QUESTION on A/F reading

[SkYwAlKeR]

yup,i agreed that u can't use the narrow band to tune ur car but to be frank,sometimes when u look at the reading on a narrow band o2 especially the 4 wire one,u will see that it's not far from the wide band reading.narrow band o2 on our car is to determine how much fuel been injected to the engine to retain optimized air n fuel ratio.narrow band o2 just roughly calculated the heat generated at ur exhaust.the higher the temp,the leaner ur engine burn n vice versa.wide band are more accurate that's why all tuner use it to tune high hp car. sorry for the misunderstanding sky n kennethfong.....:_:

yeap... thats what i'm thinking off.... when engine warmed up and u are driving steadily, does narrow band O2 sensor give a more accurate reading compare to idle rpm??... if the accuracy while driving is abit off compare to wideband O2, good lor... i can alwiz take the effort and drive around to monitor my AFR before retune it again... not necessory to idle and stay there to do tuning...

so, if exhaust gas is hotter, means lean mixture... if cooler, means rich mixture... okok... currently i'm tunining my carbie by feeling the exhaust gas... if got petrol smell or black smoke, means rich mixture... but for lean mixture i dunno whats the symptom....

sky,

if i remember this correctly, cipan supercas in ZTH DIY forum posted a link for DIY Wideband device, u can try that it's quite cheap too (eerh i haven't tried so no guarantee)....

icic... mayb during sioc yumcha i ask him more about it la... thanks for the info....

 

[D-IV]

Its normal. Why i say that is because its due to your old O2 sensor, why'd I say old? you said, engine was put in few days ago which i assume has undergone an engine transplant. Unless the A/F number doesn;t show up at all even though during driving, then i think its your wiring.

I've wired up a few cars already and usually new cars will show the A/F value under 1 minute of warm up (new O2 sensor y0). Hope that helps

 

[Choon]

yup,i agreed that u can't use the narrow band to tune ur car but to be frank,sometimes when u look at the reading on a narrow band o2 especially the 4 wire one,u will see that it's not far from the wide band reading.narrow band o2 on our car is to determine how much fuel been injected to the engine to retain optimized air n fuel ratio.narrow band o2 just roughly calculated the heat generated at ur exhaust.the higher the temp,the leaner ur engine burn n vice versa.wide band are more accurate that's why all tuner use it to tune high hp car. sorry for the misunderstanding sky n kennethfong.....:_:

the o2 sensor is just using the heat of exhaust? are u sure? not that the o2 sensor is detecting how much oxygen is left at the o2 sensor? and the volume of o2 affect the voltage output of the o2 sensor, no?

according to my knowledge, not necessary lean mixture will be hotter.. only to a certain degree. if the mixture is far too lean, the extra air (oxygen) will not be used to combust and this unused air will rob heat from the combustion process, thus lowering the combustion temperature.. correct me if i'm wrong.

i also like to noe how does this auto timer determines afr coz i wanan get one too to monitor my afr, i just need to confirm from wat signal this auto timer gets it's signal to determine afr. my car oni wira NA, so the timer is not really my main point, hehe.. i want the afr reading oni..

 

[SkYwAlKeR]

yea... o2 sensor is located at the extractor... den u expect it to be at the intake manifold there??...

if mixture far too lean, engine die oledi loh...
fuel has cooling effect... try rinsing ur hand with petrol, it feels cool... this helps reduce the engine temperature when running rich... this is because there are somemore unburnt fuel which soaks up the heat from the engine and dispose it thru the exhaust...

i guess autotimer gets its signal from ur car ECU....

 

[Choon]

yea... o2 sensor is located at the extractor... den u expect it to be at the intake manifold there??...

if mixture far too lean, engine die oledi loh...
fuel has cooling effect... try rinsing ur hand with petrol, it feels cool... this helps reduce the engine temperature when running rich... this is because there are somemore unburnt fuel which soaks up the heat from the engine and dispose it thru the exhaust...

i guess autotimer gets its signal from ur car ECU....

ya i noe O2 sensor at the extractor thr, but since it's saying 'theoretical air fuel ratio' so i dunno wheter it tap the signal from the intake or exhaust. if from exhaust, sure it will show the exact air fuel ratio wat.. then if taken from the intake, then reading can only be obtained thru calculation, so maybe the 'theoretical' term comes from thr :p

yep, i totally agree wit u.. too rich will have cooling effect.. the same goes to too lean..

 

[SkYwAlKeR]

ya i noe O2 sensor at the extractor thr, but since it's saying 'theoretical air fuel ratio' so i dunno wheter it tap the signal from the intake or exhaust. if from exhaust, sure it will show the exact air fuel ratio wat.. then if taken from the intake, then reading can only be obtained thru calculation, so maybe the 'theoretical' term comes from thr :p

yep, i totally agree wit u.. too rich will have cooling effect.. the same goes to too lean..

:hmmmm: u've seen cars with o2 sensor at intake manifold??... what engine is that??... :hmmmm:

intake manifold sensor is usually MAP (manifold absolute pressure) sensor... it takes reading on the amount of pressure in ur intake manifold... similar application with vacuum meter... MAP signal is needed to assist the ecu in calculating the exact needed fuel to be pumped into intake manifold...

as for theoritical theorem on what o2 sensor actually measures, i not vr sure... but o2 sensor output signal is 0-1v (for narrowband sensor) and 0-5v (for wideband sensor)....

 

[Choon]

hehe.. i'm not sure how the system works.. now i noe ad.. ;p