Project EVO IX Part 8: Tuning for AEM water injection

Project EVO IX Part 8: Tuning for AEM Water Injection

By Mike Kojima

When we last left our project we had just installed some Cosworth M2 cams and had tuned around that with excellent results.  Some time ago we had installed an AEM water injection system and warning monitor system and had been running the water, mostly just for thermal control when running hard.

You can read about our install here: Part one, Part Two,  Part Three

Read more about Project EVO IX Here!

Project EVO IX Part 8: Tuning for AEM Water Injection
 Here is our latest and greatest AEM water injection system mounted in our trunk.  Read the back links to get all the details of how we got to this point.

We knew to get best results we would have to tune our ECU to take advantage of the detonation suppression capabilities of water and to nullify the water's quenching properties which reduce power.  At this time we also wanted to upgrade our ECU to take advantage of some of the latest developments in stock EVO ECU tuning that have transpired.

To get our car ready we first wanted to have better boost control.  The stock boost control solenoid is a two port type that works by bleeding off boost pressure that is being sent to the stock wastegate actuator.  This fools it to stay closed above the native actuator spring pressure until the solenoid's flow capacity is over run which then allows the wastegate to open.  This simple system can be tuned via the ECU and works ok up to the low 20's in psi of boost pressure.  The trouble is that the two port solenoid starts to get iffy above this boost level. Since we wanted to run in the high 20's for this next round of tuning we had to get something else.

Project EVO IX Part 8: Tuning for AEM Water Injection
The stock gold color two port solenoid is shown up on top and the 3 port solenoid is the black unit on the bottom.  We used Hose Techniques high temp silicone vacuum lines to plumb the solenoid.  The Gruppe-S Engineering kit has a plug and play wire jumper harness so you don't have to hack up your stock wiring.

We turned to Gruppe-S Engineering for their 3 port boost control solenoid kit for the EVO. 3 port boot control solenoids work better than the stock two port because the 3 port is set up to intercept the boost pressure going to the wastegate actuator by being cycled by the ECU, the 3 port actually controls the amount of pressure the wastegate actuator sees.  This is more sensitive, faster acting and accurate enabling accurate boost control up to the limitations of the wastegate..

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Friday, April 22, 2011 3:23 AM
You just have to keep reminding me why I was so stupid to sell my Evo IX. Believe me, I know it already! Grrr...
Friday, April 22, 2011 4:18 AM
This keeps pushing me to get through college so I can afford that nice EVO and have my cake and eat it too: A reliable, practical, and fun project.
Friday, April 22, 2011 9:34 AM
Hmm... once you guys finish with this evo project (or maybe sooner), you should run an article to help us buy used Evo's... like common problems, tips on how to tell if the owner modded it, model/feature breakdowns, etc. :) No sense in teasing us if you're not going to properly equip us to go out and get one!!
Saturday, April 23, 2011 8:46 AM
That's a good pick up in power using the water injection. I'm looking forward to seeing how the Cosworth M3 cams do once installed in your motor.
Naji Dahi
Naji Dahilink
Saturday, April 23, 2011 10:03 AM
@ speedball,

It is very very hard to find a used evo that has not been modified. We get them to modify them. Keeping them stock is not the intention. What you need to do is find a used Evo that was properly modified. That is the problem. Most people that modify their Evos do not know what they are doing. I am seeing a lot of Evos come my way that are so poorly modified to make them untunable. I just send the customer away since I am only a tuner.
Eric Hsu
Eric Hsulink
Saturday, April 23, 2011 10:41 AM
Mike are you running a cat? What are you running for a cat back exhaust? If running an M3 cam on the stock turbo, exhaust backpressure will play a role in the outcome.
Mike Kojima
Mike Kojimalink
Saturday, April 23, 2011 4:07 PM
85mm big exhaust, clear all the way though not much backpressure.
Thursday, April 28, 2011 10:09 AM
So no methanol and it's only good for10 hp? Isn't that where most of the cooling comes from and the largest potential gains in power from tuning or do I have that mixed up?
Eric Hsu
Eric Hsulink
Thursday, April 28, 2011 12:00 PM
Your M3 is ready to pick up Mike. Let me know when you want to cruise by.
Mike Kojima
Mike Kojimalink
Thursday, April 28, 2011 2:49 PM
Looks like 32 hp to me, look at the dyno chart.
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