Im really interested too in whats actually going on through a corner. I only did a 150psi sensor because I think if its over that its probably max or in more rare situation. But I'll be finding out!

Right now it will be sharing a gauge with my oil pressure sensor so as soon as I determine some of my oiling changes are solid, then I'll change the plugs. This is just temp till I run wires for full time logging of it though.

 

No, it's a replacement part. Idk why they would suggest a hose do this possible issue. There should be clear evidence the rack/FSB rubbing of it actually is.

But you also shouldn't be taking advice from them on really anything.

 

Max pump pressure is about 15 bar or 217 psi, you really might see it max out. How fast is your logger? As the ACD valve will ramp up the pressure many times within the same corner.. Tends to react to steering angle and steering speed quite fast..

 

Steering angle sensor has to be logged with this in order to have any meaningful data! Along with the throttle positioning and Gs

 

Max sampling is 1000hz, certainly more than enough. Im not sure the response time of the actual sensor but I suspect its at least adequate compared to the physical response of the system.

Yes-ish. I can interpolate for now with other day what Im doing in the car but I will be tapping into steering angle encoder. I just need the time to learn how to program CAN outputs from an arduino for the RaceCapture to log.

First step though, see what the pressures are doing and have fast they swing around.

 

Couldn't you just log the ACD ecu directly? I vaguely remember doing this years ago with Evo scan and getting things like wheel speed sensor, steering angle sensor, etc. Probably pump pressure is in there.

I also am relocating my ACD pump but shied away from AN lines because max pressure IIRC exceeded typical AN fittings. Safer to run brake line fittings.
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Wasn't 15 bar the normal max operating pressure but the theoretical max 20 bar? I seem to recall some debate there on what the ACD unit could actually be pushed to do in the tuning thread.

 

I dont necessarily care about the other parameters (other than wheel speed, but I have a solution for logging wheel speed. Hint, its not straight forward but doable). What I care about is what the pressure is in context of whats happening on course, what the yaw rates and lateral/longitudinal loads look like. I basically need to wrap my head around what the center diff is doing when the car is acting any given way through the various parts of a corner or straghts.

As for AN lines, I dont recall the max line pressure but its something over 1000psi. The compression ring fittings do have a limit that may be pushed with the ACD pumps potential. I bought a proper AN flare too and flared the OEM 5/16" EVAP line and used that to run the fluid forward. As luck would have it, the line is about the same length as the OEM line (OEM wrapping all the way around the engine bay and all) and its the same diameter. So it works out perfect. And then the

EDIT: Also to add, Ive had this line in the car maybe 3 years already with not a leak. So it has been totally solid.

 

exactly. We did some testing by logging the OE ACD ecu and iit is pretty evident that the steering input is a major factor. However, the OE ACD ecu sample rate is pretty low..

One of the things we noticed was that at steady state cornering the acd was open..

 

There is a small mechanical pressure limiting valve in the pump and it opens at about 15 bar

 

yeah, evoscan will log the acd ecu...

 

You should take a look at the ACD thread. It's taking a lot of inputs but all it's doing at the end of the day is modulating line pressure. That said, there's nothing straightforward about how it's modulating the line pressure and the maps (what we know of them in open source community) is complex. I don't really think the line pressure logging will make sense unless you look at the ACD tuning and log it's inputs to see what it sees and is reacting to.

​​​​​​Sounds like you run better AN fittings than I am (also I don't have a crimper). My fittings are compression type and are rated to 55psi max. I'm also using the evap line to run acd fluid from the back. Just flared and using OEM style brake line fittings.

 

Right. I think last time I was "in" those threads some people were trying to look at how to override the valve and boost ACD line pressures.

 

you could setup an arduino to log all those signals. Or if you wanna be fancy a mixed-signal oscilloscope.

 

I guess you could pull out that valve from the pump body and put in a heavier spring but it is questionable if the pressure accumulator would like that.
Having said that, first thing that "we" should do is log individual wheel speeds / axle speeds and see if more locking is needed at all..