AF ratio

[WhiteFinish]

Could somebody explain the air/fuel ratio's?? With the widebands you can read what the a/f ratio is

But how does it help you?

What should your af ratio be when engine is idle
What should it be when cruising at certain speed
What should it be at wot?

Thanks

[solo_ryder]

Could somebody explain the air/fuel ratio's?? With the widebands you can read what the a/f ratio is

But how does it help you?

What should your af ratio be when engine is idle
What should it be when cruising at certain speed
What should it be at wot?

Thanks

It helped me determine I need another ECU as it was running too rich.

IIRC:

Idle for me was about 13-15 A/F But sometimes dips really low - When I was running a KL36 ecu, it would randomly drop to 10 A/F and the car would shudder. That is why I determined I needed a chipped ecu, which fixed the issue.

Cruising was like 14-16 A/F
WOT was around 12-13 A/F

[colinf004]

I have a kl36 ecu for my kl-de.. is it recommended that I should get it chipped for better performance?

[wytbishop]

http://en.wikipedia.org/wiki/Air-fuel_ratio" onclick="window.open(this.href);return false;

AFR is the mass ratio of Air to Fuel in the combustion chamber. For most cars, the ideal AFR is 12.5 - 14 or so. Greater than 14 is lean and less than 12 is rich. The "Stoichiometric" ratio is the ratio at which all available Air is consumed in the combustion reaction.

Knowing the AFR is important because at lean mixtures the engine can be damaged and at rich mixtures it will usually run poorly.

[marcdh]

I'm running super rich, like 10-11 WOT. Probinator chip in a k8 ecu Oh well megasquirt soon

[onlytrueromeo]

Wow, didn't know the probinator was that bad. Might explain why I only get 26mpg highway.

[marcdh]

I know! Same mileage I'm getting dude Maybe something's up, though my o2 sensors are quite new and no codes. I guess I'll find out if the MSnS increases mileage loads! I think my misfiring at 6.5k+ might actually be down to being SO rich.

I've installed an AFPR and dropped the pressure a few PSI , and it hasn't missed again - yet. Haven't had a dry day to put those revs down though. WOT was literally 10.1 before the PSI drop

[onlytrueromeo]

I havn't misfired much except on the first really cold morning (5 degrees F) and some dry gas cleaned that up. I'm running 93 Octane fuel too. I know my VRIS isnt working, and I have a few other issues but I look at Jesse's numbers and he gets 30-33. I know how to drive for efficiency as I was able to get my DOHC RS up past 40mpg on the highway.

[nos92mx3]

Could somebody explain the air/fuel ratio's?? With the widebands you can read what the a/f ratio is

But how does it help you?

What should your af ratio be when engine is idle
What should it be when cruising at certain speed
What should it be at wot?

Thanks

Af ratio should be where the engine will idle smoothly but not overly rich. My car idles comfortably at 16-1 afr
crusing and under light load is basically the same idea lean, but not overly lean, id say crusing at a constant rate of speed, say 55 mph shoot for 14.7 (the stoichmetric rate for gasoline, up to 15-1, possibly leaner but i wouldnt try it without being able to detect knock and alter timing)
WOT rich best torque is made at 11.8-1 , lean best at 12.3-1.

[fowljesse]

I havn't misfired much except on the first really cold morning (5 degrees F) and some dry gas cleaned that up. I'm running 93 Octane fuel too. I know my VRIS isnt working, and I have a few other issues but I look at Jesse's numbers and he gets 30-33. I know how to drive for efficiency as I was able to get my DOHC RS up past 40mpg on the highway.

Just thought I'd mention that I use 2.5oz. Acetone per 10 gallons of gas for 1-3 more mpg.

[onlytrueromeo]

Yup! I know that! But I should be getting better MPG than I am currently getting before going to acetone.

[WhiteFinish]

Is it normal the AFR will change all the time?

When i'm just cruising when engine is normal temperature and just normal music level on my afr will change all the time between 14.7 and 15.5

[Daninski]

Hey how do I measure that. Do I need a specific instrument?

[Flyer]

Hey how do I measure that. Do I need a specific instrument?

A wideband O2 sensor and an A/F gauge...and a cookie.

[wytbishop]

What does the cookie do?