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2007 STi Satin White Pearl
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Discussion Starter · #1 ·
Ok guys, so I'm finally ready to get an EMS after dropping in the built 257/251 hybrid. problem is there are so many options and I just have absolutely no idea what to do. I'm hoping for something relatively easy install-wise, and I'd like to try and tune it myself if possible.

I'm sure anyone looking at this knows the options out there, so please give me some input. I'm trying to stay away from Hydra mostly due to cost, but if its infinitely better than the others I'll suck it up. I'm mostly leaning toward the AEM EMS-4 right now, since it seems to be the best bang for the buck, but I'd also like some info on megasquirts. I'm not opposed to doing a wrx or sti ecu, but they seem to be the most difficult to do and I'm not even sure it would work with my SOHC heads.

Help me out here guys, I don't want to drop big money on something like this and regret it later.
 

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the AEM software is very intuitive, and easy to navigate. Tons of upgrades from MAP based tuning, integration with a wideband, integration with water/meth, all easily accomplished. Plus, great tech support and the platform is very stable

cant offer any help with megasquirt sorry
 

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2007 STi Satin White Pearl
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Discussion Starter · #3 ·
Thanks for the input! Ease of software seems to be the biggest selling point on AEM. Any insight as to whether or not it is worth it to get the series 2 over the ems-4? From my understanding the ems-4 is the same thing, just smaller and for 4 cylinder applications only, which obviously doesn't hurt my feelings any lol.
 

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EMS-4 is a universal ecu. Uses the same architecture as the Series 2, but does not have a plug and play harness. As such you'll have to wire in all your sensors, do sensor calibrations, creat your own base map to start the car. Will be much more upfront work, but it does have a lower entry price

The Series2 is plug and play for the 04-07 STi, so far more integrated and easy to setup and start using.
 

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Discussion Starter · #5 ·
PnP doesn't really affect me, from what I've gathered there is no PnP EMS for an 04 RS, so no matter what i get, I'll have to do some wire merging
 

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2001 A.W. L
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13,249 Posts
I would suggest getting a local tuner to at least start you off with a safe tune. Then start modifying it on your own. This way at least you know you have a safe tune to go back to if issues arise.
 

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97 L, 13 WRX
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1,537 Posts
I run a Megasquirt 3.

I think if you are just starting out learning how to tune. Don't do it on a turbocharged car. Especially with software you haven't ever used.

I would recommend wiring in a WRX ECU because it will work with your heads. It may require a couple modifications due to IAC, throttle body, intake manifold differences. It will be cheaper to purchase and you will be able to get it professionally tuned for less than $500 and there are quite a few tuners who would be able to.
 

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'98, RS-T
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534 Posts
There are some DIY posts on RS25 that you could follow along and see if you are up to the MegaSquirt route. As for tuning it yourself - just open the wastegate and the engine won't make any boost. Once you have a solid NA tune, add boost in slow increments and log your results. A wideband is a must.
 

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Discussion Starter · #10 ·
Ok I've now decided to not tune myself, I'd just rather have it professionally dyno tuned so that theres no more issues out of it. I don't see how a wrx ecu would work considering wrx's are dohc and mine is sohc. explain?
 

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97 L, 13 WRX
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Because they both use the same crank and cam sensors, and the same trigger wheels. It doesn't effect the ECU if you have single or dual cam.

I'm not sure what your ECU plug looks like, but I'm thinking it's the same as a 01 RS. That means you will have some work cut out rewiring and finding out how to wire in a WRX ECU.
 

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Just go with a hydra. They really aren't that pricey if you get them ore-owned. I got my hydra ems for less than $500. It was originally for a 2005 STi. I have a 2000 RS. I sent the EMS back to hydra, they did hardware changes to make it compatible for my RS. I was charged $150. They also tested my unit to make sure it was in working condition. I then payed element tuning $325 to make me a pnp harness (totally optional, but I don't like tapping into a crapload of wires). And because the hydra unit I bought was originally purchased from element tuning, Phil will give me tech support for $150 including a start up map with mods really close to what I will be running, so then my tuner can make slight adjustments to the tune as needed. Total cost to have my car running perfect.....under 1K, result......PRICELESS!
Lol, I couldn't resist.
 

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if you've now decided you're going to pay to have it tuned, spend the time and energy shopping for the tuner, not the ecu

if you've never tuned any of these type of ecu's before, it would pay for you to take a class like EFI101, or something similar
 

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95 L, 96 OUTBACK
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Go with a stand alone. I have no experience with hydra or AEM because I am using MS2.


If you use the stock WRX ecu you are stuck with that engine. If you want to put say a FA/FB20 when they get cheaper in the next few years you will have to change your setup. You can put a older engine in that has different crank and cam triggers too.


MegaManual Index
Megasquirt Product Comparison

It isnt that difficult to build or tune. There are programs that take your datalog and makes direct changes to the VE table so you hit target AFR. You can get a fast tune that way. IMO best bang for buck.
 

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2007 STi Satin White Pearl
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Discussion Starter · #20 ·
Thats all really good info thanks for the links! I did find it weird that the MS3 is obviously the most capable, yet it doesn't support water/meth injection like the MS2 does, which that is something I had intended on doing. It does support nitrous though which is cool.

So basically what you're saying is, I can install the MS, run it for a little bit and get a datalog, then use the software to do kind of an automatic base map tune for it to build off of?
 
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