Holy hell, you win the crack competition I was trying to avoid doing ducts on my car at this stage in the name of "aErO". Figured I'd add them once I'm making more power. Maybe I should add them to the list, though. It's not like the car's outrageously slow as is...

I ended up bumping my registration back to tomorrow, as it was slated to rain at the track today. This ended up being a good thing, as I needed to fix more things on my car than I thought..

I replaced the valve stem on my leaking tire earlier in the week and drove it to an update training course I had 45 minutes away. I brought a bicycle pump in the passenger seat just in case the leak started happening again. 30 minutes on the freeway and no loss of air pressure, sweet! Unfortunately I celebrated too early. As I was driving home, my other front tire started slowly losing pressure, dipping under 20psi. I pulled over and yep, the valve stem was audibly leaking. This one you could actually wiggle around and hear the leak increase and decrease. At this point, I know the stem failures were unquestionably due to the extra weight of the pressure sensors I was running in place of the standard caps. I pumped the tire up to 35psi (probably hilarious for onlookers on the freeway), drove it to work, and replaced the valve stem on that tire as well. Then I took all the tire pressure sensors off of the car and replaced them with standard valve caps. Note made: definitely gotta run aluminum valve stems if you want to use those pressure sensors. I'm sure at speed, they were trying to tear my standard rubber valve stems in half lol.

Enough about boring things like valve stems, though. I was lucky enough to literally wander across a piece of corrugated plastic at work earlier this week, and decided to use it for a little experiment I've been wanting to try on the car for a while. I've been musing lately on what other potential aero improvements I can make to the car, and luckily, Miatas have a lot of places for improvement. I want to make some bigger skirts, and am considering getting my hands on a CCP fastback one day, but the low hanging fruit I've really wanted to mess with is a trunk extension. A la Ryan Passey's HyperMiata.



I actually messaged Ryan about the tail extension via the HyperMiata page on FaceBook and he responded surprisingly quickly. He added the first rendition to his car around 2013 and said it did make a finite (small, but finite) decrease in drag and increase in rear downforce. Good enough for me. I started cutting up the plastic sheet this week and used it to make a template for a later rendition.



Didn't really get a good photo but that's fine because it looked pretty crappy anyways haha. Luckily the paint on this car is already haggard so I had no qualms about drilling holes in the trunk. Used some random strap metal I had laying around to make supports for the rear of the extension. My rear badge is missing so I was able to run nuts and bolts through the existing holes it used to clip in to. If the extension becomes a permanent addition, I'll use some sort of sealant to make sure the trunk stays watertight.

I was expecting to complete the project next week but the world had other plans I guess. Cracked one of my mountain bike wheels while riding early this morning then shortly after it started raining hard outside. I said screw it and went over to Industrial Metal Supply. Grabbed a 2x4 sheet of .050" aluminum and 8ft of 1/2" aluminum angle for a little under $40 and got to cutting in my garage. I ended up finishing and bolting the aluminum extension to the car a couple hours ago. It's still a little rough around the edges, but I'll clean it up if it performs tomorrow. Still need to add the aluminum angle as a gurney flap, but I'm actually pretty amped with how it looks for a first rendition!



Tomorrow should be a perfect day for back-to-back testing. Temps are only supposed to fluctuate 10* the whole day and The Circuit has plenty of high speed straights where drag reduction should be easy to detect on the GPS data. I'm going to run all my sessions on the Aim and see if I can tell any difference with the extension installed. If it performs, I'll clean it up, maybe paint it, and run it for the remainder of the car's non-TT5 track days this year!

 

Interesting about the valve stems. I've had good luck with the screw-on valve stem cap sensors, but I only used them on my truck and trailer, not the race car.

--Ian

 

I gotta imagine the failures had something to do with the fact they were on the fronts. The rears are fine. Extra heat generated by the front brakes coupled with the fact that the stems were being acted upon on an additional axis? I did get my front wheels hot enough last weekend to melt the adhesive off of the wheel weights…

Probably best to spend time elsewhere rather than digging deeper into it, but yeah, strange failure lol.

