Small but important update!

The transmission adapter plate has been ordered. I ended up going with a Domiworks adapter plate for the N55 8HP45 that I got from a RWD 2017 BMW X5. That specific N55 version isn't listed on their website, but they were able to custom make it for the same price as the N20 version but with a 5 week lead time. I was able to get it through tf-works for considerably cheaper than direct from Domiworks too -- like $200-$300 saved. The transmission was only $250 picked up with 80K miles. Now we wait...

In the meantime, my differential mount from KPower was just delivered. I need to reinforce the differentials arms too. I've still got a full set of poly bushings (suspension and diff) to put in as well. The Maxxecu is wired up except for the cam and crank sensors. I need to find some connectors that are appropriate to wire them in since the Maxxecu grounds them differently than the stock harness (feel free to give some recommendations, I've not looked into it at all lol).

I was going to try to start the car on the Maxxecu but after an hour of trying to remove the blown up 6 speed's bell housing, I gave up. I'm pretty sure to get the bellhousing off, you've got to fully disassemble it from the tailshaft inwards, and **** that. Additionally, I don't want to go through to pain of reinstalling my blown up transmission just to be able to start the car. I'll wait until the adapter plate comes in. It should be in before the end of August, so worst case scenario, you all should be hearing from me then.

Also, I'm probably going to buy the transmission flashing tool myself. My logic is that all of the shops charge an arm and a leg to ship it out or to flash your transmission themselves. I could likely charge the full price to ship it to people and upon return of it, keep $100 and send the rest back. After 3-4 people did that I'd be better off than borrowing one from a tuner, plus if future updates come out (which they should) then I won't have to double down with the tuner's fee.

The only things left that I need to pay for are the transmission mount (fab myself or pay someone, idk yet), the custom driveshaft, and obviously the transmission flashing too.

 

Hope you'll like the maxxecu.
I have a Maxxecu mini on my Nb and I really like it. its very easy to use imo.
Will however be upgrading to a sport next year I hope. I want DBW and tablet functions so I can remove my aftermarket gauges.

I too would like a zf auto when my 5spd ***** the bed, so im waiting for your opinions on it in a miata.

Edit: I wired my ecu to a stock ecu connector so i could use the stock wiring harness, will that work for you or you are going full custom harness?

 

Glad to see things are moving along. Really interested to see how this all comes together for you.

 

I am 100% looking forward to the extreme flexibility of the Maxxecu. Also if you're already upgrading, personally I'd just go ahead and spring for the Race so that you get knock sensor support. At least it makes sense for me to have that extra bit of protection at 26 PSI lol

I'm using the stock connector for everything except for the cam and crank sensors. Maxxecu (at least on the Race) grounds the cam and crank sensors separately from everything else so I was going to wire them direct to the sensor. I did speculate about taking the ground wire and connecting it to the normal sensor ground and then using the stock connector for everything. I emailed maxxecu to try and see if this was possible, which is suspect it is, but I never got a response. Its not a lot of extra work to just follow their guidance though, so I plan on just buying a connector and running the wires through the old AC holes.

 

I spoke to my tuner about knock sensors and why so few use it, and he told me that the noise in valvetrains and so on in race engines make it hard to isolate the knock. Easiest way to prevent knock is to go e85 afaik, sure you can get knocking with e85 aswell but its not very common

let me check my wiring diagram, and get back to you.
Its vacation times here in sweden, and as we have 5 weeks paid vacation, things tend to go slower during the summer.

 

I unfortunately dont have great access to ethanol. The nearest gas station that sells it is ~35 minutes away in Bristol, Virginia. It might make sense to use it for autocross and drag racing in Bristol, but it isn’t something I’d ever plan on daily driving with.

Regarding the knock sensor not being useful, is that more of a megasquirt thing? I’ve heard a lot complaining about megasquirt knock control, but I’ve seen mostly praise regarding maxxecu’s control.

edit: hopefully the Maxxecu team isn’t on vacation currently. I want my Swedish adapter plate lol

 

I see

The knock control surely works just fine, I guess it wont make sense in my car though as I will
run e85 with a flex fuel sensor.

nah I couldnt see anything about them closing for summer, I guess they are just understaffed right now

 

Watterson - just skimmed your thread - and to clarify - cuz I’m lazy - now you are:

using Maxx ECU, with their ZF8 control
using a -45 instead of a -70 because Maxx now controls -45’s too.
are running a torque converter.
you are running a Kraken cast mani - top or bottom mount?

You are ahead of me! With the -45 instead the NB do you think you’ll have to cut the tunnel for 3” exhaust clearance like the pic on the other thread?

keep charging man live your progress.

 

See responses in red above. Regardless of how things end up going, I plan on documenting things as well as possible. I've got a good feeling that these swaps are only going to become more popular in the future -- at least on other cars. As soon as I get the Domiworks adapter plate in, you can expect some images and measurements. Also, you might still beat me to finishing things up. While I've got the expensive parts purchased, I still need probably another $2000-$2500 in parts to finish everything and practically nothing has been done except for the removal of the old transmission. I also have quite a few concerts/festivals in the next 2 months that I need to get hotels for as well which takes away from the car's budget...

Edit: Also, there are not any Dodge 8HP to BP adapter plates yet, but this may change in the future. There could be significant improvement in this market for US customers. Not just for Miata's but other less common engines commonly only have adapter kits for BMW housings. We need a US-based equivalent of Domiworks lol

 

Well there are other ways to get around the transmission tunnel space issue...

SidePipe!

Moar SidePipe!

EvenMoar SidePipe!

