Anybody want to proof my wiring diagram?

I just received my DDS3-V8 (man is thing sweet!) and I’m in the process of working up a solution to interface the failsafe with my existing SMC Alky Injection third-party system.

So far I’ve chosen PWM as the failsafe trigger mechanism interfaced with negative terminal of my SMC pump and activated via the “high/low” flow condition window. Then I combined the trigger with the “MAP-SW” failsafe output ultimately disabling my boost solenoid valve in the event a failure is detected, which in-turn will drop boost to wastegate pressure.

Normally this would be a fairly strait forward wiring effort; however I run my Alky system a little differently which is making the wiring more complicated. I prefer to run my SMC system with a master enable/disable switch. This allows me to cruise around on the street with the alky system disabled and running my pump-fuel only EM MAPs. Then for performance events or some aggressive street driving, I enable the system and move over to my Alky specific MAPs. Unfortunately when using the boost-cut (solenoid ground interrupt) failsafe approach of the DDS3, it leaves the circuit open when not powered up. Obviously this would result in no boost above wastegate pressure whenever the DDS3 is not switched on. So my wiring solution had to take this into account and provide a work-around.



http://66.49.172.173/subaru/misc/SMC_DDS3_wiring_v1.jpg



In this diagram, the ground circuit of the boost solenoid valve is interfaced with a relay and the failsafe system.

When the “Master Enable Switch” is disabled (OFF), the coil of “Relay-2” is not energized leaving terminals 30 & 87a with continuity closing the boost solenoid circuit. This will enable complete boost solenoid functionality when the alky system is completely turned-off.

When the “Master Enable Switch” is moved to enable (ON), “Relay-1” supplies power to both the SMC and DDS3 systems. Additionally power is supplied to “Relay-2” which energizes the coil and breaks continuity leaving terminals 30 & 87a open. This puts control of the ground interrupt into the hands of the DDS3 system; which when powered up closes the leads under normal operation, then opens the circuit upon failed state.


So if anybody sees anything fundamentally wrong with this diagram or third-party failsafe system integration using the DDS3 product, I’d appreciate your feedback...

The system will work exactly as you described.

Very well configured.

Great, thanks Richard!!! :D

I got to tell ya, so far I’m incredibly pleased with the DDS3 failsafe kit. Just opening the box and inspecting the components and you can tell it’s definitely of superior craftsmanship and quality. Can’t wait to get the system installed and in use… ;)

Love to see some pictures of the install, please.

You know when meth is switch off, you can still dial in high boost? just to be sure

Well if I understand your question correctly; yeah I run two boost profiles on my EBC. One at 19psi for strait pump gas (injection system off), and another at 23psi for injection system on. Each is dialed in with their own wastegate settings based on the underlying EM map in use. ;)

I was referring to the EBC.

When the WI and DDS3 is switch off (master enable switch -off), you are still free to dial in both boost profiles. Is this intended?

Yes both are still available, although without the alky system enabled, I only use the “pump gas – 19psi” profile. The EBC is completely standalone and therefore has no way to know if the alky system is enabled or disabled. Switching boost-profiles on the EBC is a manual process.

To engage my alky system takes 3 steps:
Turn on the Alky system master enable switch.
Turn my EM MAP selector switch to the appropriate alky MAP.
Select the applicable boost-profile within my EBC.

I can do all this moving down the road however requires that I depress the clutch and drop RPM to below 1k for the EM to switch MAPs.

Would be nice to modify all three systems under one procedure, but since none of them interface with eachother, doesn’t seem like a possibility. :(

OK, you have a procedure to safe guard any mistake so high boost conditions will not exist as long as you follow the procedure.

What is your wastegate pressure?

12.5psi spring...

I’ll be setting my SMC controller “start-spray” window right at wastegate pressure, then tune my latest Alky maps from 12psi on up. That way if the DDS3 opens the boost solenoid due to some fault, it will just drop to wastegate pressure and still have sufficient fueling at that lower boost level to not go dangerously lean.

I think the only way you can avoid accidentally set the EBC to 23psi is to allow the DDS3 to remain on at all time. Set the failsafe to cut in at 20psi.

Based on your #5 post, DDS3's failsafe need not be enabled at 19psi.

Bumping an old thread.


OP, how has this worked for you?