 

I'm starting to think I'm overusing the phrase "aNoThEr SiCk wEeKeNd tRaCkInG tHe cArrrrr!", so I'm sorry about that. Gonna take a break after this weekend to give the car a full checkover and work on some other minor modifications.

With that being said, it was another sick weekend tracking the car! While not a Miata-centric track on paper (lots of long straights into slow corners into more long straights), the "Circuit" track at Buttonwillow was super fun and the car was able to hold its own against the higher power cars in the crowd. Ended up running a way faster time than anticipated, edging out my buddy Frankie's time by exactly a second!

Hindsight 20/20, I'm pretty sure this was actually a 1:57.3 lap. Not much changed for the 1:57.0 except I apexed turns 2 and 6 later, which proved to make a pretty solid improvement.

The pre-track ritual even started off pretty stellar. At my NA's final track event last March, I met a guy named Hamza who was fielding a 370whp turbo GT86. We got to talking and pretty quickly realized two things: we had the same level of ADHD, and we lived about a mile from each other. I haven't tracked with him since then, but I saw his name on the registration list and messaged him Saturday saying I'd see him Sunday. He messaged back and said he and his girlfriend were camping at the track that night, and would be making Korean BBQ if I wanted to stop by. I told him I'd be getting in late, around 10:30, but that I appreciated the offer. Well to my pleasant surprise, when I rolled in at 11, they were outside their trailer with a fire pit going and were just starting to cook. Ended up hanging out with them eating KBBQ until 12:30 Saturday night. Not a bad start to the weekend.


I suppose we've all seen enough photos of this car trackside on a Uhaul trailer at this point.

Sunday morning rolled around and I had my goals in place. Though I know I should just be out here enjoying myself, I really wanted to put down a time I could brag about to my friends. I know Frankie put down a 1:58.00 here a few weeks ago, and I had a mental short list of some other buddies' times. Being that this track only opened in January, it's really cool having a clean slate and developing perception of what a fast time is. The neighboring "CW13" track has the coveted "Sub-2" that everybody wants. So far, a Sub-2 on this track seems to be a bit easier to attain, but is still a quick baseline. I figured I'd be happy to come within a half second of Frankie, and hoped I wouldn't flounder and wind up three seconds off pace haha.

I was originally signed up for Saturday but changed my registration because it was going to rain all day. Sunday's weather was much better, but we still did get a little rain Sunday morning. First session I was gridded in the middle and was lucky enough to have an S550 Mustang to pace off of. It quickly became obvious that almost every corner on this track was a very late apex, with the goal being to get on the gas as early as possible in each of the many long straights. I ran the whole session and managed to get a 1:59.3 on lap 6 or 7, before dropping back into the 2:00's as the rain finally started saturating the road surface. Great start! I jokingly shot a text to the Miata bros letting them know I was hot on Frankie's heels.


I can't tell how much my air dam is warping or how much is just a weird reflection. I have some pieces of angle supporting the sides already. Maybe it needs more in the center, though.

Second session I improved a bit more, still erring on the cautious side of things. There's a bunch of spots on the track that are high speed and high risk if you have an off, and I wasn't ready to start fresh with a new car because I went for glory on an HPDE day. There's way more barriers on this course than any other one around. Actually, most of our tracks only have one wall right on the front straight. Anyways, session three everything started clicking for me. Turns 9 and 10 right before the finish are fast and a little scary, but I started to figure out that if you take 9 at the right speed, you could take 10 close to flatout and carry all that extra speed with you down the next 1,600ft straightaway. I saw the Aim flash a 1:57.84 after a few laps and did a little mental celebration. Then this happened:


Oops. Ok, I found the braking point for turn 8. Got lucky with that tire wall, but the entire underbody of the car got slathered in sticky mud, as did all of the wheel wells and about every other orifice imaginable.
Side note, though, that turn was the most fun one on the track. 80+ mph straight into a decreasing radius sub-45mph hairpin. Trail braking world champs. So satisfying pulling that section off smoothly.


All of the crud that came out of the front wheel wells only.

