What should afr be at idle

You shouldn't really have any unusual dips or high spots, other than the ones explained in this article. Cart 0. Fuel Type; Depending on what type of fuel is used, you may see different mixtures being ideal. For this article, we are focusing on Gasoline oct and our AFR charts are taken directly from a running RB26DETT Camshaft Overlap, Duration; Camshafts with very little overlap, short durations, and gentle ramp rates allow very high vacuum Suction forces to be attained at low engine speeds.

This equates to smooth idle and low engine speed operation. High overlap, long duration and aggressive ramp rates are suitable for high engine speeds as they promote proper filling of the cylinders at high engine speeds - of course this also means that idle quality and low engine speed is sacrificed.

Engines with low vacuum have poorly filled cylinders as well as disruptive airflow in the intake, and thus require more fuel to idle smoothly. Engines can be leaned at idle with no negative effects other than poor idle quality. Engines making high power running lean can lead to melted pistons, knock, blown head gaskets, cylinder wall damage, and all kinds of things you really don't want to happen. It's very important to understand where this limitation is so that we can extract the most power out of the engine without damaging anything, all while remaining fuel efficient.

Knock Threshold; Understanding knock is fairly complex for the typical enthusiast. We won't get into the fundamentals of knock in this article, but we will say that the air fuel ratio will have a very important relationship to the knock threshold on knock-limited fuels. Knock will destroy your engine, without a doubt, so it's important to understand how the air fuel ratio can be used as a knock deterrent. Engine Speed; Engines turning at low speed can run at leaner air fuel ratios than engines at high speed.

This is simply because the engine isn't exposed to as many combustion cycles at lower engine speed as it would be at higher engine speed assuming time is the same in both cases.

Less combustion equals less heat, and thus we may run leaner air fuel ratios without much adverse affect. Engine Load; Engine temperature increases significantly as engine load increases assuming all other variables are constant. Engine Coolant Temperature; Cold engines require quite a bit more fuel to run smoothly. This is mostly due to the fact that fuel atomization is poor at cold temperatures - Fuel tends to want to condense when it's cold, and evaporate when it's warm.

Cylinder Wall Temperature; This is really only important during cold or hot starting. When you read coolant temperature, you are getting a rather delayed reading of the engine's temperature after the heat has soaked through the cylinder walls, been absorbed into the coolant, and then into the coolant temperature sensor. It actually sounds like a pretty good lope and the RPM's bounce back and forth a bit about RPMs , but running stock cams and engine. It almost sounds like too much fuel at idle At idle there is no load.

I don't see why you'd want your bike idling at 13 AFR. I'd shoot for stoich up to That probably sounds more like it It was sitting about until throttle applied. I'll turn the fuel back a bit. Professor Hayabusa Immortal Staff member. I'm about on mine. I have it set where it bumps to about or so at a fast idle for easier warmup. It doesn't gas you out from the fumes under idle that way.

I'm also running leaner Makes a ton of difference in mileage. I believe "stoich" is suppose to be Honda East Justin said:. Click to expand An interesting link I came across Air-fuel ratio - Wikipedia, the free encyclopedia. I think the last time I checked I'm in the 14 range at idle. Could be leaner since there's no load or anything. Your bike should be idling at GSXR-T said:.

The idle is at it's smoothest! The exhaust smell is at it's best. If you have the luxury of a 2 gas analyzer, Some of the various condition will explain on article below.

Before we discuss the air-fuel ratio on various condition, let me first explain about the different types of air fuel ratio on the vehicle. Now that you understand what an air-fuel ratio is and how it can affect the internal combustion process, here we go over what the best air-fuel ratios are for various conditions. When starting your car, all engine components such as the cylinder head, cylinder block, and intake manifold, are cold. Some extra fuel is needed to start the engine in this case so a rich fuel mixture is temporarily needed.

An easier way of describing this is that on older cars with carburetors, the choke was used to block off air so more fuel would be pulled into the engine to start the car. When starting your engine, the air-fuel ratio can be as low as , making it very rich. After startup and while your engine is still idling, the coolant temperature is still low and more fuel than normal is still needed until the vehicle warms up to operating temperatures.

The higher the AFR the leaner the mixture. With We are looking to fine tune an engine to get the smoothest operation. This condition is the most wide open for customer preference based on two factors. This condition is where the peak horsepower value is obtained.