ecupro

Wonder, Wira 1.6 Auto. This engine did not have o2 sensor for close loop. When tunning, they only allow to adjust the VR,variable resistor ( Lean or Rich ). My question is, how the stock ecu know that the a/f in range ( 14.7 ) ?
Those who drive on Toyota, SEG ( Malaysia ), also do not have o2 sensor. Only VR to adjust. How they do that ?
Any Si fu.......
Thank you.

     

nova

No closed loop, no need loh.:regular_smile:

     

dolly

take a few of the same engine (perhaps hundreds or thousands). Run them on the same map and figure out the distribution. Alter fuel map to accomodate MOST of the motors, apply compensation for barometric pressure and temperature.
Keep ignition timing at a very conservative value so nothing blows up (and allowance for lower octane rating fuel)...

my 2sen, and how i would have done it xD

     

cuscostrutbrace

i think they have the CO instrument fitted to the exhaust when tuning the VR

     

Useless

ecupro,

u the sifu la....

my poor 2 cents assumption....
factory obtains economy and power maps (assumed 2 maps) under testing conditions. hence there is a need to determine the point of switching between these two maps. i think the <TPS> and the <actual indicated airflow> would be the determining inputs. to ensure that the output is achieved, a gas analyzer would first need to be used to preset the CO output from the VR screw. i believe that only after presetting all base points, only can desired results be obtained. Just as we need to preset the ignition timing for the ecu by the strobe lamp for older generation cars before we can obtain optimum torque.

sorry if i am muttering nonsense :P

cheers.

     

e819

co2 sensor??

     

ecupro

Well, to make this more wonder, like joeker say, stoich( 14.7 ) at idle, lean at cruising and rich at WOT.
My wonder will be, how the ecu know that you are cruising ( engine run on lean )!
How They Do That ?

     

dolly

if map based, then based on the load (pressure) seen. if afm based, well then based on the volume of air entering. Either that or tps based

     

ecupro

Bro, most ecu have loading feed back sensor (Map,Hot-Wire...Tps....)
In this case, only don't have o2 sensor.
When come to cruising, how the ecu know that you are cruising ? ( lean on engine ) How They Do That!

     

Useless

sigh...

my assumption...(at per instance)

condition 1:
if tps=30%, airmass=30kg/h, ecu to output "lean map"

condition 2:
if tps=30%, airmass=20kg/h, ecu to output "rich map"

makes sense?

rgds

     

ecupro

Si Fu Brian, I think the air mass flow wrong lah.
If air mass flow more air, the volume should be more, right! ( 30kg/hr , and not 20kg/hr ), in this case, more fuel will be added.( Rich )

Correct me if i am wrong, Si fu Brian, where are you attach to ? Look time did not see you!

     

Useless

correct me if i am wrong sifu leow...
if we are at crusing speed (lets assume TPS=30%), the airmass would always be at a fixed value (lets assume 30kg/hr, with maybe +/- 5% tolerance due to other external factors i.e air temp, baro press, coolant temp, etc).

if we jab the throttle instantaneously (lets assume TPS=30%), the airmass would not be 30kg/hr, not will it fall in the tolerance of +/- 5%. i might be wrong here to say airmass is less (at the instance), i am thinking that the sudden opening of the throttle valve decreases vacuum in the manifold. therefore airmass is less? Or maybe as long as the airmass measured has a great positive or negative difference from 30, then output is extra fuel?

but i am thinking again maybe the Wira 1.6 Auto is more straight forward. The VR just increases or decreases the multiplication factor for fuel. Therefore setting it correct at idle will have a high chance to produce close to 14,7 at light driving conditions.

i am working in KL now. sent u a short PM. yes long time no see. will contact u if i am heading up north to ipoh.

regards

     

cuscostrutbrace

Sifu..

The ecu knows the car is cruising from the sensors,vehicle speed,rpm and manifold pressure.If this 3 parameters is deviating not more than 5% or stays constant for a certain period of time,the ecu assumes the car is cruising and enter closed loop leans the mixture a bit.

If sudden throttle opening,accel enrichment comes in thats why it becomes rich for a certain period or time (or rpm) and decay after that.Then if the 3 parameters stabilize again,the cruising mode comes in..

The time in and time out determines how fast the ecu go into closed loop and start leaning the mixture during cruising.Thats why short trip increases fuel consumption .

correct me if i'm wrong

     

Maxx

hm.. my engine doesnt have o2 sensor too.. turbo summore.. hahha :_:

     

ecupro

cuscostrutbrace,
No bad at all, you are upgrade to Si Fu level.....ha..ha..ha
Time is very important factor.

     

Useless