close loop


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ntahlerz

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guys...a few question regarding closed loop.
when does it come to play?
can close loop be tuned?
can it be disabled?

i want to understand it as much as possible..tq
 
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ntahlerz said:
guys...a few question regarding closed loop.
when does it come to play?
can close loop be tuned?
can it be disabled?

i want to understand it as much as possible..tq
Click to expand...

from the instrumentation terms...
closed loop have a feedback signal to controller to make adjustment.The controller carried out the adjustment base on the setpoint.

It can be disabled and will change from closed loop to open loop.

just my 2 cents...
 
To disable closed loop you would need either a chiped ecu or a after market ecu with software. Closed loop keeps your afr's as close to 14.7 as possible up to x amount of load (ime sure its over 80% but not 100%) then the ecu will just use the cell's in the map without making any correction. I would'nt mess with this unless you know what your doing and have the right equipment because you could seriously damage your engine.
 
thanks jt...
rich, im not messing with it or anything...juz want to understand it..
im having a problem with my engine..the idling like to go very low that my engine shakes the car..as low as 300rpm..sometimes it dies when the ac is turn on. so i'm trying to find out what is the problem..

does closed loop have its own mapping?
 
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ntahlerz said:
thanks jt...
rich, im not messing with it or anything...juz want to understand it..
im having a problem with my engine..the idling like to go very low that my engine shakes the car..as low as 300rpm..sometimes it dies when the ac is turn on. so i'm trying to find out what is the problem..

does closed loop have its own mapping?
Click to expand...

There is a high / low fuel table. In closed loop it can read from either once below a certain load value but there is also correction tables which come in to account. The ecu will want to reach 14.7 afr in closed loop.

I would take your IACV off and give it a clean that could be the cause for your idle issue.
 
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Vtec6000 said:
There is a high / low fuel table. In closed loop its reading from the low cam table but there is also correction tables which come in to account. The ecu will want to reach 14.7 afr in closed loop.

I would take your IACV off and give it a clean that could be the cause for your idle issue.
Click to expand...

Hmmm are you sure its not load & Ect based ?
 
ntahlerz said:
thanks jt...
rich, im not messing with it or anything...juz want to understand it..
im having a problem with my engine..the idling like to go very low that my engine shakes the car..as low as 300rpm..sometimes it dies when the ac is turn on. so i'm trying to find out what is the problem..

does closed loop have its own mapping?
Click to expand...

What ecu are you running ?
 
Rich777 said:
Hmmm are you sure its not load & Ect based ?
Click to expand...

Not sure what you mean mate? If your referring to when it switches to open loop then yes there is a set load that once you go above it switches and there is a min. ect(temp.) for closeloop long term trim. Did I say different?
 
Vtec6000 said:
Not sure what you mean mate? If your referring to when it switches to open loop then yes there is a set load that once you go above it switches and there is a min. ect(temp.) for closeloop long term trim. Did I say different?
Click to expand...

I thought you was trying to say that closed loop was just in the low cam table and not the high cam table.

Sorry if ive got this wrong.
 
Rich777 said:
I thought you was trying to say that closed loop was just in the low cam table and not the high cam table.

Sorry if ive got this wrong.
Click to expand...

I see what you mean after reading back over my first post it seems like that alright but not what I meant as god knows those who insist on using vtec controllers to put there vtec point down to 3500rpm will be running closed loop on the high cam table alot:))
 
im using chip ecu running on crome...i have clean the iacv.if i switch back to stock ecu, it would be fine..
 
no i dont.but my tuner does.im trying to pin point what is causing this.can a faulty o2 sensor cause this?or the afr being too rich on idling or on low rpm?
 
Try disconnecting the iacv plug with car running and see what it idles at. It may stall so have someone hold the throttle open a little and gradually release the throttle. If it doesn't idle around 550rpm and/or keeps stalling you need to adjust the base idle screw on the throttle body. I can give you a guide to doing this but will wait to see how this works out for you before I write it up as it might not be the trouble.
 
ive adjust the screw to fully open.still the problem is there.but i havent try to disconnect the iacv plug.i'll give it a try.and i'll tell you the result.thanks.btw, since im running on obd1 ecu, can i use a obd1 iacv from a b16a?can i use it with b18c R intake?
 
vtec6000, ive done it, but the problem still occur.switching back to original b18c r p73 ecu.and it idles at 1100rpm.i think this is bcoz of the adjustment of the idle screw on the TB.but idle is ok.so im suspecting the obd2a to obd1 harness is the cause...
 
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