ECU Upgrade Options for '88 S4 NA
 

I'm starting a New Thread to Explore What's Old & What's New with ECU's for my ancient '88 S4 NA.

I'm basically stock with an RB True Dual Exhaust & would like to be able to pursue "Various" Upgrades in the Future.

I'm interested in Forum Members' Experiences & Opinions about a Sustainable Upgrade Path & the Various Failings of Past Experiments.

Simplicity vs. Complexity

Ease of Install & Ease of Use.

Support & Compatability?

I'm not intending to build a Race Car for Competition or make outrageous HP numbers. I have a Street Car & would like to keep it that way.

Proper Functionality & Monitoring/Tuning Ability without paying for Dyno Time is worth something extra.

Using my existing harness is a stong benefit.

Eliminating the MAF is worth paying something extra to me for possible upgrades.

I'm also looking for the ECU pin-out function list on the Stock ECU for the '88NA so I might get a Better Understanding of WTF else my ECU is up to, other than being trapped in it's own Factory Settings. For some reason my Searches came up with NADA...

https://www.rx7club.com/engine-management-forum-37/
Here you go, since its hard finding stuff

i hate answers like the ones above... you have a valid question that i wish i could be answer, but if you ask t haltech forum they will sell you the best haltech for your goals. same with aem, or adaptronic.

i choose ms3-pro, price and function list are great. my 2nd choice would have been the adaptronic e1280s, and i may still end up with one of those also.

before the ms3 pro i was all rtek. and if your goals are 350 or lesss, stick with tried and true r tek.

another reason for me getting the ms3 pro is i am a tuner and 2 other guys have bought them locally and are going to get me to tune them, so i wanted to be familure as possible with it. once i downloaded the software and started playing around with the features i saw it was a fit for me and most of my goals.

i also downloaded the software for haltech and adaptronic, but didnt seem to find my way into the really good stuff easily. seems like one of them wouldnt load with out owning the ecu first.

Good Answer. I'm leaning to the MS3 Pro. I'm wondering about installing just the board in a Stock ECU case & keeping everything intact.

Is there some reason to Not go this route?

I can easily add one or two wide-bands & MAP sensors.

It seems simple enough... How's your experience been with it?

The MS3Pro comes in its own plastic sealed case. Not too easy to rip apart and would likely void any warranty it would have.

You can set up a MS3X in a stock case and use stock type connectors. DIYAutotune.com has stock harness plug receivers. It's a DIY job. You would have to solder a board and jumpers to get the factory harness to work.

The MS3Pro comes with an 8ft harness. It is highly recommended to simply replace the whole harness to avoid any possible lurking issues. That being said, you can also repin the harness to the MS3Pro plugs. I think they sell patch harness lengths.

Then again, I'm a liar it looks like. I just did a search on DIYauto tune and found this.

https://www.diyautotune.com/product/ms3-pro-module/

You can then install this in a factory case and set it up that way.


If you want connector pinouts, go to Foxed.ca and look at the wiring schemetics and plug connector id tables. It's all there.

i thought about guttin an ecu and using the 850 board, it will be the cheapest route. i bought these to make a plug n play adapter for one of the cars i will use it with.

https://www.diyautotune.com/product/...ndenso-52-pin/


im doing every route you can imagine..
two cars gets the full 250 harness
my nissan v8 engine gets the 60 dollar ampseal connector on the end of it's factory harness
the turbo FC gets a patch harness made from the 60 dollar ampseal connector and the denso 52pin bob above.

Ok... I found the ECU diagram... It would be nice to have all the pins connected & Stock things doing "Their Thing" until I tell them other-wise or alter the function in software & re-purpose the wiring in the stock harness.

Why? Who Knows? Perhaps I want to use the Speed output data for the deleted power steering pump pressure to operate a rear wing when low speed cornering or open duct-work or tap the e-brake for auto drift...

The possibilities for other applications of deleted stock items like the AFM & other check connectors or warning lights or the entire air-vacuum system is a Proper Part of an Upgrade Path for me... I would guess that most don't care about that in their Preferences.

How many Pins do not get used when using the MS3?

Can you get to all the functions of the Stock ECU with the software & alter them to Suit "Whatever"?

