FAQ: Installing the AUTO I/C Spray the right way

[mrsaturn7085]

First things first - you need to have a standalone with 1 low-side input and 1 pulsed ground output available. Wiring this to work with a JDM (16-bit) ECU on a 32-bit chassis loom is well beyond the scope of this post.

I'm going to keep this short and sweet, and hope that it will just become a sticky. This is intended for the GD chassis and you will need to reference the FSM. The following image explains it all:



Red highlighted lines are short-length added wires.
Yellow highlighted lines are dash-spanning added wires.
Dots attached to red or yellow highlighted wires are splices.

You only need to interrupt a single wire in the entire factory harness to make this work. You will need to make a few splices elsewhere, but everything will continue to work as OEM if you follow my wiring plan. This is useful to note if you ever choose to replace the standalone ECU with a factory one.

This wiring replicates the OEM wiring in that it will automatically disable the I/C AUTO spray when the water tank is empty. If the AUTO switch is depressed with an empty tank, the orange 'active' light will turn off and the I/C water low warning light on the dash will illuminate.

Part Notes:

A - 1.5A diode (~20VDC or better rating); the OEM part can be sourced from a junkyard rear wiring harness near the OEM I/C spray tank in the trunk. You don't *need* the OEM part, but it has a handy in-line holder. (Located near ECU)

B - Nissan relay; the easiest way to source this is to buy a used DRL relay pack from just about ANY Subaru with DRLs. The following image is one of about 100+ available cheap on eBay. You want the black relay and be sure to buy it with the chopped connector pigtail! (Located on I/C spray timer bracket)



C - Subaru relay (82501AE03A aka 82501FC100) w/Hella HL87125 micro relay holder; can't get much easier than this. (Located near I/C spray timer bracket - just zip-tie it in there somewhere)

D - Auto I/C switch (83001FE030) and connector; the connector is the tough part if you don't find the switch with a pigtail. The generic (non-keyed) connector is a Yazaki 7123-1360 or Sumitomo 6244-5061. Searching for a "Sumitomo 6 Position 090 MT Connector" will likely get you what you need. (Located next to the OEM I/C Spray switch)

I recommend the following splices (they are expensive, but MIL/Aero quality); you will need blue (medium) and yellow (large) sizes, but it doesn't hurt to have some red (small), as well:

650-D-436-38 (D-436-38)
650-D-436-37 (D-436-37)
650-D-436-36 (D-436-36)

You need the proper crimp tool and a heat gun capable of 700 deg F to install these.

Now as far as the ECU signals go, the wire with the inline diode is the input for the AUTO mode. When the AUTO switch is depressed, this wire sends a switched ground signal to the ECU. The ECU must be set to read this pin as an active-low input (and therefore must have an internal pull-up resistor, usually to 5 or 12 VDC).

The other ECU pin is the output pin. When programmed conditions are met, this wire sends a 0.5 sec ground signal which is extended to 2 seconds through the OEM timer. The delay between 0.5 sec pulses should be programmed to be short enough to keep the IAT cool without running out of water too soon. With a 12 liter tank, I have my current 'OFF' time delay set to 5 seconds, but might adjust it as needed.

The JDM ECU has an elaborate algorithm that only allows the AUTO spray to happen when a handful of conditions are met (minimum RPM, minimum boost, minimum IAT, minimum TPS, etc.). MOST aftermarket ECUs will NOT allow this many variables, so I suggest one of two options:

ON above 90% throttle, OFF below 80% throttle

-or-

ON above 40 deg C IAT, OFF below 38 deg C IAT

The hysteresis will prevent hitting points where your AUTO I/C spray will be clicking on and off frequently.

Lastly, for the GR and later folks, here is the OEM wiring for the Spec C; it only differs in a few small ways from the GD wiring, so you should be able to reverse-engineer your own solution without much trouble:

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[mrsaturn7085]

And the results?

YouTube

YouTube

YouTube

YouTube

[Profoxcg]

This is pretty cool (pun intended!!)

For a track car running a top mount, would the IC spray help?
Why did they do away with it in the newer STI's ? do you happen to know or speculate?

[mrsaturn7085]

Yes, the I/C spray helps maintain stable IATs under load due to evaporative cooling. Soaking the I/C is less beneficial than having a constantly evaporating thin coating of water.

The answer to your second question is cost. Rather than make this a normal STi part with an upgraded Spec C version, the newer models just make it a standard part on the Spec C and an option part you can buy for the STi.

From 2008+, the GpN option part used a simple rotary timer to spray and an on-off switch. Only the Spec C retained the AUTO function from 2010-2014.

[Cmurray902]

Originally Posted by mrsaturn7085

Yes, the I/C spray helps maintain stable IATs under load due to evaporative cooling. Soaking the I/C is less beneficial than having a constantly evaporating thin coating of water.

The answer to your second question is cost. Rather than make this a normal STi part with an upgraded Spec C version, the newer models just make it a standard part on the Spec C and an option part you can buy for the STi.

From 2008+, the GpN option part used a simple rotary timer to spray and an on-off switch. Only the Spec C retained the AUTO function from 2010-2014.