From here, things kept getting better. Some more things clicked for me and the next session I laid down a bunch of successive 1:57.3's. None of the laps were perfect, though. I knew there was more. Didn't think I'd be gunning for a 1:56 but it was within reach.


Quite possibly the most consistent I'll ever drive in my entire life.

The next session was the final one. I had a good feeling I could make another improvement, just had to put everything together with minimal to no mistakes. Conditions were perfect: it was still cloudy and maybe 60*F out, there were only six cars on grid, and any chance of more rain was long gone. I pulled out at the front of the pack and didn't see a single other car the whole session. I finished up a flyer on lap 3 or 4 and saw the Aim flash a 1:57.06. Ahh, so close! Knew I hadn't absolutely nailed every corner for that lap so I came around for another. 1:57.01! Tried to go for another flyer but made a couple mistakes then two laps later the car started to fuel starve so it was day over. I was bummed to have come that close to the 1:56, but still very satisfied. But wait, I remember what you guys said about transponders being more accurate than the Aim. SpeedVentures does gridding via transponder times so I'd been running it all day. Maybe if I go to the live timing I'll find a 1:56 next to my name...


Ahh dude, you gotta be f*cking kidding me!

Oh well, it leaves room for improvement next time. Overall very good day. No issues with the car, minimal drama on track, and the social aspect of the weekend was on point too. I'll outline the only hiccup I need to address with the car as well as my "findings" on the tail extension in a later post. Onward!

 

Nice lap . Were they getting fussy about how wide you go on the exit of turn 1? When I was there in January they ran a line of cones from the pit exit on the test day, but they were gone in the race and there's more speed in turn 1 if you carry it all the way out.

Also turn 2 is banked a bit on the inside, so I was taking a tighter line on entry because I found there was more grip there. That was the first weekend it was open though so it was a very green track.

Yeah, 9/10 are initially deceptive about how much speed you can carry through, and 10 is visually confusing because of the pit lane entry that happens right before the fast left onto the straight. I'm am curious, though, why you're entering turn 10 from about half track? It sounds like you're having to lift at least a little for it, which suggests setting up further to the right on the entry would let you carry more speed. I'm headed back there next Monday, looking forward to trying to improve on my time.

As far as transponders go, it's not so much that they're necessarily more accurate, just that since they define S/F as being in a different spot from the AIM systems you can end up with small differences in lap time.

--Ian

 

Yo, thanks Ian! Plenty to improve upon, but I'm pretty happy with it.

As far as T1 goes, no fuss at all regarding how wide you exited there. Unrelated but possibly related, I heard there was a wall there for the first few weekends in January but they took it out due to a collision? Was that not there when you went? At any rate, nobody said a word about how wide you could exit. I wanted to exit wider actually, but every time I hit the apex, it just seemed easier to keep turning into the next straight. I tried a few different lines through that turn too. Maybe I just wasn't able to figure one out with an optimal super wide exit.

RE: 9/10, I felt like I could carry a little more speed into and through 10 by holding a little more exit speed through 9, at the expense of being able to get all the way back over to the entry of 10 in time to turn in. I did find later in the day that I could take that exact line and not lift at all through T10, it's just scary haha. I suppose exiting 9 slower and tighter would allow you to get on the gas earlier and stay matted through 10 easier due to the better entry. Maybe I'll give that a try next time.

Good luck next week! I still gotta catch you at a NorCal event one of these days.

 

Yeah, I was there the first event (CalClub SCCA Majors in January), they were still figuring things out. There was a big tire wall at the end of the front straight (protecting the pit exit), although it didn't go quite as far as the track out point. They were concerned about people tracking all the way out and encountering other people exiting the pit lane, which is why they put the cones. Disclaimer, this is not a great lap -- I don't carry enough speed through 4 so don't wind up using the exit, I'm chickening out on the braking for 5, I'm too early to the apex on 6, and I hadn't figured out 8 yet, but it demonstrates the cones/etc.


And yeah, if you have to give up a bit of cornering speed through 9 in order to set up 10 better then that pay off all the way down that long straight!

You picked up the track better in one day than I did! While it's not as technical as the original track or Sonoma, there are a bunch of subtleties to the new one that are interesting.

