Idle conversion stepper to solenoid Subaru WRX

[DenisAlmos]

I'm using a V6 engine in a V4 WRX

My problem is I can't control idle because the car wiring is a 3 wires for a solenoid I suppose and the throttle body is supposed to have a 4 wires stepper motor.

Can you confirm if V3-V4 G4X is able to control a stepper motor?

If not do you think another solenoid can fit the Subaru throttle body?

I’ve been using rotational idle but engine don’t warm up over 50°C so it’s not ideal for a track day car.

[Adamw]

No you want be able to do a stepper motor with the V3/4 plug-in, it doesnt have Aux 5 or 7 available or the ECU hold power circuit to reset the idle valve after power off.  

I dont know the interchangeability of the various manifolds/throttles/idle valves for the early EJ's very well so cant off much advice on the hardware, but you will need a 2 or three-wire idle valve.

[dx4picco]

I would hazards guess you should put a new age TB at least (or with manifold as it has same head pattern as V5-v6).

New age TB needs only one aux and PWM.

[DenisAlmos]

Thank you @Adamw 

@dx4picco what engine code or model and year are you talking about?

[koracing]

On 2/10/2024 at 1:57 PM, Adamw said:

No you want be able to do a stepper motor with the V3/4 plug-in, it doesnt have Aux 5 or 7 available or the ECU hold power circuit to reset the idle valve after power off.  

I dont know the interchangeability of the various manifolds/throttles/idle valves for the early EJ's very well so cant off much advice on the hardware, but you will need a 2 or three-wire idle valve.

Is there any issue setting the stepper to reset at key on instead of using a hold power to reset at power off?

[dx4picco]

should be from any wrx or sti before DBW cars

[DenisAlmos]

As my car as a circuit breaker it makes more sense to set the stepper motor reset at ECU wakeup than hold power anyway

It’s not a problem for me to wait a second before startup

[KennyJ]

those steppers are a pain , even if they work

 

i bypassed many of them , just block them and cut a groove in the rubber

use idle ignition or rotational idle as a solution if its not a road car

you can setup a virtual aux with ect temp >78°c as activation for example

[DenisAlmos]

On 2/20/2024 at 7:05 PM, KennyJ said:

those steppers are a pain , even if they work

 

i bypassed many of them , just block them and cut a groove in the rubber

use idle ignition or rotational idle as a solution if its not a road car

you can setup a virtual aux with ect temp >78°c as activation for example

I understand your position, thanks for your advice.

As mentioned above, with rotational idle the engine doesn’t warmup, not good for a track day car that’s going to run a few laps, it needs to perform quickly.

Unfortunately, ignition idle was way out of range, the engine sits at too high with a throttle set for startups. Maybe I can find an intermediate position to make ignition idle to work.

As another solution, I saw a Group A Subaru with a manual cable command for anti-lag using the OEM speed regulator cable attachment on the throttle. Maybe I can use this solution for startup only, like a starter on carburetors but an automatic solution always is sexier.

[KennyJ]

many 90's nissan have a automatic closing valve working like an electric inverted thermostat , but for air

 

you feed it 12v and it closes over time

ca18 had it , rb20 rb25 ...

 

 

[Adamw]

I would either fit the later EJ throttle which has the single aux idle valve as Dx4picco suggested above or use a common bosch 2 or 3 wire valve that have simple hose barb type connections.