I have a 90 with a Jackson Racing kit with the boost upgrade kit and a J&S controlling timing retard. I have read about MS for a while and would like to make the switch as I plan to build a custom turbo system down the road a ways, but I have a few questions about it.

1) Budget - I know the cost of the MS, Wideband, Sensors, Wiring. But will I need different injectors or anything else with my current setup? I imagine the upgraded fuel pump that came with the boost upgrade kit will be sufficient, so what would a realistic total budget be if I build everything myself? I have a crappy laptop already as well.

2) Fuel and Spark Maps. This is where I dont know much at all. The car is my daily driver and I realize there is ALOT of tuning and tweeking involved with MS, but is there a base set of maps that will at least get me running to make it to work on Monday if in a pinch? Will the maps posted for turbo setups work for supercharged as well.

3) Water Injection - I may be interested in setting this up down the road as well, and I read that MS will control an injection system. Is that feature park of the build or is it an add on in the prototype area?

4) Just want to make sure I am on the right track here. Once the MS is in the car and setup I would really have no use for the J&S correct? If I could sell that to offset the cost of the MS swap that would make this a real possibility.

5) Power Increase with just MS. It would make sense to me that I could expect to see some increase in performance just by getting the MS in the car and dialed with my current setup as opposed to running fuel and spark bandaids to try to make the car run under boost. Would this be a correct assumption?


I appreciate the help. I obviously have a lot of reading and research of ahead of me, but I wanted to nail down a few specifics by asking for advice from some of the people who have been there done that. Take care.

-Hank

 

You will need different injectors, unless you keep the rising rate regulator. Keeping it would add another variable, and be a bad idea. Larger injectors can be had for a few hundred.

Should get you close, but personally the wiring took much longer initially. As long as you are soft on the spark and have extra fuel, you have little chance of hurting things.

Not built in, check out http://megasquirt.sourceforge.net/extra/index.html

Sell it. MS can use a knock sensor with a little work.


Yup. Ditching the AFM while NA is said to be worth 10hp, probably more if you are FI. Plan on some dyno time.

 

I agree with everything above, but big injectors can be had used for as little as $50, plus cleaning, $60.

 

10-15hp gain on a 90-93 would probably be expected one you remove the MAF.

 

Great Guys. Thanks for the input. I'll keep reading up and budgeting and see what happens. I just wanted to make sure that I am on track with my logic and understanding so far.

Also, it seems that the 3.0 board is recommended, is this the correct one to get or will the 2.2 work ok for this application. Every little bit helps as far as keeping costs down. Thanks again.

 

I would get the 3.0 board because it has better build in circuit protections. Also the prototype area on the board will be needed for adding features later.

 

3.0 it is then.

Alright. This may be the mother of all dumb questions, but I'll ask anyway. Is it possible/safe to remove the supercharger belt on my car and drive the car? I dont see why this would hurt anything other than the fact that the engine would have to suck air throw the blower assembly. Plus I guess I would not have power steering since it shares the belt, but no worries.

Would there be any risk of damage in doing this? The reason I ask is because I could run the car not on boost for a while and sell my J&S knock sensor to fund the megasquirt conversion. The MS itself isnt too bad but the addition of the wideband which seems to be an absolute requirement is a killer. I could buy and build the MS unit. Then remove the J&S and and cruise around essentially NA and use the money to buy the LC-1 and injectors, then swap in the MS and put the belt back on. Does this seem logical? If that is a retarted idea, please let me know.

The whole idea of Megasquirt is appealing to me, so I would really like to be able to pull this off. The car runs OK now, but does suffer from lean tip in hesitation and I know it isnt running optimally at all. When it first starts, it's hunts for idle and it does stall sometimes at lights until it gets fully warmed up. If I could have the experience of going full standalone, the ability to tune the car myself, and get a more reliable, better running setup in the end, I would be pumped. Plus I figure there is some untapped power that will be able to be extracted with proper management.

Thanks again.

 

Here is a little trick you can do on the supercharger: Look at the bypass valve on the throttle body assy. take some zipties, and hold the bypass valve in the open position. this will cause the supercharger to make 0-PSI. I did this on my '94 when i went on road trips to help with gas mileage.

If you have trouble locating it, have someone start the car while you look at it. at idle, the bypass valve will be open (vacum operated). that way you can see what you need to tie up, and where.

That way you don't lose P/S and A/C by removing your belt

 

Makes sense. I certainly didn't think of that. I appreciate the input. So I assume it will not cause any problems to run the car like this for a few weeks if necessary. I don't see why it would, but just need to be sure. I work and go to school relatively close by, so it wont be many miles overall.