Spraying the intercooler will obviously lower temps coming out of tmic thru evaporative cooling but since the IAT is located before the turbo and not in the throttle body how can it stabilize IAT temps...? If running a FMIC with an IAT tapped before the throttle body that would make sense but on a stock TMIC it doesn't add up to me. Am I missing something? Or maybe you're referring to the actual air temperature and not the sensor readings.

[mrsaturn7085]

Originally Posted by Cmurray902

Spraying the intercooler will obviously lower temps coming out of tmic thru evaporative cooling but since the IAT is located before the turbo and not in the throttle body how can it stabilize IAT temps...? If running a FMIC with an IAT tapped before the throttle body that would make sense but on a stock TMIC it doesn't add up to me. Am I missing something? Or maybe you're referring to the actual air temperature and not the sensor readings.

All AUTO I/C spray models (i.e. the Spec C) included a post-throttle secondary IAT sensor, for this reason. The STI GpN ECU converted the motor to speed density and having all the sensors in-place from the factory was a requirement of GpN regulations.

The fact that actual IAT will still be stabilized is true of standard MAF IAT readings, but you need to be careful about programming the thresholds right - if you program it to spray above 40 deg C but you're using MAF IAT which never sees this high of a value, it would be pointless; in this case, I would go with a full-throttle spray algorithm.

[Profoxcg]

I was thinking of installing an aftermarket kit with a "manual" switch to be driven by certain parameters not, really the car's ecu.

Can someone what is triggering the spray on the spec-C?

My car is running MAF, would need to Speed density to run one of these setups? - sound like it doesn't it?

[mrsaturn7085]

Originally Posted by Profoxcg

I was thinking of installing an aftermarket kit with a "manual" switch to be driven by certain parameters not, really the car's ecu.

Can someone what is triggering the spray on the spec-C?

My car is running MAF, would need to Speed density to run one of these setups? - sound like it doesn't it?

The Spec C has a set of 2 dedicated ECU pins to control the switch input and trigger output.

You don't need speed density to benefit from this - just use a full-throttle trigger with hysteresis as noted in my guide.

The GD Spec C parameters are as follows (all must be met to spray):

MAP (values below listed as gauge pressure, not absolute)
RASC (ON over 2.02 PSI, OFF under 0 PSI)
GpN (ON over 5.80 PSI, OFF under 3.87 PSI) - this was likely raised to prevent the I/C spray from triggering under anti-lag boost spikes
*5.80 PSI = 40 kPa; 3.87 PSIg = ***8532; of 40 kPa

Engine Speed
RASC (ON above 4000 RPM, OFF below 3800 RPM)
GpN (ON above 3200 RPM, OFF below 3000 RPM) - GpN cars shift around 5300 RPM due to the restrictor; the threshold had to be lowered for this reason

ECT
(ON above 80 deg C, OFF below 75 deg C)

IAT
RASC (ON above 20 deg C, OFF below 18 deg C) - this is based on the MAF IAT (pre-turbo, i.e. ambient temp.)!
GpN (ON above 40 deg C, OFF below 38 deg C) - this is based on the secondary IAT behind the throttle!

I/C AUTO Switch Depressed

Keep in mind that on the GpN ECU, the AUTO switch also enabled anti-lag, so the reasons for the above values are related.

You'll notice that the GpN AUTO spray is a seriously functional spray, while the standard Spec C function is just designed to spray when you gun it on hot days (above 20 deg C under-hood ambient).

The GR Spec C parameters were simplified a little but similar.

EDIT: My mistake, the GR is nearly identical - AUTO I/C Spray thresholds from the 2008-2014 GR factory service manual:

[Profoxcg]

what is RASC and GpN stand for?

ECT = what? engine coolant temp?

[Profoxcg]

full-throttle trigger with hysteresis

meaning turn on between 98-100% and off below those values? <98% just and example.
I am sorry I am at work so I cant watch your video. Sorry if it explained there

[mrsaturn7085]

RASC = RA Spec C; RASC is the technical name for the trim level in Japanese part systems
GpN = Group N; Group N is a class of rally competition in FIA

Hysteresis on the throttle being something like ON above 90%, OFF below 80%. This prevents rapid on/off behavior if you hover around 90% throttle.

[Profoxcg]

Thanks

[contaminatrix]

this is waaaaaaaaaaaaay too elaborate for my 4 iq points in electrical engineering haha

i'm planning to go for a rudimentary method with my switch under my pedal; which will activate a relay, which will run a motor.

let me get it all in place

(yes i realise i'm year late).

[jemmery]

thats dank

[edlamx]

Thank you so much

[rwense]

Originally Posted by contaminatrix

this is waaaaaaaaaaaaay too elaborate for my 4 iq points in electrical engineering haha

i'm planning to go for a rudimentary method with my switch under my pedal; which will activate a relay, which will run a motor.

let me get it all in place

(yes i realise i'm year late).

Any update on this? I cobbled together my own TMIC sprayer from no name windshield washer reservoir parts for like $30 with a momentary switch. I've considered getting a toggle to switch on when I start an autox run for example but having a switch under the pedal would be slick. I guess the only problem would be to make sure it's full so I dont burn the pump out.