As far as events go, I was thinking of doing the Speed Ventures May 18 Laguna date that has the MTTC on the schedule but alas scheduling doesn't work out (I'm going to BW classic to do WRL testing the next day). I'll probably do the NASA SoCal event at BW in October (the June one is scheduled on top of a NorCal race -- stupid of them to do that).

--Ian

 

Thanks for dropping your lap vid! That's crazy how long the tire wall extends. Makes sense, though. Incoming traffic at the track entrance is right in your blind spot as you merge in. And that braking zone into T1 is violent. I didn't do enough homework before the event and now I'm trying to go back through as much footage as possible to see what everybody else is doing. I shouldn't have mentioned my times! Appreciate your praise but it's a lot easier to figure out a track in a five second slower car hahaha.

Agreed on the technicality aspect of the track too. I thought it was going to be almost like Big Willow with very little tech aspect to it, but that wasn't the case. Pleasant surprise there. T2/3 and T8 especially required a lot of work to get right (for me at least)

I was going to try and run Laguna on the 18th as well but just found out I got a wedding that weekend. Would rather be at Buttonwillow that day too if given the option lol. Barring any serious car troubles, I'm planning on making it to BW for that event in October, probably with a few buddies as well. I'll keep the thread posted with those plans as the event gets closer.

 

A couple minor things on the car this week, but nothing too earth-shattering.

As stated in my last big post, I only had one issue at the track last weekend. Unfortunately, that issue was totally self-inflicted haha. As soon as I passed 70mph on my first lap, the car started vibrating semi-violently, up until about 90-100mph where it smoothed out a bit. Having bent at least 3-4 wheels on track at this point, I've gotten too used to this sensation. Although this time it felt like... multiple wheels were flat spotted? There's no way. I pulled the car into the pits, put it on jack stands and let it idle in second gear. No flat spots on the rear wheels. Rotated the tires. No flat spots on the front either. No play in any of the hubs. No flat spots on any of the tires. After longer than it should have taken, it hit me. I hadn't rebalanced all of my wheels and tires since removing the tire pressure sensors. Well that was annoying but at least I felt confident in the car after that realization. There's a tire shop at Buttonwillow where I could have had them balanced but I figured they probably charge out the wazoo even for small services like that. I just ran with the unbalanced tires for the rest of the day and brought them to work with me on Monday. Sure enough, the balancing machine said each tire needed exactly 1.5oz of weight on the outer edge. I rebalanced all of them and took the car up to 70+mph on Tuesday. No more vibration. Thank god this was an easy one haha.

Another thing that potentially needs addressing is the car's brake system, and the addition of ducts. I'm running some big ol' Wilwood Superlites on the front of the car with some big ol' 12.7" rotors from an RX8 (stock rotor size is 11.5"), and figured these would be more than adequate for the entirety of the car's life. They've been pretty solid so far. I'm running Wilwood BP10 pads for street use, and Hawk DTC60's for the track, but have been running the DTC60's on the street too for the last few months. Got ~12 track days out of the first set of DTC60's, which was pretty good. However, on this second set, I'm at 4 track days and a handful of canyon runs and they're already worn almost halfway through, and have tapered pretty badly. New pad thickness is 20mm and these are ~11mm at the narrowest point of the taper.

Now the last two tracks the car saw were really hard on brakes. I guess the car is making more "power" than when I initially got the brakes, but I think I've got enough reason here to add brake ducts. That'll likely become a project in the upcoming weeks.



I also completely glossed over the effects of the trunk extension last weekend. I've decided to put a little bit more time and effort into that project as it did make a noticeable difference on track. Immediately, I was pretty sure it increased downforce at the rear of the car. Last weekend's track was overall pretty high speed and the car felt like it was more understeery right out of the gate. Unfortunately, I don't have any great data proving that it reduced drag. I pulled the extension off for the third session and my top speed dropped 1mph, but this was also the only session where the sun came out and it was a bit warmer. I can definitively say that the rear end was a tiny bit more loose at speed this session, though. Meant to do some more back to back testing but I was within reach of that 1:56 time and decided to leave the extension on since I suspected it was helping a tiny bit.

