wat is air fuel ratio??

[seek88destroy]

wat is the usage of air fuel ratio?? and the function of HKS AFR....i have a hks air intake....is it best to have HKS AFR device / or not?

 

[Dino@Casper]

air fuel ratio is not usage.. its a guide of your fuel n air mixture.... the normal ratio would be 14 air molecule to 1 fuel.. thats about the normal ratio during lower revs and lower loading.. as the loading increase normally we would have to lower the air fuel to prevent knocking

 

[Doink]

AFR meter is for those modified cars only..standard cars no need...

 

[trex92]

yes, as mentioned by dino, on what is air flow ratio. The HKS AFR's function is as a meter. We can get a piggyback system that "bluffs" the car ori ECU into thinking a EFI engine needs more petrol hence inject more. In every EFI car, the ECU has a mapping that plainly states if got X amount of air, then inject Y amount of petrol. So what the Apexi SAFC and AFC series does is that it intercepts the signal from the air flow sensor to the ECU so that it can "bluff" the ECU that when actually X amount of air is taken in, the signal to the ECU is Z amount of air. So the ori air fuel ratio is changed by this method.

 

[ping5828]

you hav HKS air intake doesn't mean tat u must hav AFR device lo...
lotsa ppl also use HKS intake withou the AFR and their car also can run.... hehe...

 

[PocketRocket]

AFR is just a mix for combustion between air n fuel...stock car is tuned richer for fuel to prevent knocking n engine blow..however,one can use safc or the AF regulator to maximise the fuel for ur engine...betul ka?

 

[SkYwAlKeR]

air fuel ratio can be usefull as well instead of jz giving u information...
for example; if u can get one wide-band O2 sensor and fix it at ur exhaust pipe, it can work with the air fuel gauge... thus, u can tune ur car A/F ratio accurately without going to the workshop...

 

[nitrus]

air fuel ratio is not usage.. its a guide of your fuel n air mixture.... the normal ratio would be 14 air molecule to 1 fuel.. thats about the normal ratio during lower revs and lower loading.. as the loading increase normally we would have to lower the air fuel to prevent knocking

Oh!! so thats called 'knocking' ? when my car idles, when the load of the fan comes in, the RPM will drop around 200 ... then my car will slightly vibrate n i could hear some sound in the engine bay, i think this is the 'knocking' u're talking about .... is it bad? anything i can do to overcome it? tnx dino...

 

[joshua963]

mine oso same problem lah... i think the timing they adjust to very low ready.. maybe low fuel ratio... not sure... but could this be the problem ??

 

[PocketRocket]

O2 sensor put in the exhaust? now i got a use for my pen-timer...LOL

 

[escaflowne]

Oh!! so thats called 'knocking' ? when my car idles, when the load of the fan comes in, the RPM will drop around 200 ... then my car will slightly vibrate n i could hear some sound in the engine bay, i think this is the 'knocking' u're talking about .... is it bad? anything i can do to overcome it? tnx dino...

this should be ur idling problem that caused the knock.You can hear like metal marble dropping on the floor sound tak tak tak tak..that is knocking..for the example,grab a diesel engine and listen to the engine.You can hear the speacial tak tak tak tak sound.For diesel engine is normal but for our engine it ain't normal.Knocknig actually is precombustion(if i am not mistaken)..Mixture didn't combust when the piston reach the TDC,maybe halfway to it and it combust.Cause excessive vibration and result to the sound of knock.Can be very loud or vice versa,try to rev all the rpm range to listen to the engine sound. Either adjust ur ignition timing or use higher octane fuel to fix this problem.

 

[prodigy]

Oh!! so thats called 'knocking' ? when my car idles, when the load of the fan comes in, the RPM will drop around 200 ... then my car will slightly vibrate n i could hear some sound in the engine bay, i think this is the 'knocking' u're talking about .... is it bad? anything i can do to overcome it? tnx dino...

What he was trying to say is that when you tune the air fuel ratio lower for instance 12 to 1, you risk engine 'knocking' or engine rosak. Our stock engine fuel mapping is about 14 to 1. You run leaner(more air), you save more fuel but you risk having an exploded engine. You run richer(more fuel) means you get bad fuel consumption, more power and lower the risk of engine knocking. However, you run too rich, if your engine can't combust the mixture properly, it means you're wasting fuel. So you need te tune to the perfect balance to optimised your engine performance. But why do i say running richer will ensure engine isn't spoilt. The richer the fuel mixture, the cooler the engine runs.

For turbo cars, they normally run a little bit richer as you know how much stress the engine takes at high boost. If you ever have a chance to see an Evo or Skyline or even a properly setup Wira GSR boosting and then changing gear, you will see a puff of brown smoke coming out from exhaust during a gearchange and it shows the incomplete combustion of a air-fuel mixture.

 

[prodigy]

Speaking about 'knocking' sounds, when you hear a tak tak tak sound during idling, it could also be the tappet adjustment. I had quite bad tappet noise and i thought something was really wrong will i sent to the mechanic and he sort of adjusted it. Now its fine. Don't ask me what tappet is, the mechanic just told me so.

 

[nitrus]

this should be ur idling problem that caused the knock.You can hear like metal marble dropping on the floor sound tak tak tak tak..that is knocking..for the example,grab a diesel engine and listen to the engine.You can hear the speacial tak tak tak tak sound.For diesel engine is normal but for our engine it ain't normal.Knocknig actually is precombustion(if i am not mistaken)..Mixture didn't combust when the piston reach the TDC,maybe halfway to it and it combust.Cause excessive vibration and result to the sound of knock.Can be very loud or vice versa,try to rev all the rpm range to listen to the engine sound. Either adjust ur ignition timing or use higher octane fuel to fix this problem.

yes! i think its that sound ... especially at night when i on my headlights without aircond on , during idle ... Wow cool explaination up there! :regular_smile:

So it is bad for the engine la. Argh... So have to adjust my ignition timing to, higher? Wat about the air/fuel ratio ..?

N i noticed one thing, my aircond idle timing off/on is almost the same. like at 850-900RPM .. shud d aircond on idle timing actually be set higher? or its ok?

tnx yeah

 

[Dino@Casper]

okay what is knocking or pinging is actually combusting without spark plug's ignition, diesel's engine are known as CI engine.. where we compress till the fuel ignite itself, this happens when the fuel's flash point has been reach.. there for explosion will happen even without sparking.. in diesel its the way the engine works.. where else in SI engine.. we would try 2 avoid that.. as pre-combustion normally happens way before the engine piston reaches TDC... and that force generated would actually cause a force acting in the opposite direction of motion of the piston resulting in drop of power.. and damaging other internal parts..

Nitrus check ur ignition timing first.. and than see what is the current A/F ratio.. b4 making any adjustments

 

[joshua963]

Speaking about 'knocking' sounds, when you hear a tak tak tak sound during idling, it could also be the tappet adjustment. I had quite bad tappet noise and i thought something was really wrong will i sent to the mechanic and he sort of adjusted it. Now its fine. Don't ask me what tappet is, the mechanic just told me so.

i think it's timing belt.. they call it in short form as tappet or tipet.. i oso not very sure.. but i feel tat's the one..