I've built two Megasquirt systems for an FC, an MS2v3.0 and and MS3Xv3.0. I highly recommend the ECU if you have some electrical aptitude. If you buy a MS3Pro or a MS3X pre-assembled, it won’t be much more work than any other standalone, but the DIY boards are an undertaking. The confusion with Megasquirt is from it being so configurable. There is plenty of rotary-specific documentation, but the main manual (excellent) can be overwhelming because it lists basically EVERYTHING you could do with the ECU. The features and software for the MS3-based ECUs is hard to beat at any price.

I made a brand new harness for both of my ECUs. You COULD build a patch harness to plug into the stock wiring harness, but 50% of the benefit of going stand alone is ditching the cracked and brittle stock wiring harness. I have a good friend who builds lots of BMW patch harnesses for stock harness turbo-swapped cars. They have much higher quality wiring and are less baked from heat, so it works great for them. He actually just guts the stock ECU case and solders directly to the connector.
Building your own harness isn’t that challenging, you just have to be sure to check your work often and stay organized.

I've constructed more multi-pin cables & connectors than probably anyone here as an Audio Engineer... I'm very comfortable with complexity... Operating 64 inputs with side-chain monitoring & processing for multiple outputs is Mere Child's Play to me... to be Honest I prefer Proper Complexity.

So correct me if I'm wrong...

I can use all the Stock ECU pins in the Stock Harness?

Software allows me to use all the Stock ECU functions & change them?

My stock harness & engine function just fine right now (knock on wood), but I removed & blocked off the air control unit & cut the belt for the air pump when I put my RB exhaust on. I'd like to put it back on & get things working correctly again before removing more stuff & making a mess of things... I've done that once before & I'm looking to do things in a Smarter Fashion this time around.

im in the middle of it all, i want to keep the ability to throw the rtek back in the car.. but running the ms3 on the afm would be harder to setup then its worth. so think about what wires, they wil do and that ones that will say, there are a handful of pins for emissions you can opt out and re purpose
.

The speed output comes from the cruise control module, not the PCM. The PCM never sees a speed input in stock configuration. The speed sensitive power steering is not built into the factory PCM.

There are tons of threads on it, but the easiest place to get a speed signal is off the wire from the cluster to the cruise module on the driver side.

FC3S Pro v2.0:&nbsp Tips 'N Tricks - Cruise Control Speed Sensor Wire

https://www.rx7club.com/megasquirt-f...-ms3x-1093343/



As far as what doesn't get used with MS3PRO, that is entirely up to you. Normally the CAN bus wires, the extra 6-8 injector outputs, several PWM outputs, and a couple others are left over. Again, the ECU is 100% universal, so it has features that the rotary doesn't require.


As far as having the ECU perform 100% like stock, that's a big unnecessary undertaking. As long as you have the engine running efficiently, there is no reason to keep the AWS, EGR, and the Cold start functioning. The purge vavle for the EVAP system can be programmed in, which is a good idea.

After swapping the FC driven gear onto a FD VSS unit, you can get a vehicle speed output direct from the transmission (the FD unit will bolt right on) and send it to the ECU and also drive an electronic speedo.
If you're into that sort of thing.

I agree that many of the stock emissions features & the silly AWS systems can & will deleted.

As far as the Speed Sensor thing, I was talking about the Power Steering Switch in the ECU that drops the pressure as a function of speed... there's a transition point in there... or so I thought...

I could jump right in & white-board a good plan... Hope!

The Cruise Control Thing is Completely Different - but Wow! Traction Control! This where the Coolness Factor comes into play... Thank You for the Links!

As far as the Harness & adaptors... I have found that ANY Connections can & will induce noise & that Monkeying Around with an Old Harness can be Problematic...

That's why I'd prefer to go with Mounting the Board directly into the Stock ECU Case & doing all the connections in the ECU Box - without trying to remove the Good Condition Harness & Connectors in the Engine Bay... Besides savings in Time & $'s...

I'm Lucky to have an S4 that's Not Broken & Not Molested Yet... I'm Not in a Hurry & I Believe Good Planning at the Start will Help Ease Future Frustrations.

I would suggest making a small jumper harness using either an old ECU for the female connector or the DIYautotune connector linked above. You shouldn't have issues with having a second connection in the harnesses if everything is grounded and shielded properly.
As for rear VSS, it's very easy to get working. Front VSS requires some fab work OR an OEM ABS-equipped hub and ABS sensor. I also have front VSS working, but it gets noisy past about 60mph. Currently trying to solve that.

Thanks for the answers I needed... If Aaron Cake is Happily using one with success then I'd hang my hat on that...