This week I added some 1/2" aluminum angle to the sides to stiffen it up, along with a little gurney flap along the trailing edge also made out of that same 1/2" angle. I also painted the front 2/3" up to where the extension passes the wing uprights. Now if you squint your eyes from 20 feet away it almost doesn't look like just a piece of scrap metal screwed into the trunk.




Disregard the one 10mm bolt sticking out of the right side, I lost the button head bolt that went there and the rest are in the van.

The spoiler looks much better. Could probably use a little more cleaning up but I'm happy with it for now. In the coming weeks, I'm going to build a larger splitter to try and exploit the increase in rear downforce. In theory with the trunk extension and a larger splitter, I should be able to increase overall downforce for a zero increase (or even possible decrease) in drag. My current splitter is only protruding 2" from the airdam at its furthest point, so I can add another 2" all around and still stay TT5 legal.

I got the DW300 in the mail this week, so might drop that in this weekend and see once and for all if the car's really running out of fuel pump on e85. In Vegas my AFR's stayed in the mid-12's all day. Last weekend, it was cooler out, and I saw AFR's rise into the 13's at redline, but am not completely convinced it was due to a fuel pressure drop. The NC has a couple semi-strange strategies that happen at WOT/Open Loop. One is the factory enleanment table, which leans out the mixture in OL when certain conditions are met (I do not know the exact conditions but obviously its temperature/knock related). It's also got a strategy that richens the mixture the longer you hold WOT near redline. At WSIR with the 5 speed, my car was above 5.3krpm in 4th gear twice per lap for ~15 seconds at a time. After a few seconds, I could watch the mixture richen from 12.5 eventually making its way down to ~11.2 before letting off the throttle. This doesn't happen in any lower gear. I think it's possible that the factory enleanment table is still enabled on my car/tune, and that's causing the mixture to go a little lean above 6,500rpm intermittently.

But regardless, the car's still gonna need a bigger fuel pump eventually so the DW300 is going in. I'll probably fuss with that at some point tomorrow and try and round up some buddies for a drive on Sunday.

 

FWIW, I've never bothered with balancing race tires. Between the wear rate, movement on the wheel, and the clag they pick up I've always figured it wasn't worth the bother. I am interested in hearing others' opinions, though....??

Also, mine are track only, and smaller/lighter wheel/tire sets...

 

Dude I felt the same way with my NA. Always read about how sensitive Miatas were supposed to be with tire balancing but never experienced an issue with it. The balancer showed my NA's wheels were way out of whack a couple times but I couldn't feel anything at all on the road haha. Same goes for flat spots (wheels and tires), I've had a couple substantial ones that were almost imperceptible while driving.

Gotta imagine it's something to do with the diameter of the wheels on the NC. 17" vs 15" and plenty more weight being thrown around..? After balancing, the vibration went away entirely.

 

Good stuff Zak! I dig the tail extension.

regarding balancing, I can tell right away when one of my wheels spits a balance or flat spots but I only really cared when I drive to and from the track. Now that I trailer the car I left them flat spotted and imbalanced since there is so much going on already at the track as roda said. All that said I too never cared to rebalance the tires due to wear, only if I flat spotted them bad enough to shake me about, at which point I was getting a new tire.

 

Interesting. When I used valve cap sensors I never noticed a balance change, but it makes sense. Again I only used them on the truck and trailer, which is going to be a lot less noticeable.

On the Miata I scraped a ton of weights off the wheels with the brake calipers and never really noticed much difference. On the BMW, if I mount Hoosiers on the cast Apex wheels then they'll move like 120 degrees on the rim in the first couple heat cycles, and that's REALLY noticeable on the front. 15s vs 18s, so maybe there's something to the diameter being a factor.

--Ian

 

I gave up on balancing track tires. You're always picking up clag, losing a weight, or flat spotting. Then there is just wearing much faster than you would in a street tire and therefore the balance changes throughout the day.

I guess a bent rim would be an exception, but should usually be replaced if bad enough to be much trouble.

I often played with used slicks when available and they always had clag on them. They also had a very light carcass, so weight wasn't a big deal.