 

I’d daily Ryan’s hyper Miata in 100* weather before getting seen in one of those cars.

been installing a 6hpz28(?) from guruwerks into a 335 the last few weeks, have no idea how you’re fitting one in a Miata!

 

Just found this thread.

I'm running a MaxxECU Race as a Piggyback PNP unit in my MSM.

I have both home and Crank grounds tied to sensor ground, works great.

 

why didnt you use H2 (VR GND)?
just curious

 

Sorry for a late response, however this is how i wired my maxxecu mini, trigger (a1) to 2J in the pnp connector, trigger gnd (a2) to 3C
and home/cam (H4) to 2H, but in my case i use digital in 1 as home/cam as the mini lacks a separate home/cam.

afaik its recommended to use the shielded wires all the way to the crank and cam sensors but i wanted to go as pnp as possible and it has worked fine without any excessive noise afaik. Im only running 185whp @ 10psi atm

 

just looked over my notes.
I believe I tied VR/home Ground to sensor ground.

As they're hall sensors I wanted the potential for the 5v to operate the sensor.
and for the maxx side to read correctly, tie the vr ground to the sensor ground. as well as Knock Gnd. (E1, H1, H2)

 

Last Thursday I reached out to TF-Works about my adapter plate, and I got a response back this morning. My adapter plate is still 4 weeks out... Something about delays with the flywheel. Maybe getting the aluminum or whatever has been difficult. Oh well.

I'm thinking about taking the cutting wheel to my old transmission's bellhousing to bolt up the starter and at least get the car's engine running. Other than than, I've not done **** with the car

 

Over the first weekend of September I got the car to idle on the Maxxecu. I was able to bolt up the starter by using the blown up 5-speed to make a starter bracket. I somehow didn’t get a picture of it by itself, but I got one with it while acting like it’s a phone lol


There were a few speed bumps along the way. Namely I wired up the sensor ground to the wrong pin. The stock ECU had two sensor grounds, I can’t remember which was which but the two pins were 3C and 3F. I also used the wrong pin for the fuel pump relay just by user error. I got those fixed up and it started up fairly easily.

It didn’t idle though. I used idle values from my megasquirt tune, but the Maxxecu doesn’t have a fly back diode, so those numbers needed to be greatly increased to get a stable idle. I ended up idling around 78-80 duty cycle compared to like 50 with the megasquirt.

Once that was fixed, it would idle, but it was misfiring fairly badly. I ended up changing the spark plugs, but it was still there. I pulled the plugs and none seemed wet but cylinder 3 had a slightly darker color to it without any white on the ceramic part while the other three cylinder had white areas.

At this point I thought I had it narrowed down to a single cylinder. I checked the injector resistance using the Maxxecu diagnostic features (which are awesome btw), and they were all 12.2 Ohms with cylinder 3 being 12.4. Nothing out of the realm of possibilities for a good injector. I also checked spark by pulling the spark plugs, putting them back into the COPs and grounding the outside of the spark plugs to valve cover bolts. All cylinders fired when they should (still batch ignition).

So with the injectors all showing an acceptable resistance and ignition coils working, I tried increasing the dwell to see if it might fix the misfire. I got up to 5.0 milliseconds without any change, and considering I only ran like 3.5 or so under 26+ PSI and 11:1 or richer AFRs, I figured that wasn’t the issue. I went and got a new coil pack from autozone to trouble shoot with. I replaced cylinder 3s COP, but it had a misfire. I even tried adding up to 30% fuel to cylinder 3 in case there was a partially clogged injector, but there was no change.

At this point I started getting suspicious of the injector timing settings. I believe the basemap used “Untimed 720° sequential”, but I also tried regular “Sequential 720°” and “Sequential 360° (4-stroke)” but to no avail. I’m not 100% sure which is best, but I left it on Sequential 360°. If anyone has input on which is best, please chime in. I struggle to understand the differences between them.

At this point I started pulling COP connectors to find confirm cylinder 3 was misfiring still. At this point, cylinders 2 and 4 were completely missing, and pulling cylinder 3 made the engine die. I don’t recall my exact injector settings at this point though, but I think they were causing this. I plan on sitting back down and messing with it more this weekend – I’ve just not had the time since then.

My next idea is to jiggle the wiring harness where I soldered it to the stock ECU’s connectors. I’m suspicious of an intermittent connection issue on the fuel or ignition side of things. The engine isn’t losing sync or anything either. I’ve obviously not been able to test the engine under any real load yet, but I did notice it didn’t misfire as soon at it started up a few times, only as it idled down. Lambda is at 0.86 to 1.00 this entire time as well. Maybe it could just be a small idle misfire? I’ve got a clip that I can upload to YouTube and link here once I make it home if that would help. I’ll also upload my tune, but where it’s Maxxecu, I don’t exactly expect a ton of help.

edit: also the alternator control seems to work relatively fine with the default PID settings while flicking the lights/high beams ons. The 1200 Ohm pull up resistor seemed to do the trick.

 

want me to send you my map to try on your car?

 

After spending so much time on limiter at autocross this weekend (and previous weekends) I'm even more eager to see this project come to light.

Rooting for you man! I'm sure the debugging/tinkering phase will be a pain, but once it's going I think it'll be a game changer.

 

Post updates once you continue the diag! Good work so far, we know you got this.

I'd use a test light on the cylinder 3 injector circuits as well. Make sure you're getting power and pulse at the connector. Have you confirmed the cylinder 3 injector clicks with power and ground applied directly from the battery? Assuming it does, I might get the injectors flow tested as well. If you've got spark and injector pulse/solenoid activity, and the miss was only at idle, the #3 injector flow might be out of spec.