Other Opinions or Options for an ECU Choice?

Nope. It bumps idle when it sees a pressure spike. That's all. You don't want to kill your car just by turning the wheel. OEMs have been using PS pressure switches for years to raise idle when steering wheel input is sensed. It only functions at idle too, so cruising will have no affect to the running strategy.

Think about it this way, if you have cruise control on, you don't want steering inputs to raise the rpm via the switch.

Perhaps you are correct, but I seem to remember drift guys complaining about the power steering assist transition point causing an annoying oscillation around 25 mph... or when the wheels would spin, the steering wheel would stiffen up ect... Then there was something about the steering computer thingy causing annoyance for something or other...

It's a vague memory from long ago... I'm planning on de-powering the Rack & junking the PS anyway, but I'm curious about what different functions the Factory Used that I might exploit for Other Novel Uses.

I would not get too hung up on what the factory PCM strategies are/were. There is no reason to exploit anything secret because there are no big secrets. A standalone PCM has all of that programmed in and you can set up whatever features you want.

The speed sensing PS was only on the S5 cars, I believe. It used input from the speedometer in the cluster to the cruise unit, and finally to the PS computer. The steering stiffening up when the wheels are spinning is normal. You want less assist at higher speeds, but drifting is a different animal.

Well... the Factory worked hard at silly things like cornering instead of just going straight... Why else bother with the DTSS thing at all? Can I make an active cam for that instead of a rubber bushing?

Awww... Just throw that Stuff Away... Mazda wasted all that effort just to make the car cost more, weigh more & be more complicated just to thwart my desires for perfection?

I thought that at least understanding what the factory did on the nitty-gritty, nit-picky things & why would be a good idea & I'm Curious what weird or mundane things already exist.

What Strangeness Exists? Rumor & Legend Drive Curious Vehicles!

They bothered because they were trying to follow the pack. Many other makers had some version of rear steering. The DTSS make the car unstable at speed and with wear, cause even larger problems. The FD has a track car style multi-link suspension with no active or passive rear toe. The Miata and RX8 also kept with the multilink rear suspension without any passive steering. The engineers tried something. It didn't work. They scrapped it. It was not about weight, cost, or complexity. It was about trying new things and setting a standard.


The rear suspension on the FC is not even that good from the beginning. They went from a live axle to the trailing arm system the FC uses. It has geometry issues when lowered and has a poor roll center stock. The arms also have a strange camber gain along with binding issues. That's why they changed after the FC.


The understanding is already there if you search long enough. The general consensus has been that the FC is a decent car, but definitely has its shortcomings. Ideally, you want a dual a-arm setup up front, with a better designed rear multilink.

Not saying the car can't handle well, because it has been demonstrated numerous times that it can, but the FC is an evolutionary step in Mazda's sports car development. From the FB to the FD, the Miata and even to the RX8. There are numerous refinements that make the car a argueably better car.

One of the many things that I dislike about the FC is the overreliance on the body CPU. They fail and cause all kinds of havoc. Back in the 80s, manufactures had not mastered a true BCM, like cars of today.

Thanks... That's real helpful... Other Perspectives are Valuable to me...

I wonder about strange things like having an electric OMP with it's own supply of lubricant instead either pre-mixing or stock using crank-case oil... I seem to remember the problem being one of the consumer would not be willing to do it reliably & too much of a pain...

The original idea was for the OMP Supply to be separate from the crankcase... Having electronic control & monitoring of the OMP System with some "Special Secret Sauce" in the Tank might be an improvement for reliability, performance & fault tolerance over either current system.

The AWS could also serve a similar & different function through a different part of the intake.

Like-wise, the Exhaust Port Air might be useful to help with Tuning by testing the Exhaust Temp & Wideband vs. Port Air Pressure for Timing & Fuel Tweaking without Detonation. If I go over Lean with a Port Air Pressure of X, then Stop the Timing/Fuel Advance...

Bells & Whistles can be Re-Tuned to play a different Song... I'm just trying to Decode & Settle an Old Score before embarking on Writing a New One.

This has been covered ad-nauseum in the single turbo threads. The short answer is, premix. The long answer is in this thread. Many engine builders agree on the same thing. Premix your engine to keep it lasting.

The oil injector is a small teeny hole that hits the middle of the apex and hopefully spreads out. It also leaves deposits from the crankcase oil. There are kits to draw from a separate tank, but you still only get oil right on the center of the seal.