 

This is funny, different experiences across the board for all of us haha. I agree all you guys, though, it's hard to stay on top of balancing track tires since they're constantly getting shaved down. Again, it wasn't an issue on my NA. It also hasn't been an issue on my NC, although it's weird that only 1.5oz of weight was enough to make the whole car shake. I took it up to 100mph a few times this weekend and zero vibration, so it was the tire imbalance(s) causing that last weekend.

120 degree rotation on the wheel during the first heat cycle, holy hell that is something I'm glad I do not have to deal with haha.

 

So Friday night I had some spare time and was going to pop the DW300 in. Got to the last two phillips head bolts holding the fuel pump hangar in and they were both frozen into the tank. I don't have a cutoff wheel at home to slot them for use with a flathead screwdriver, so I was dead in the water and had to put everything back together. Damn. Now I don't have any progress to make on the car.

Or do I?

Well, I finally took the plunge. Told myself I was going to simplify my life and outsource the tuning of this car indefinitely. I actually lasted a good 7-8 months before breaking that promise and deciding I need more things to tinker with. So yeah, this weekend I modified the OEM NC base map and made my own tune for the car so I can d*ck with it myself. I haven't had any serious issues working with a remote tuner, but it's definitely inefficient. There's been a couple times that my tunes have shown weird quirks that I could've easily tweaked out in minutes if I were still on a Megasquirt.

I've been reading up on the NC's ECU strategy for months and luckily the online community has helped expand the knowledge base a ton in the last few years. There's a small group of dudes who released a completely free application called ROMdrop to allow users to crack and tune the ECU themselves. They also released a huge how to guide and are active on the ROMdrop FaceBook group helping folks to use it. I already had the ECUtek software, so I didn't use ROMdrop, but I leaned heavily on their documentation and ECU definitions. ROMdrop guide here: NC Miata Tuning - RomDrop Edition

So a quick disclaimer: If it's not already obvious, I'm not an expert at this. I'm regurgitating information I've gathered on this subject recently from many different sources. None of this is stuff I figured out myself. I just wanted to share all this because I I found it interesting, and I haven't seen anybody outline how the NC's software works on here. Obviously, I'm going to leave some gaps here, but I'll try my best to fill this post with as much pertinent information as I can.

Alright, so any tune you create for this thing is just a modified version of the ROM for a 2.0L MZR engine. The 2.5 and 2.3L Duratecs are just upsized versions of the 2.0 MZR, and all of the MZR sensors are reused on the larger engines if you swap one into your NC. You can drop a 2.5L into your NC, turn the key and the stock 2.0L ROM will run the engine, albeit suboptimally.

So when you set the tune up for a 2.5L, you have to fool the ECU into thinking it's still controlling a 2.0L engine. You need to change two things in order to do this: The MAF scaling table, and the required fuel. Both are easy changes to make. Take the entire MAF scaling table and multiply it by 0.8 (2.0/2.5). Now the ECU's load calculations will be correct. Same goes for the injectors. Take your cc value and multiply by 0.8. Now the ECU will scale up fuel for the increased displacement.



There's two MAF scaling tables. ECUtek says to set #2 to the same values as #1. I'm not going to pretend I know why this is necessary.

For my setup, scaling the fuel injectors was a bit more of a task, since I'm running the ID1050's and e85. To my dismay, I actually had to bust out the calculator and do some math. The ID1050's flow 1236cc of fuel at 55psi. 1236 x 0.8 = 989cc. I then took that and spitballed a guess at the fuel increase I'd need on e85. 989 x 0.7 = 692. I put in 692cc for the injector size, then punched in the dead times for the ID1050's. Since the car uses a returnless fuel system without a fuel pressure sensor, the ECU has a table that multiplies injector scaling based on manifold vacuum (oh right, the engine has a MAP sensor in addition to a MAF). I left the stock values in that table.

I also went back to some previous logs and adjusted the cranking pulse width to what the car was running with my previous tune. Set cold idle to 1,200rpm tapering down to 1,000rpm hot as the cams in the engine won't play nice with the stock 750rpm idle.



