and Callan brought his trailer with AC, so getting out of the heat periodically made a big difference mentally. A big reason why I went was because I knew I could get out of the heat. I also had a nice spot in Dave's camper to sleep over Saturday night. Summit is just under 1.5hrs from my house, so I usually just drive home Sat night and back out Sun morning. It was nice to not have to do that roundtrip. This was a NASA weekend, and they raced in the spec miata series (which was quite a small group compared to what they're used to in SCCA). As expected Dave won the races and basically pushed Callan in the 3rd race to a 1st place win. lol These guys are pretty serious and got a good setup. Keeping their cars under pop up tents keeps them reasonable and not roasting hot. Like all racing, Dave's car had a bad rear wheel bearing after Saturday and he didn't have a spare but another nice fellow in his class had a spare and let him borrow it for Sunday. Quick swap and didn't miss a beat. The TV in the trailer was cool for reviewing some gopro footage and datalogs and getting pointers on where to improve.





Summit Main is my local track but I haven't run it a whole lot, I've been on Shenandoah a bunch. I think this is only my 3rd or 4th event on Main and I want to say last time I was here in my Honda I looped it back in 2020, so I had some cobwebs to shake out. It was a good one.

So like all track weekends, first thing I go over the car carefully at the track, check tire pressures (I set these Nfers sport R's to around 27 cold, that seemed to be decent), check the oil dipstick after every session or every other session, etc. The car didn't give me one bit of real trouble all weekend. After first session of Sunday I noticed the Junk2 throttle hanging a bit at times sporadically, but it wasn't terrible and figured I could manage it (throttle would "hang" around 2k rpm). I had typical gopro issues not loving the heat, and I think my external gps tapped out because of the heat as well on the 2nd Sunday session. Water temps were rock solid. I haven't pulled the datalogs off the ecu yet (I didn't pull out my laptop all weekend), but off the can gauge I don't think I ever saw water temps over 210F? I'll confirm that. Oil temps I don't recall seeing over 225F either. So well within spec and cool considering it was ~94F and blazing sun on Sunday. Very happy with the car. Being so hot, boost didn't look to be creeping like it did last fall, so boost looked to peak ~7psi according to the gauge, but I'll confirm everything in the datalogs later on. Good thing is based on my water/oil temps, the cooling system can handle some more heat (so maybe a little more boost in the future) .

The only real "bad" thing I had this weekend is the passenger triangle window lost to a rock, but that's minor and I'll replace it. Not sure what options are available but I'll look into it. Dave said it's an easy fix so no sweat. It happened sometime during the 3rd session on Saturday. I taped it up w/ packaging tape on both sides and kept driving.



I think I'll break this into 2 posts.. getting long. Next post will cover actual driving and car impressions..