I was just about to buy the sprint re when I saw the ms3. What I wanted to know is the ms3 better then the sprint re, can I use the stock s4 Tps on ms3, are there temp sensors that I can use that I don't have to tap new holes. And one last thing does the ms3 support self tunning software. Thanks I'm on the road and used the android app to post this

 

Okay was able to do a little bit of research and this ms3+msx looks awesome. From sd date logging and auto tuning to shadow dash I'm sold. I just need to know can I still use Aaron wiring diagram on the ms3?

 

Talking about this one.

 

Yes you can use all stock sensors. But Gm ones you don't need to change bias resistors to make them read right. If you are doing your own tuning doesn't really matter what ecu you use. Use the one that you think you can get the most support for. Because when issue a rise it is much easier to fix with some help.

 

I see, I guess I'll be going with gm sensors. I have a tuner I just need to get it going to drive to his shop. Also still trying to fine a diagram for the rotory engine and just need someone to confirm if I can use Aaron diagram on the ms3 thanks

 

If you want to use sequential injection your spark and injector wires will be a little different. They will hook to the ms3x card instead of the main board.How to MegaSquirt your FC RX-7 They have some info here on there site.

 

Well, the short answer is that the MS3 w/MS3X is better than the Sprint RE. The fact is that the MS3 is far more configurable and offers many more features out of the box. And will continue to improve on a regular basis as new firmware is released.

You can use the stock S4 TPS, but be aware it is a quarter range TPS so there are some quirks when tuning. For example, it is difficult to use the TPS to decide when to run open vs. closed loop because the TPS reads 100% at only about 1/4 throttle. It will also limit some of the versatility of things like throttle dependant boost control. It's not the end of the world, but if you have the option to run a proper full range TPS (really not that hard to adapt a Ford TPS to the 2nd gen throttle body) then you should do it.

As for sensors, you can use the stock sensors but why? They are old, hard to find, and read odd values. You'll also have to change the sensor calibration on the MS, and remember to do so when/if you change firmware. The GM sensors are cheap, new, and everywhere. A little short term pain in tapping (takes maybe half an hour to do both sensor holes) for long term gain.

Parts of my wiring diagram will be correct, but parts won't be. All the basic sensors are the same for all the MS versions (TPS, CLT, IAT, etc.) as is the relay, fuse box, grounds and basic wiring. However the MS3 injector, ignition, CAS and I/O wiring is different. Until I update my writeup for MS3x, DIYAutoTune has a good install article that covers all the MS3x specific stuff:

How to MegaSquirt your FC RX-7

 

To make a statement that the MS3 is better than the Haltech Sprint RE is incorrect,
Haltech has a lot more experience than MS and a large track record to back it, from the standpoint of marketing features the MS3 has lots unit to unit, haltech Sprint RE has everything you need and is setup for the engine no setup issues and it is back by their years of experience.
Word to the wise, look at what ECUs are in the cars that win and drive well!
You don’t want an ECU that may damage your REX due to Bugs in its software.

 

It was that same "haltech experience" that allowed ignition wander on the trailing and allowed negative split under full load that steered me off of haltech several years ago.

 

Thanks Aaron, just a quick question do you have a eta on your updated write up? I can easily follow a visual diagram but have a hard time following text instructions on diagram. Have a hard time visualizing the text instructions

 

Sorry, but to say that me making a statement that the MS3 is better than the Sprint RE is incorrect is in itself incorrect.

The Sprint RE is good ECU, but it is a very basic ECU. For example, I'm checking the manual right now and it doesn't seem to support an idle valve. I could be wrong, but I see no reference to it in the manual. To me that's a show stopper. But again, that lack of one feature does not make it a bad ECU because if we were to do a feature comparison between the MS3 and frankly any Haltech, the Haltech would lose by orders of magnitude.

I do find it interesting you mention software bugs in the MegaSquirt. In all the years I have been building, modding, installing and tuning 'Squirts, I can only think of one odd software quirk I've experienced. Now keep in mind I've been involved in the 'Squirt since the days of the 2.2 board running MS1 on B&G firmware, before MSnSE was really even available. This bug would cause trailing ignition to go away when a user entered the boost control screens in MegaTune. I never bothered to investigate it much but I'm guessing it had something to do with how the trailing split and boost tables were paged in and out of memory, as the MS1 CPU was VERY limited. Trailing would come back after entering the timing table. A curious bug, but hardly earth shattering and it only existed in one particular version of MSnSE (29Y I think). So I'm curious, what specific bugs have you encountered in the MegaSquirt that has damaged your RX-7?

I'd also like to point out that it isn't really the ECU, but the talent of the tuner which makes a car drive well. Given any ECU that isn't stone aged (ie. excluding Microtech), a good tuner can make the car drive better than OEM if that tuner knows what they are doing and are familiar with the features of the ECU.

I also don't think I need to point out that drag racing as shown in your video is probably the least ever relevant example when comparing ECUs, as even the lowest resolution poorly featured ECU will supply fuel and spark suitable for WOT drag runs. Tuning WOT is dreadfully easy, tuning for the 99% of other driving is where the skill lies.

I honestly don't have an ETA. I have enough pictures to document modding the MS3X harness and setting up the ECU, but I don't have detailed pictures of the injector wiring. I'll be able to get these pictures as I wire up the MS3-Pro on my Cosmo, so I think we're good in that respect (though my intake manifold arrangement is a bit non-standard). Maybe within a few months if time allows.

 

The Sprint RE does not do any closed loop self tuning for gas mileage purposes.