Said a quick prayer, turned the key and the engine fired right up. Got lucky too, fuel trims at idle showed only five percent! Not bad, I didn't expect the car to run on the tune at all that night.

Yesterday I did some more work on the tune. There's some features that are a little foreign with this thing, but lots of things that are simpler than with a standalone. Idle, for example, doesn't have any settings to mess with. There's a table for idle ignition advance but that's it. I didn't touch that table, just set idle where I want it and the ECU hits it. Same goes for VCT advance and EGO/fuel trim correction. The tune uses all of the OEM strategies so that simplifies things a bit.

I'm not gonna lie, I just looked at some logs from the previous tune and copied over as many VCT, Ignition, and manifold runner control datapoints as I could into the tables on my new tune. Still got some work to do there but for now I've got all the WOT cells filled with what the car was running previously. I'm not sharing the tables, selling the information, or tuning anyone else's cars, so I don't feel any weight on my conscience for it.

Onward. So the ECU strategy uses the MAF for fuel calculation. The raw MAF sensor reading is the primary input for fueling, then there's a "load scaling" table that multiplies the pulse width based on RPM and the load reading. I don't know if it gets this load reading (g/rev) from the MAF or the MAP sensor? Basically, the table is used as a PW modifier to fine tune fueling in different areas where the engine is more or less efficient. There's no viewable VE table so all of your fueling adjustments are done by the load scaling table. I've heard/read that fueling changes shouldn't be made by changing the MAF sensor scaling. Maybe you guys know more about that.

There's a load compensation trim table available as well, I didn't know what to do with that so I left it zeroed. You also have two engine load limiter tables that need to be modified if you have cams, exhaust mods, etc. The ECU will limit throttle opening past the max load limiter if it's not increased. Could be useful if you needed to create a flat power tune...



I spent an hour or so tweaking the load scaling table yesterday. Unfortunately ECUtek (and any other tuning suite for the stock ECU) requires the entire ROM to be reloaded if you want to update the tune. Loading an update from start to finish takes about 5 minutes with the key on and engine off. Kind of a pain you can't make live changes to it like in TunerStudio. I ran the car through a range of RPM's and loads in closed loop, ran some datalogs, and adjusted the load table based on the fuel trims the ECU was showing. Surprisingly, the ECU wasn't leaning on the fuel trims too hard to hit AFR targets, but I did make a handful of adjustments to get them closer to zero across the board. Currently most of the low load/cruise areas of the map are running 7% or less fuel trim/EGO compensation. I'll do some more work on it this week.

Today, I got to some of the more fun stuff. WOT and high load fuel compensation. This was more straightforward. The ECU goes into open loop above 5k rpm or 75% accelerator input (although you can adjust these too). For WOT tuning, I just did a bunch of pulls and looked at the raw AFR on the datalogs. Got fueling to the point where it was pretty stable in the mid-12's all the way across the rev range, although I still have some more work to do. AFR's will hit mid 12's at 185* coolant temp, high 11's at 200* coolant temp, and just skirt the 13's at 175*. I'm gonna have to review the logs again this week but I gotta believe there's some coolant temp modifier for the fuel table that I might need to tweak. However for the afternoon, the tune was workable, and I was able to rip the car in the canyons no issue! Took a few more datalogs and will review and keep tweaking this week.



I'll keep messing with the tune this week and will keep the thread updated with what I find. I've actually got a couple more tune-related things to share but I think this post is long enough already. More to come!

 

interesting stuff - thanks for the details.

 

Interesting and very relevant NC tuning info! I'm sure @redursidae is already taking note

 

Thanks guys! Really excited about this haha. Had a bit of a love/hate relationship messing with the standalone on my NA (skill issues mostly, lol), but it feels so good to have control over my own tune again!

@redursidae probably already has more insight on this than I do

Got some more interesting tuning bits/updates coming later this week. Just gotta make a couple more tweaks and organize my thoughts!

 

Im always watching even if I dont respond 👀.

Im familiar with some of the strategies OEMs do, but no direct experience with the NC and ND ECUs yet. Keep the updates coming!