AUX input - IAT or wideband o2?
 

Hi there,

Given a choice between IAT or wideband o2, which one would be a better choice as an AUX input with the HFS-4 v3.1? I have both available.

FWIW, this is a supercharged gas motor (3.6l pentastar). The TVS supercharger is water/air intercooled and bolted to a stock motor. It peaks at ~9.5psi @ redline.

I plan to run pure water ~80% of the time and occasionally swap out the jet(s) to run 50/50.

thanks!

edit: this is a non-DI motor.

Re: AUX input - IAT or WideBand o2?
 

Looking at this from a simplistic point of view, I would think that WBO2
would be better than IAT. Under boost the HFS-4 will already have active
failsafes to guard against loss of water flow, which I imagine is the most
likely cause of the IAT spiking.

However, if there was a loss of fuel pressure for any reason, the AFR could
spike into dangerous territory very quickly. Unless the engine management
or engine instrumentation was equiped with a warning alarm to force an
emergency shutdown under a sudden lean condition, engine damage could
easily occur before the driver realised the danger.

Than would be my reasoning. But I have no experience with water injection
or the HFS-4, so I stand open to correction :)

Cheers... jondee86

Re: AUX input - IAT or wideband o2?
 

The blue wire of the green harness has two functions with one single signal:

1. hi/lo crossover failsafe
2. trims flow

I believe you are referring to the failsafe. In this case, WBO" signal will be a better bet. At the same time, you can active the flow trim/supplement based on the AFR. (this option requires some soldering work).

Re: AUX input - IAT or WideBand o2?
 

Yes, the blue wire in the green harness.

Yes, the idea if I understand the function is to use the aux input input to trim flow.

I am using an Innovative LC-2 for wideband o2. This device has two configurable outputs. The first output (a yellow wire) provides wideband o2 signal to my Diablosport Trinity for data logging via a 2.5mm jack. The second output is unused and configured for lambda by default but can be reprogrammed with a PC to be a 0-5v wideband output instead like the first output. I was thinking to just link this second output of the LC-2 (brown wire for the lC-2 if I recall) directly to the HFS-4 blue wire. This would of course be a soldered connection with heat shrink tubing and all that good stuff. :)

I can tie into the OEM IAT wires as an option if I want to use that signal instead.

edit: The first iteration of my install with be water only and no tune so no failsafe. I may advance the ignition timing on my own using the Diablsport Trinity, though. I will eventually work in a failsafe using a 3 way solenoid to cut boost and then get a custom tune for 50/50.

Re: AUX input - IAT or wideband o2?
 

Thanks, Richard. By soldering, are you referring to the circuit board that we discussed in email or page 22 of the instructions, step 12 where it suggests to solder a jumper for the IAT change?

If the circuit board is what you are referring to, wouldn't the signal coming from the Innovate LC-2 already be conditioned?

Re: AUX input - IAT or WideBand o2?
 

I am confused, which version of HFS4 do you have. Or let me know the serial number.
Page 22 is referring to the flow sensor table. I cannot see a step 12.

Re: AUX input - IAT or WideBand o2?
 

Sorry. Page *21*, bullet 12. Looks like WBO2 is already selected by default so no cutting or soldering there.

I will be ordering the HFS-4 v3.1 from you guys in a few days.

What I hope to do is to connect the blue wire of the green harness directly to the WBO2 output of my Innovate LC-2. I am hoping that the 0-5v signal will be usable as is without conditioning.

Re: AUX input - IAT or WideBand o2?
 

I just realised that myself.

You need to group the signals as below:
(failsafe and compensation)

IAT and WB02 ......... inverted.
EGT, over-boost etc ......... (default) no inverted

The user manual may need correction.

Re: AUX input - IAT or WideBand o2?
 

HFS-4 v3.1 manual states:

12. AUX input select: EGT or IAT
EGT, WBO2 (default) or cut thin track to“E”
and solder link “A” for Inlet Air Temp sensor.


Are suggesting that this is the correct text?

12. AUX input select: EGT or IAT
EGT (default) or cut thin track to“E”
and solder link “A” for Inlet Air Temp sensor or WBO2.

Re: AUX input - IAT or WideBand o2?
 

This is the error of the manual, needed correcting. WBO2 should be grouped with IAT.
Can I assume WBO2's 0v output is lean and 5V output is rich?