closed loop anormal variation

hondapowaa · Post by **hondapowaa** » Mon Feb 09, 2009 10:16 am

Hello,
(first scuse for my english, i'm french lol ^^)

When i put my ecu with the s300 in closed-loop mode, the ecu/hondata don't stop do move between the minimum and the maximum short term adjustement.
(example => instead be stable (after adjustment) @lambda 1, this always move between lamda 0.8/0.9 and lambda 1.1)
But for the national cheking i must be between lambda 0.97 and 1.03

As i know the normal opération is ecu/hondata will adapt injection to match the target lambda voltage (by using short term adjustment) and when the correct value is find (and trottle is stable) it stop any change, i'm right?

This make when i want to check nocive emissions(co) of my car for the national cheking(obligation) my emissions are not correct. (cause the lambda move too much)

-My s300 is in a P30 JDM(obd1)
-i try with my oem narrowband and my innovate wideband set like a standar narrow. result is same.

Can you help me a little or tell me if a real closed loop mode is impossible with the s300??

thank you very much!

Alain

Post by **Spunkster** » Mon Feb 09, 2009 11:28 am

What vehicle is this in? Closed loop operates just as it would on any OBD1 ECU. It sounds like this is more of a tuning issue if you aren't reaching the desired AF ratios.

hondapowaa · Post by **hondapowaa** » Mon Feb 09, 2009 11:36 am

Spunkster wrote:What vehicle is this in? Closed loop operates just as it would on any OBD1 ECU. It sounds like this is more of a tuning issue if you aren't reaching the desired AF ratios.

it's on an b16a2 modified(stage 2 cams /ek9 pistons etc)

Why when the lambda "1" is matched, the corection/adjustment don't stop(or just move the minimal needed) but continu to move from the min/max ???

(always move from 0.1v to 0.9v and reverse but never stop to 0.5volt which is the "perfect" lambda value)

(as i know with the oem obd2b ecu, thi closed loop mode is more stable..)

Post by **Spunkster** » Mon Feb 09, 2009 1:48 pm

The operation of a narrowband sensor as it's name indicates. It operates in a very narrow range of voltages for stoich operation. The voltage will swing back and forth and as long as the average at 14.7 then there will be no trim adjustment.

hondapowaa · Post by **hondapowaa** » Tue Feb 10, 2009 12:15 am

yes i know this no problem but when the stoich goal is "matched" my ecu/hondata don't stop to adjust but it continu to move like it never find this stoich........

Post by **Spunkster** » Tue Feb 10, 2009 12:22 pm

It always fluctuates back and forth.

hondapowaa · Post by **hondapowaa** » Mon Feb 23, 2009 5:59 pm

hello.

It always fluctuate back and forth min/max but when the target lambda / voltage is reached why this "fluctuate" don't reduce to the minimal needed??

Understand if it always fluctuate min/max then it's impossible to have a strict stable and constant rpm level and gaz emission. (cause one time we accelerate(too rich) and one other we decelerate (too poor))

so what can we do?

Post by **Spunkster** » Mon Feb 23, 2009 6:02 pm

All you can do is tune the engine more. There is no way to change the way closed loop operates.

hondapowaa · Post by **hondapowaa** » Sun Mar 08, 2009 8:46 pm

hello,

In standard, all your calibrations s300 manager contain have
-minimum short term adjustment : -30%
-maximum short term adjustment : 47%

If i understand what you said this signify with closed loop operation active, my injection always move from -30% to +47%?
(not -17% or +25% but always -30% or +47%)

or this signify each correction made to find the target voltage will modify the injection value to -30% (if i'm too rich) or +47%(if i'm too lean)???
(exemple, if after one correction (-30%) i'm once again too rich, the second correction remove once again 30% fuel of the last value, so this make -60% of the original value)
it's correct or not?

Ask you this cause i try to modify this value and i put minimum short term @ -3% and maximum short term @ 7% and i have a better correction.

I think it will really a good idea if we can view and set how many fuel this system add/remove for each itération of the adjustment.

(example, i really wish tell to the program
"you can correct the mapping @ max +/-30% of initial value but proceed step by step @1% for each step. then stop if target voltage is matched")

If i'm right the actual working of the closed loop is not really optimal :(

i must tell you one things :
in open loop @2000rpm (car stopped no gear engaged) i'am @ approximately @14.7afr.
So i'm ok
when i go in closed loop(-30/+47) @ same condition the afr vary approximately from 14 to 15.3.

it's not really good :(

Post by **Spunkster** » Mon Mar 09, 2009 9:45 am

Those numbers are the maximum that it can either add or subtract fuel in closed loop, it is not the variation it uses when cycling it self to achieve optimum mixture.

cranny · Post by **cranny** » Wed Mar 11, 2009 2:09 pm

i know this has been asked most likely.

spunkster or hondata..

why is it that the capability of using an aftermarket wideband for controlling the air fuel ratio in closed loop cant be done here? it would be such an awesome addition and selling feature for the S300. would a hardware modification be needed to achieve this? im assuming yes.

crucian · Post by **crucian** » Thu Mar 12, 2009 3:51 am

Yeh, I tried using closed loop and gave up a long time ago. :(

hondapowaa · Post by **hondapowaa** » Sun Mar 22, 2009 4:44 pm

what i can tell is =>

When in open loop i have exactly 14.7/14.8 afr, with the closedloop activated my afr don't stop to move back and forth example form 13.8 to 15.5.................

What i think is in each cycle, the correction made by the hondata to goal the correct voltage is really too big. the result is one time we are too lean, one other, too rich etc etc etc.

(just an example, if to match we need to injec juste 2ms more but the hondata can correct by step of 5ms we never can match what we want.)

Sincerely i really think the closed loop "module" of the s300 can really be upgraded and receive some améliorations.

Why don't add options that permit to us to set the time correction at each cycle, a minimum target voltage AND a maximum target voltage, and maybe other things?

GTMcoupe · Post by **GTMcoupe** » Mon Mar 23, 2009 12:41 pm

Am I right in thinking you tuned for 14.7 in open loop.

switched to closed loop and now you are cycling between 13.x-15.x with large short term trimming.

WEST

hondapowaa · Post by **hondapowaa** » Mon Mar 23, 2009 1:22 pm

GTMcoupe wrote:Am I right in thinking you tuned for 14.7 in open loop.

switched to closed loop and now you are cycling between 13.x-15.x with large short term trimming.

WEST

Yes it's what i say.
In open loop i'am correct but in closed loop it's chaotic lol... :(