With premix, the oil is mixed with the fuel charge and hits the whole apex seal and the side seals. Better engine life abounds.

https://www.rx7club.com/3rd-generati...-motor-887275/


Are you talking EGR port pressure? I do not think there is any tuning correlation to pressure there and mixture control. Now, using a UEGO and a EGT setup can be used for tuning, but it's not that cut and dried. The rear iron is typically hotter than the front and tuning timing based on EGT and lambda is not the most accurate way. The best way is with a knock sensing system and a dyno. I'm pulling a quote from another person. Name omitted to protect the innocent:


The big thing to remember is that a 13B doesn't make too much more power close to the knock threshold, vs a couple degrees back. If your power split between max timing and say 5 degrees back is less than 15-20 hp. Stay on the safe side and keep timing back.

You also should consider water or meth injection, if you go turbo.

Off Throttle Lube with Pre-Mix is a Loser... The separate tank system with electronic control is the way to go & maybe a very light premix... Adding OMP Injectors like RX-8 with 3 & a Custom Lube seems Far Superior to just dumping pre-mix in...

I was thinking more like using the EGR circuit for an in-car Popcorn Popper... Over The Top Switch for Exhaust Cut-Outs... AWS for wind-shield washer fluid injected manifold cooling-mist. The Shift Light Function for Exhaust Tip Flames & other such Non-Sensical Flights of Rotary Fantasy.

The Link simply confirmed what I'd already thought... Thanks! ;)

the speed input goes to the power steering computer, not the engine computer.

It's pretty common to squirt a little fuel (coincidentally premix as well) on decel to combat the no lube on decel argument. No one is counting MPG's on a rotary.

Right.... What's the power steering computer do? Can I used it for something when I delete the PS setup for a manual rack? WTF is the extra computer thingy doing? Why did the factory bother with it? Can I use it for Ground Control Effects? Turn the Headlights with the Steering? or little Wing-Thingies? Control my LED wheel lights for color changes?

The simple answer to your question is probably not.

When you delete PS, you remove the switches that tell it to do it's job. That is all they are. There is not really many inputs that it relys on. Also, you said your car is an S4. I'm pretty sure you do not have speed sensitive steering or a PS computer.

If you say so... Maybe it's just a warning light...

I'm pretty sure the EGR-Popcorn Popper will work though... Doing Flame-Thrower Donuts to make Jiffy Pop seems appropriately Obscure Enough to be Popular... The AC cooling unit just didn't seem efficient enough to make a good Gelato... Maybe an Espresso Machine Hook Up? That's pretty do-able...

The Technical Papers from the Power Steering section here:

http://foxed.ca/rx7manual/manuals/Tr...ing_System.pdf

Actually have some great detail about how it all works & is probably easily adapted for various uses related to Engine Speed/Vehicle Speed/Steering Angle and anything else you wanted to use it for...

Seemed completely Brilliant use of a Variable Hydraulic Torque Arm... Someone could totally use the Steering Computer for something other than an ash-tray or spud-gun target... ;)

Right, but it begs the question. Why?

I have honestly checked your posted threads you have made and you have had some rather crazy ideas over the years. Good for you that you are curious and want to experiment. I have no issues with that, but the it still begs the question as to why.

I look at any modification or service item like this. What will this accomplish and will it make a difference while being simple and reliable. Bastardizing stock modules and repurposing them seems cool and all, but it still adds complexity and an unneeded element. This is my personal opinion. If there was a way to really get something useful out of these modules, cool. But you still are trying to accomplish a task with a primitive piece of equipment that often times a proper standalone engine management system can handle. And do so more elegantly.

Sure... I get your point & Rightly So. Why? Why Not use Imagination to Innovate beyond the Simple & Easy. Why would someone take a telephone or a record player & teach it to be smart? Why does a Dog need a GPS Collar? Why Heat Food with a Radar Dish?

Why would I want a movie camera on a Police Officer? Who Needs A Lawyer anyway... I Know I'm Right so I'll Win... I'll keep paying for an Upside-down house because Bankruptcy is Dis-honorable & My Ego is More Important than My Family.

I'll Tolerate every Injustice Done to Others as long as my Ivory Tower has a Manicured Lawn & Rambo on Speed Dial...

Yeah... You're right... It's Silly to try to understand what you actually have & how it all works... No One Cares about any of that... It's Too Hard to Think when some one else will do it for me all the time... I need to go write a list of all the people I might have possibly offended by speaking my mind all these years... The Thought-Police have Pulled My Permit...