 

I didn't have any problems running it like this for a 3 week road trip. It's basicly stock at this point, but with an extra 20# of dead weight on the engine, lol

BTW, to answer your budget question, I'm doing some virtual shopping now, just waiting for another job before I can actually buy. but at least it gives me a lot of time to read. My set up will be MS-I PCB3, relay board, stim, cable/wiring, 440cc injectors, sensors, and wideband should be less than $700. I'll probably add a new fuel pump just because the one in the car has about 210k miles on it. ~$60

 

Thanks again Miaturbo. I'll just wire the bypass open when the time comes. That way I can sell the J&S and not worry about timing control until the MS is in.

Now I just need to keep reading up on the whole process.

I guess its time to start the serious research. I'm sure I'll have some more questions to come.

 

Well, I am officially going to be a megasquirt convert. I bought an MS tonight on fleabay. It's the 2.2 board which I hope will be ok, but it was a good deal so I went for it. It came with a stim, wiring harness, and a serial cable all prof. assembled and what not. I was looking forward to building it myself, but oh well, I'm sure wiring it all in will be enough of a project. Is the 2.2 board going to be ok? I could always sell it and get an unassembled 3.0 for the same price if it would really be worth the hassle. What do you guys think. Thanks

 

If you got a good deal on all of it I wouldnt e too worried about it being a 2.2. As long as you can run MSnSE then you will be good to go (OH btw, you can). Welcome aboard, you won't regret it! Also, get on rx7club.com and look for some cheap injectors, and save up for a lc1 off ebay. Thats all you need for complete control.

Brian

 

Excellent news. I got the MS, harness, Stim, and Cable for $225. I figure thats not too bad at all and it hasnt been used or anything.

Ah, Rxclub. That was my old site before this one. I love my miata, but I miss my 93 touring edition 7.

I cant wait to get started with the megasquirt stuff. I just need to sell my J&S knock sensor and pick up the Lc-1 and injectors and then the fun begins I guess.

 

I could use some help with fuel injector selection if anyone has suggestions. I plan to run the MS on the miata with the supercharger for a while and then build a DIY turbo setup. I would like to end up with 250+ RWHP when all is said and done. What size injectors would I need to get now that would work with my "down the road" horsepower goals. I looked into some of the 550 RX7 injectors listed in the FAQ DIY turbo thread and got a quote of $103 shipped from someone on RX7club. $220 if I wanted them cleaned and balanced by RC.

Also, I was told that the part number listed on the FAQ thread does not match the description.
89-91 RX-7 Turbo (550cc - purple top) - #195500-2020
The guy said that that part number is for a red top injector of some sort. Can anyone confirm the correct part number?

I really want/need to spend as little as possible right now, but I dont really want to have to buy things twice. What would be my best bang for the buck injector option that would fit my needs. Thanks again for the help.

 

IMO, the best bang for the buck for your 250 rwhp would be those RX7 injectors or maybe some black top supra injectors. Or even cheaper, you could pick up some DSM (440cc I believe) for fairly cheap and then pick up a resistor pack off of a honda to set them up as high impedence. I was in the same boat as you for my MSnS + custom supercharger project, so I just picked up to 326cc B2600 injectors for 10 bucks off ebay! I couldn't pass up the price and later on down the line I may need to install an AFPR depending on my power needs.

 

I bought red 550s myself because I couldnt find any of the P&P ones. The pintle caps were a tad too wide so I just dremeled them to fit and then polished them a bit. As for the connectors on the harness being the wrong kind I just bought a injector clip kit on ebay for like $10 and cut off the old ones and crimped on the new ones. Works like a charm, took me about 30minutes for the entire install and clip change.

 

If you buy injectors from that guy you can have them cleaned and flowed yourself for $60 at cleaninjectors.com and a few other places. Save you $40 right there.

 

Good to know. Thanks for the suggestions. I'll keep searching and try to find a good deal on injectors and an LC-1.

Sensors? Is it recommended to use the stock sensors with MS or do I need the GM ones on DIYautotune? I know at the beginning of the year when I bought the car, I looked into megasquirt and most people used GM sensors, but now I have read that it is possible to use the stock ones. What is the opinion on this. Stock is cheaper, so if that works, bonus points.

What about base maps? This is where I have no idea what going on. Is there a base set of spark and fuel maps that would work well with the supercharger to get me up and running to start the fine tuning process once everything comes together?

 

You'll need at least a IAT sensor since you will be removing the stock AFM You can do what I did with it though. Instead of running a new wire just wire it into the original signal wire from the AFM harness; it is the green wire.