Feature request: IACV/IACVCMD sensors

Floppie · Post by **Floppie** » Mon Sep 13, 2010 8:26 am

Here I am again with a fun feature request :) I'm running the 1.4.1 beta and I have to say, the Indicator display element is wonderful, thanks for listening on that one.

Anyway, here's another idea I had - I'd imagine that the ECU keeps track of how wide the IACV should be open (presumably a 0-100 percentage type deal), and since it's a closed loop system like the intake cam advance and lambda control, I'd imagine it also keeps track of how wide the IACV is actually open.

Now, my question is, is it possible for the Kpro daughterboard to sniff this information from the ECU and report it back to KManager like the other sensors? It would be very helpful for diagnosing idle issues - you could look at the datalog and see if the IACVCMD and IACV lines deviate from each other significantly when it's trying to change; if so, need to clean/replace it.

kb58 · Post by **kb58** » Mon Sep 13, 2010 10:22 am

While it's closed-loop, it's not "really" closed-loop. Yes, if the valve is opened, the engine speeds up, and if it's closed the engine slows down, but it would be tough to have a hard relationship due to engine speed being dependant upon other things, like a vacuum leak. If it got a leak, it's the same as the valve being more open than it is, so the "feedback" would show a wrong value. I don't think it can be done and give useful - and accurate - feedback.

Floppie · Post by **Floppie** » Mon Sep 13, 2010 11:36 am

Actually, my thought was that the ECU is aware of how open the IACV "really" is versus how much it's trying to open it - similarly to how there's an actual wideband O2 sensor and a target lamba; an actual CMP sensor and a target intake cam advance; etc.

EDIT: Keeping in mind that I might be wrong - I haven't looked at the IACV wiring; but I would assume that the would be the easiest way for Honda to have engineered the system would be to make the ECU aware of actual IACV opening width.

kb58 · Post by **kb58** » Mon Sep 13, 2010 1:04 pm

That's what I'm saying, that there is no feedback. It's PWM (pulse width modulation) setup, and I think the ECU just assumes it went to where it was commanded - AFAIK there is no potentiometer feedback.

Floppie · Post by **Floppie** » Mon Sep 13, 2010 1:36 pm

Well, that puts a bit of a damper on that...regardless, having the target width would still be very useful.