Woah dude, take a step back. I'm not trying to hate bash your ideas, on the contrary, I have been replying and trying to help give you insight.

You originally asked about upgrade options for just the stock PCM. It spiraled into where we are now. No need to drag a political strawman into this discussion. This thread was about options and upgrades to your FC.

You want to bring it down to this level, take it to the lounge.

You originally posted that you wanted to keep this as a street car, then it spiraled into using the PS computer to actuate active aero. That's cool and all, but don't act like an ass when I tell you that I PERSONALLY do not see the reason or benefit to monkey around with aging controllers, when you can install a single controller or a couple ad-ons to do all that you desire.

You wanted opinions and you've gotten a few. I come onto the forum to research and help and learn.

If I wanted a political jab, or a sarcastic comment about how much I did or did not want to learn and experience, I would have my father in law yell at me about how "Trump will fix America."

How about instead of brainstorming, you just try these things out..all the information is out there after all...you dont need everyones opinion or approval...i hope.


Also, judging by your last couple of posts, you get butthurt pretty fast. Calm down, its the internet. You can turn it off at any moment instead of accusing everyone that they are oppressing you

Someone begged the ? of Why Bother... It's a Legitimate Question. Same as "What difference does it make?"

It's a simple comparison & perhaps "Rotary Politics" does indeed Mirror our upside down current reality.

Why would Aaron Cake take on an RX5 Cosmo?

It's a Simple Answer - We Chose to Go Rotary - Not because it is Easy... But Because It Is Hard!

Some might not be very amused by my comparative analysis because their In-Laws Rant & Rave & Curse about Some Person or Other should be Jailed or what-not... That's strictly a personal problem & beyond my purvue in this Forum...

I'm just not very receptive to Promoting Ignorance or Just Throwing Things Away without understanding what I have & where I want to end up.

I think History & Perspective are Important & forgetting what you started out with mostly leads to faulty conclusions about your own identity. Might as well have Herbert Hoover organizing the Gay Pride Parade to take a Long March off a Short Pier.

I don't get Offended... Quite the Opposite... I get quite excited when someone asks me "Why Bother"... I believe It Is Important & Worthy of Discussion. Even if some Kindergarten Passive-Aggressive Displays are Required to make a Point against ignorance & mental laziness.

Promoting ignorance? We have came in here and gave our opinions on a good starting point. Your original post related to a stock replacement PCM. That is where this started. You originally said you wanted a street car.

It's tough for us to guess where you want to end up when you flippantly start talking about repurposing controllers and ports to make ice cream and popcorn. This is far outside usual experimentation and I feel you are not taking this seriously. Sure, you can future proof and come up with many different ways to do something, but "just throwing things away" has nothing to do with it. The RX7 stock controllers are very primitive. You can delete them and use a single controller to accomplish what Mazda took 5 controllers to do.

It's just an RX7. Nothing more. This is not the Starship Enterprise. We are not discovering the cure to cancer in our cars. We are fixing them up to enjoy them and drive them. If you want to do something bold and crazy, go for it. I'm not stopping you.

That attitude is not required at all. It's disrespectful of those who have been replying to you. You have no idea what I do for a living, or what I spend my time learning and researching. There is no point to be made against "mental laziness". This isn't a TedTalk, it's a thread on a website.

Asking the question, "why bother" in this case relates to the fact that you have been all over the map with your plans and ideas from the beginning, with no clear goal. There is no cookie cutter answer that will satisfy you, obviously, but when you want to experiment with controllers that have no programming ability and are simple I/O boxes, it does beg the question as to why. If something can be made of it, great!, but you could be more constructive with your time and get back to the original task at hand.

You wanted to upgrade to a standalone. A quality standalone can do all of the things you want to do and with the ability to program them. There, you can do the wild active aero, auto drift, popcorn maker, steering actuated headlamps, and more. That should make a well rounded street car for you.

I agree... What Exactly does an ECU upgrade do when installed in a Stock Vehicle? Specifically, all the Stock Equipment. What has to be deleted? What factory systems are abandoned & which ones have to be modified?

There are many aspects of the Stock ECU & wiring an Upgrade Board into a Stock ECU Box & getting things sorted out. Especially when I'm not planning on changing the harness out for a new one.

