[Diy_efi] Proportioning valves

[dan at w3eax.umd.edu]

My guess is the primary purpose of the regulator is safety.  If the rear 
wheels were to lock up before the fronts in an MR2, most drivers would 
cause disasterous consequences.  As a result, they may have intentionally 
been overly conservative in the settings to ensure that this never 
happens.

I have a VW and I'm aware of the VW load-sensing pressure regulator.  It 
was certainly a darn clever idea.  Unfortunately I don't have a solid axle 
like the VW.  I suppose its possible I could rig it up some how onto the 
strut assembly.

I just thought it would be an interesting project to try a quasi-ABS 
system.  I'm not real clear on how ABS works though.  It was my 
understanding the pump creates a huge amount of excess pressure and then 
the valve block is some how used to control the pressure at the wheels.  I 
wasn't clear whether or not its a PWM in order to maintain a specific 
pressure or if its just a too-much pressure, no pressure, too-much 
pressure, no pressure, too-much, etc.

I don't really see why a pump is needed if you just use the pressure 
applied by the foot and modulate the pressure so that the moment it locks 
up, you alleviate pressure (say 70% of pre-lock pressure or whatever it 
takes to let the wheel spin), then build back up to 95% of pre-lock 
pressure, then slowly walk upward until it locks again and repeat.  (I've 
also wondered if there is someway to sense lockup before it happens.

I realize this isn't EFI, but it is automotive electronic design so I 
figured people here might be interested.

dan