WTF does closed loop / open loop refer too ?
- Thread starter vr4
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vertex_vr4
Well-Known Member
Closed loop = the ecu uses information from the car's sensors (inputs) to try and improve its outputs. This usually means getting a better air/fuel ratio.
Open loop = the ecu doesn't give a flying ducky about the sensors that could improve the output - it just goes on a preprogrammed set of A/F targets that the ECU manufacturers thought should be "safe" (read pig rich)
From memory, the ECU uses a TPS -> Load map to determine whether is should be in open loop or closed. The idea being that for such and such TPS position you should be between 2 certain load values. If you are - great! your closed loop. If not then your in open loop.
The more common way of figuring it out is a cloud of smoke in your rear view mirror - particularly visible at night in the headlights of the car behind you. :twisted:
Open loop = the ecu doesn't give a flying ducky about the sensors that could improve the output - it just goes on a preprogrammed set of A/F targets that the ECU manufacturers thought should be "safe" (read pig rich)
From memory, the ECU uses a TPS -> Load map to determine whether is should be in open loop or closed. The idea being that for such and such TPS position you should be between 2 certain load values. If you are - great! your closed loop. If not then your in open loop.
The more common way of figuring it out is a cloud of smoke in your rear view mirror - particularly visible at night in the headlights of the car behind you. :twisted:
Yeah that's right...
Closed loop uses the Oxygen Sensor and Air Flow Meter to adjust the air-fuel ratios.
Open loop just runs on pre-set air-fuel ratios.
Most aftermarket ECU's that run on open loop have temperature compensation and the like built in to adjust mixtures and timing.
Closed loop uses the Oxygen Sensor and Air Flow Meter to adjust the air-fuel ratios.
Open loop just runs on pre-set air-fuel ratios.
Most aftermarket ECU's that run on open loop have temperature compensation and the like built in to adjust mixtures and timing.
Cheers 4 the info guys, could someone clear up a couple more questions ive got,
1) What does TPS mean im guessing- throttle postion sensor.
If thats right the ecu go's open loop when the gas pedal is pressed past a certain point and the cars at a certain load level, how often is it going to go open loop, i mean does it go open every time you foot the accelerator :?: ,
2) Could you be a little clearer in regard to being between 2 load levels, how does it determine what load level its at :?: , just pretend i don't know shit bout this.
3) So when in open loop an AFC has no effect?, cause it changes the A/F ratio by altering the Air flow metre signal.
Does a AFC only work in closed loop :?: .
Cause im running rich up top under acceleration, but with this reasoning a AFC won't do shit to change A/F levels under acceleration, it would only work at idle/cruise? This can't be correct? :?
1) What does TPS mean im guessing- throttle postion sensor.
If thats right the ecu go's open loop when the gas pedal is pressed past a certain point and the cars at a certain load level, how often is it going to go open loop, i mean does it go open every time you foot the accelerator :?: ,
2) Could you be a little clearer in regard to being between 2 load levels, how does it determine what load level its at :?: , just pretend i don't know shit bout this.
3) So when in open loop an AFC has no effect?, cause it changes the A/F ratio by altering the Air flow metre signal.
Does a AFC only work in closed loop :?: .
Cause im running rich up top under acceleration, but with this reasoning a AFC won't do shit to change A/F levels under acceleration, it would only work at idle/cruise? This can't be correct? :?
JAP63
E III Recaro Pilot
vr4 said:
Yep
vr4 said:
Ill have a go at this one,i think that if a car is in constant open loop,it never reads from the O2 sensor,therefore watever values your tuner has put in,you car will follow..thats why people say they are in "rich' mode...cos usually at cruise they tend to waste fuel because the tune isnt optimally adjusted by feedback....from the O2 sensor..even in your standard computer,its all open loop values from a map once your past a certain throttle/load..the O2 sensor only trims around cruise and idle...
vr4 said:
I think its determined upon maps that detrmine load upon throttle position and RPM..so as your throttle positon changes in respect to your RPM..then the load becomes different..
vr4 said:
Big debates here..it will work in open loop though..i was askin the exact question a while ago..vertex VR4 will know..he gave me plenty of answers on it...ill have a shot in laymens terms...dont forget..the Airflow meter is always reading..it always has a signal/voltage (except for MAF overun)
From what i could gather it will work in open loop because it simply amplifies the input signal..so if you have a +1,then the open loop value gets a +1 tacked on to it...so it should therefore put in more fuel..at idle and closed loop is where the grey are exists..
Because youre telling it to give a value,but the O2 sensor is trying to give it its own value,based on what it thinks it should be,because of exhaust gas readings etc....
vr4 said:
An afc would help...but a fuel reg is important too,if you have upgraded your pump and its pushing more fuel...the reg can help bleed alot of that unneeded fuel back to tank,instead of feeding it to the injectors...but..as you originally asked,an AFC should still reduce fuel at the point of the map...people lean their motors out and blow them up with SAFC's..so they can make you run lean.