Perhaps I should have posted this in the ECU Forum - for that I Apologize.

My thinking was that my question seems quite Basic in Nature & would have a Broader Appeal to Forum Members in the 2nd Gen Section.

I have the Time, Patience & Opportunity to make "Good Choices". If I was a "Know It All" I wouldn't bother to ask questions & make silly propositions - on the Contrary, I Desire Knowledge & Opinions from Others - I know what I think already...

I can be Serious & Silly... Lighten Up a Little... I'd like to at least provide something thought provoking for all the trouble other members go through just to read my "Drivel".

There will be an Adaptronic Modular FC3S PNP ecu available in the future;

https://blog.turbosource.com/2016/07...lar-unveiling/

This would be by far the most advanced PNP unit for your car.

Very valid questions.


It's a free forum, man. Post away.



If you can do something truly unique and different, I'm all ears and excited to see something new. I do get tired of seeing the same hacked up drift builds here, so something different may be cool.

I remember reading on Aaron's website about his PC-based room/home controller. It had the power to adjust lights, run fans, music, etc. I personally never had the drive, nor ambition to do that, but I respected his project. I should have used the same lens with your project. Even if I personally see it as a waste of time to reverse engineer a controller, that doesn't mean that you can do something useful with it.

I generally take things far too seriously, and I know that I probably should take a step back. I look at things in a far too "black and white" way. In my job, I get burned out from all of the experiments and case studies that I get forced to do, and I diagnose cars for a living. I usually am stuck deep inside a euro car of some kind, trying to figure out what the hell it's thinking and trying to do.

After researching all day just to create a test plan to diagnose a fiber optic network on a BMW, or diagnose a faulty CAN bus on a Mercedes; I usually pack it in when I get home to my car and try to keep things simple. With my project, I approached it as a car that I want reliable and simple. Simply because I spend so much time going over theory and operation on controllers all day, I couldn't care less about what Mazda was thinking with their aging controllers. The logic levels of them are so low that I see no real use for them outside their intended function.

That being said, no hard feelings. I felt like you started off with a very valid question, and continued to continue valid lines of thought. I just got a little derailed at the gelato and popcorn bit. I couldn't tell if you were serious or not, since the internet is a rather strange place.

If it were my car, which it's not, I would approach your objectives from a different angle. Instead of thinking about expansion now, look at the whole scope of the project and come up with an end goal. That way you don't get fussy over contingency. For example, you can delete the PS computer, the stock ECU, and whatever superfluous sensor the stock PCM relies on. This being the MAF, boost sensor (even NAs get a "boost sensor"), the AWS, the thermowax (a proper PCM can control the BAC well enough to maintain cold idle), and maybe a few I missed.

Some of the things to keep that could be useful are the steering angle input from the column to the PS CPU. That can be used as a directional yaw input, maybe for traction control, and you can also use the output from the cluster for a speed input.

These are at least two things that are very handy if implemented properly. Trying to modify a PS controller to turn on headlamps and stuff is an exercise in futility. YOu cant necessarily program the points of activation and are stuck with the onboard logic, but you can still try and figure something out. The tech manuals are out there.

Wow! That is Very Helpful & in-line with my thoughts. Thank You.

The Adaptronics Debut seems to be Right Place & Right Time... I have the "Perfect Test Vehicle" for a Stock to "Whatever" Project.

An Un-molested & Functional '88 S4 GTU is a Good Place to Start at... I'm open to possibilities.

I'm a Willing Guinea Pig... I've hacked my way through this process once before & have a chance to do it over again correctly.

Perhaps Adaptronic has a need for a Proper Test Vehicle? I will Gladly Volunteer.

While we wait... Has anyone fabricated a Grill & Pressure-cooker that hooks up to the exhaust tips? A temp sensor & cruise control cross-wire could give a good temp control & an extra high-rise exhaust stack from the add-on Grill Box might mitigate some of the Terror.

It might be popular at Cruise-ins & Tailgating activities.

My Father was something of a Practical Joker around his office back in the Day... In Light of My Lack of Complete Seriousness I'd recommend placing some Jiffy-Pop Popcorn on Someone Else's exhaust manifolds or pipes for some Proper Levity...

Outside the Engine Bay & under the car preferably... Unless someone is particularly Nasty... Then they get the Engine Bay Popcorn Bomb... Have a Fire Extinguisher HANDY... & a shop vac... The Horror! ;)

Try this: :P

I am considering getting that same PCM. The modular nature is a big plus.

