Need an explanation please.. tried the search

[NO_RSPECT]

OPEN LOOP and CLOSED LOOP boost control

I am installing a hybrid EBC.

I need to know what open loop means and how it works and the same for closed loop.

I DO NOT WANT TO KNOW HOW TO INSTALL IT ON A SKYLINE.. I WANT TO KNOW HOW EACH WAY WORKS.

thanks

RiaZ

P.S where are all the experts

[Zahos]

In a nutshell

closed loop gets feedback, so that it can re-adjust using some pre-set algorithm, or use fuzzy login as a means of correction.

Open loop has no feedback, so it cannot re-adjust, nor learn.

[JCMarshall_Law]

Yeah thats right, I just want to add something:

Fig 1: Open loop - the boost will reach a preset level, this may not actually be the boost pressure that it achieves because the controller has no way of judging what pressure has been reached. Thats why open loop controllers are "set and check types"

Closed loop - The controller will have a pressure sensor to tell it what the pressure is, it will then increases (or decrease) the pressure by a set ammount and checks the pressure again. based on that info, the contoller then increases (or decreases) by a set amount (smaller than the first) and that repeats untill the desired pressure is reached. Increasing or decreasing the pressure by smaller ammounts each time.

Figure 2 and 3 show a poorly designed (cheap) closed loop controller, Figure 1 shows a controller that overshoots the desired pressure (boost spike) and osscilates untill it finally reaches the desired pressure. Figure 3 shows a controller that takes too long to reach the set pressure - obviously not good.

Figure 4 shows a well designed controller that quickly reaches the set pressure without overshooting.

The maths for control systems engineering gets fairly complex, but if your really keen look at a uni level control systems text book, this stuff is in the first chapter.

[NO_RSPECT]

thanks for that patrick

So basically if the instructions for this Hybrid controller state that a Karmann sensor (mitsubishi AFM - GSR) vehicle can only run open loop..this i take it is because the vehicle doesnt come from factory with a boost gauge and has no map sensor so i think it asks for me to use the TPS reading instead and run open loop or some shizzle.

but if i install a map sensor then i should be able to run this controller in closed loop which would be the best way.

i hope thats right.

and now... off to the mitsubishi forums to check if anyone has done this... trust me mitsu forums... hmm...not much knowledge there as most cars are N.A

thanks again... if anyone else wants to add anything to this please let me know

[JCMarshall_Law]

Yeah, that sounds about right, the controller will need a MAP sensor for feedback if it is to operate as a closed loop.

[ix9]

Riaz,

I'm sure you could nab an R33 MAP Sensor and adopt it to the mitsi somehow, this would give you exactly what your looking for

P.S. I have the same Hybrid EBC, and in open-loop its quite dissappointing, closed-loop however is dam good!!

[NO_RSPECT]

yeah i got one of Mr Dobbie

good on him..

now to donk him on the head and drive away with that sweet r32.

back to it..

so yeah got a sensor and i think i will just hook it up as per how i feel like hooking it up and see if it works properly etc.. if it doesnt then i guess i am stuck with open loop which means.. guess what.. i have an EBC for sale..

but yeah otherwise CLOSED LOOP it is..

NICE