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?

Re: AUX input - IAT or WideBand o2?
 

Grouped? I do not understand. Do you mean grouped electrically via the circuit board you showed me?


Looks like not. From the Innovate LC-2 user guide. And I am not sure I can reprogram it to be the inverse.

"Analog Output is configured as 0 volt = 7.35 AFR and 5 volts = 22.39 AFR"



Anyway, this is not sounding useful for my setup. I will probably just stick with the IDC as the trigger with IDC and MPS as the reference signals.

Re: AUX input - IAT or WideBand o2?
 

Grouped means the signal inversion.

- IAT sensor voltage goes lower as the temperature gets higher. (Inverted)
- EGT, WBO2, boost goes higher as the danger zone is approaching. (Non inverted)

This means the user manual is correct. No need to re-configure. You can not use the WBO2 signal to compensate and boost drop failsafe.

Remind me what car do you have.

Re: AUX input - IAT or WideBand o2?
 

I have the same WBO2 as the OP.

Are you saying that the WBO2 cannot be connected to trigger a failsafe and drop boost? (if 0V is rich and 5v is lean?)

or are you talking flow compensation?

Re: AUX input - IAT or WideBand o2?
 

You can do both at the same time.

Even the WBO2 signal is inverted, ie 0v=lean and 5v= rich, it can still be done by solder link on the HFS4-v3.1.

Re: AUX input - IAT or WideBand o2?
 

I just ordered my system and will be making this connection as well.

Re: AUX input - IAT or WideBand o2?
 

Thanks for the order.

Are you good at soldering?

Re: AUX input - IAT or WideBand o2?
 

yes.

proof (laser replacement on my Denon DVD player):
https://www.youtube.com/watch?v=wjPkjHvHMPo


:)

Re: AUX input - IAT or WideBand o2?
 

Impressed!

Re: AUX input - IAT or WideBand o2?
 

Thanks but be more impressed that I resurrected a good old CD player for ~$16USD. Desoldering the anti-static shunt was a breeze. :)

So what bit of soldering are you alluding to here?

Are you referring to the wire connection between the WBO2 unit (brown wire of the Innovate LC-2) to the HFS-4's blue wire in the green harness? I think this is just a direct connection here unless you are suggesting something more..??

Re: AUX input - IAT or WideBand o2?
 

Linking two pads with solder, this might seem simple to you. Believe me, I have seen some real disasters of epic proportions.

Re: AUX input - IAT or WideBand o2?
 

Is it a supported configuration to just solder the COMP jumper pads while leaving the F and the W pads unsoldered? Only curious here.

How is flow compensated when the voltage goes up without spiking, indicating a lean condition - does it compensate by adding more spray?

I still wonder if using IAT as the AUX and compensating on that would be more useful to a jeep that will be crawling along a lot and susceptible to heat soak. It makes sense that a spike in WBO2 is the better choice for failsafe but I am referring to just compensation here.

Re: AUX input - IAT or WideBand o2?
 

If you don't require failsafe indication, leave F & W alone.

You also needs to decide either E (default) or A. I guess no soldering is require if the failsafe is for EGT or AFR.

The failsafe only swings into action after the system is triggered to spray.

Re: AUX input - IAT or WideBand o2?
 

Actually, upon closer inspection, it looks like it is IAT that is enabled by default and not EGT. The trace on the PCB goes to A, not E.

http://i1362.photobucket.com/albums/...ps8kpz029u.jpg

under the USB microscope....
 

Here is my work under the microscope. I changed things around. What I want to do is trim/comp. based on IAT and not use IAT as a failsafe.

http://i1362.photobucket.com/albums/...psvxdqwvi4.jpg


http://i1362.photobucket.com/albums/...psjycumjlv.jpg


It looks like IAT is the default.

http://i1362.photobucket.com/albums/...psmfxd84bs.jpg



And I reflowed the MPS setting.

http://i1362.photobucket.com/albums/...ps9j0lwcrr.jpg

Re: AUX input - IAT or WideBand o2?
 

Hi Richard,

Can you confirm that page 21, step 12 of the HFS4 v3.11 user guide is incorrect in that IAT is the default?

Is it the user guide or is the circuit board mislabeled?

I plan to switch from IAT to WBO2 for AUX compensation as well as fail safe.

Thanks!

http://i1362.photobucket.com/albums/...psmfxd84bs.jpg

Re: AUX input - IAT or WideBand o2?
 

You are correct I just checked, the user manual has not been update, this refers to page 21.12. V3 and v3.1 has IAT as default.
Pretty good soldering skills!

Re: AUX input - IAT or WideBand o2?
 

Thanks, Richard.

Can you publish here or elsewhere what voltage relationship is between the signal coming in on the Aux input and +/-10% flow adjustment?

In other words, what Aux voltage is required to

trim flow by 10.0%
..
trim flow by 1.0%

not adjust flow one way or the other

add flow by 1.0%
..
add flow by 10.0%


I would like to monitor the voltages of both IAT and WBO2 to try and figure which one will be more useful to me for flow compensation and then just tap into that circuit.

Re: AUX input - IAT or WideBand o2?
 

The voltage span that initiates a 10% change is 0-5V. If you starts to request full control for voltage less than 5V, you need two more trimmers: offset and gain. Not enough room on the circuit board to do this.

Re: AUX input - IAT or WideBand o2?
 

Is that +/- 10% or 10% range total?

When the output is 0v, is it trimming 10% flow and when at 5v, adding 10%?

Re: AUX input - IAT or WideBand o2?
 

+/- 5% is the swing.

At 2.5V is neutral. 0v=-5% 5V =+5%

Re: AUX input - IAT or WideBand o2?
 

Cool. Thanks. Understanding this helps.