This? Adaptronic Select Mazda RX-7 ECU

That is not the modular, but a fine ECU for non popcorn maker/rocket launcher/ejector seat needs. I use that in my own car.

This is why I'm trying to ask the correct questions...

Let me try again...

Is there an ECU that can "Plug right in" Stock & Grow with Me on a Varied Upgrade Path?

I can wire one into a stock box or not... Extra ports & modern interfaces are a good thing to have of course... & the Stock ECU Case may be a step backwards. Installing a New connector on the old harness is subject to the patience & skill level of the Technician & Not recommended by Me...

Even though I've plenty experience in this department in a different profession... The oxidation state of the old harness makes this process very tedious to complete properly under the Best Conditions.

A Jumper Connector from the New ECU Box to the Old Harness would seem to be Less Prone to Problems & Failures than the other options. The Old Harness Connector can be inspected and the contacts properly cleaned & some pro-active care can keep that old connection solid & less prone to noise or glitchy interference or creeping corrosion or moisture problems.

The cost of the Jumper Harness would be worth probably $200 pre-made, but you'll easily save that much in Time & Effort doing your own work - possibly more than once or twice to get it correct...

I used to do large multipin connectors as a Tag Team with my Elder Mentor acting as a Surgeon & myself as the Assisting Nurse in a Delicate Operation. Crimp Pins are Full of Fail on an Old Oxidized Wire... Doing this operation on the floor-board of your car is a recipe for disaster even for an expert.

You would need to "somehow" remove the corrosion around every individual strand of the twisted wire... Acid Flux not-withstanding... Soldering will fail miserably. Then there's heat shrink or potting the connector with epoxy or hot glue to keep the solder joints from stress cracking under vibration... Until it does... Then What? My God! Shoot Me Dead Now!

A New ECU Box & Short Jumper Cable for the Old Harness Connection would seem to be the Winning Move for a Product to be Easy & Reliable without the Head Aches of the other Methods.

The short answer is, there really is not a "plug in unit" that is for the NA RX7.

You can build one using megasquirt components, or you can buy an FD PowerFC with a Banzai jumper harness like this one.

APEXi Power FC Adapter Kit (86-88 RX-7)

If you are that concerned about oxidation in the harness connectors, which are usually in good condition since they are in the car, then look at wiring in a custom loom. I've torn apart quite a few cars in various makes and models. The PCM connectors that live inside the car are often in great shape with like-new wires. Once you get into the engine bay, the story changes. It's really easy to pull the engine loom through the bay to work on it.

You drop the blower case out and then pull the engine loom through the firewall and crimp the wires while working on the fender. The third connector inside the car is a bit tricky, but it's only one connector. I have never had a problem repinning a connector on a car where the connectors were inside the car. Under the hood and body are a different story.

Good Answer... It depends on the conditions... I always thought the Stock harness & connectors were a strong point quality-wise.

I remember leaving the sun-roof open too many times while at the beach bar & getting showered more than once inside... but the Harness & ECU from my now-deceased base model S4 was in decent shape - though there was some corrosion on the case.

I'll err on the side of caution when I make a recommendation & your experience demonstrates that it "Doesn't have to be a Nightmare" & I'm just telling Scary Stories about the Boogey-Man to Scare Little Rotards when "It's Really Not So Bad" That's a Good Balance...

The Conditions Matter as well as Competence.

I looked at the PowerFC link with the adaptor & the actual ECU. How is it? It looked like what I'm searching for, but what's your experience?

The Price is in the ball park I guess... about the same as any other unless it's a kit-type...

Moding a Trailing Coil & Ignitor? I've got a few spares in the bone yard...

I personally do not have experience with the PowerFC. I know that many other users have loads of experience and really like them. The ECU is a bit outdated, since it was developed 10+ years ago. I know Howard Coleman ran one on his 500+WHP FD for a long time and liked it. It's a reliable and capable PCM, based on what other users seem to have been accomplishing.With a Datalogit, it's a well rounded unit that has aged rather gracefully. The PowerFC forum is where you would want to ask the heavy lifting questions. I did look at the PowerFC, but I wanted to replace my whole harness and go with a newer style of controller.

I just found this on a different post in the forum. Just stumbled into it, really...

Adaptronic Select Mazda RX-7 ECU


This is the thread that I found it in.

https://www.rx7club.com/single-turbo.../#post12045548