AUX input - IAT or WideBand o2?

[FI_Rubicon]

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.

[Richard L]

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.

[FI_Rubicon]

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.

[FI_Rubicon]

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.







It looks like IAT is the default.





And I reflowed the MPS setting.

[FI_Rubicon]

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!

[Richard L]

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!

[FI_Rubicon]

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.

[Richard L]

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.

[FI_Rubicon]

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

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

[Richard L]

+/- 5% is the swing.

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