Questions tagged [air-fuel-ratio]

A term describing the ratio of air (available oxygen) to fuel (available hydrogen and carbon) in the combustion process. It is said to be rich when more fuel is available than air and lean when there is more air than fuel.

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Does an oxygen sensor's lambda value represent the same when running on LPG?

I have converted my car to LPG, and i've been tuning it today with a wideband lambda controller. It runs pretty okay, but i'm not yet satisfied. The weird thing is, it accelerated best when the ...
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795 views

Relationship between torque, power, specific fuel consumption, and AFR

How does Torque, power, and specific fuel consumption change with AFR? And why is it so? I found graphs relating these in books as well as websites but I couldn't find any good explanations.I have ...
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176 views

Selecting an aftermarket turbo

I am trying to upgrade the turbocharger on my 2007 Volvo C30 T5 from the stock K04 to something larger and capable of supporting 350-400bhp. I followed Garrett's website which allowed me to generate ...
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1answer
55 views

What actually occurs between the fuel, and air molecules during combustion?

During atomization the fuel still remains in liquid form, it's just broken up into small droplets consisting of multiple fuel molecules. Once this mixture of fuel droplets, and air is inside the ...
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1answer
616 views

What formula is used when deriving AFR/lambda value from emissions?

When you get your vehicle hooked up to a gas analser, you'll see the 4 or 5 kinds of emissions you're interested in, and a lambda or AFR value derived from those emission values. I was wondering how ...
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a/f mixture for 4 cycle brushcutter

Hi I have a ryobi rbc430sbsb 4-cycle brushcutter. When I use brus cutter it seems to start relatively easy and seems to work reasonably well but when switched off it seems to be dumping fuel out ...
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1answer
684 views

Does opening the throttle mean a leaner fuel to air mixture for starting?

As per the title, if I'm starting a motorcycle or lawnmower or something similar with a carburetor and I know the mixture is too rich, does opening the throttle lean the mixture out? I've got a ...
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What's the meaning of a “lean” vs “rich” air fuel mixture

I'm learning about vacuum leaks on engine intakes and I'm hearing this terminology of lean air fuel mixture. I thought I heard of a rich mixture before too. What's a normal mixture referred to as? A ...
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Given that one of the reasons diesel engine produce black smoke is overfueling, why do diesel dragster produce so much soot?

I've read on the internet, in a couple of maintenance books and asked a few buddy mechanics and they all seem to point to the fact that a healthy diesel engine should not produce black smoke and that ...
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3k views

Percent of Air and Fuel used for Combustion

I've had this question for a long time. I know the percent will differ based upon the throttle position and will be either by stoichiometric ratio or rich mixture. The stoichiometric ratio (AFR) ...
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1answer
3k views

Bike currently running rich due to aftermarket exhaust, will adding an aftermarket air filter without any ecu work fix it

I have an MV Agusta Brutale 675 with a GPR Carbonox slip on installed. The air filter is stock and no work has been done on the ECU. My problem is: at this state it's running rich as one can smell un ...
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How to fix P2195, P1172, P1174 and P2197 error code for Honda Accord LX 2004?

Make: Honda Model: Accord LX Year: 2004 Error codes: P2195, P1172, P1174 and P219 Mile: The vehicle was driving for over 6 months Symptom: there was a missing fuse for the A/F ratio sensor heaters....
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948 views

How is AFR calculated from ODBII readings

In another post (A most intriguing cold-start misfire mystery) I found this quote: Mass air flow = 3.66 g/s Fuel flow = 1.27 l/h, Fuel rail pressure = 380 kPa This indicates to me that AFR ...
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1answer
437 views

Is it possible to fit mashroomhead air filter in Honda Stunner CBF 125?

I have Honda Stunner CBF 125 2009 model. I just need to know is it possible to replace the typical air filter with mashroomhead air filter to improve the bike performance? Is there any other way ...
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Why or why not increase engine efficiency by running the car “fuel-lean” (using a turbo or supercharger)?

Everyone wants their cars to use less fuel, right? I read the following passage about running the car fuel lean from this website: Run the engine fuel-lean, that is, use excess air. It is well ...
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361 views

Air / Fuel Ratio Problems relation to Fuel Trims

Wouldn't various A/F ratio problems such as vacuum leaks, low fuel pressure or clogged injectors cause a constant adjustment to fuel trims, first via STFT and then to LTFT? For example, if there is a ...
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Why is cold-start fuel mixture enrichment necessary?

I know a rich mixture is more fuel added than air in the ratio required (14.7:1), but how can it affect anything? I mean, if fuel is added but with no air it can't combust, so how can that affect the ...
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Why does a petrol engine need to maintain an air-fuel ratio, while a diesel engine doesn't?

This simple question has been bugging me for a while. The amount of fuel injected into a petrol engine is calculated according to the amount of air entering through the throttle valve (as measured by ...
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1answer
261 views

JLO Rockwell 2F600

I have an old hovercraft that uses a small aircraft engine in the front to power both the lift and forward propulsion. I was hoping to find any kind of manual or literature on the engine itself. The ...
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3answers
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1996 Ford Mustang 3.8L V6 - Intermittent Stalling on Slow Down/Stop

I am having a rather interesting problem that I can't figure out with my 1996 3.8L v6 with 137k on it. Occasionally, I will experience a problem when I slow down or stop the car just gives out and ...
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2003 F150 5.4L V8 Long Term Fuel Trim High Bank 2

I am currently chasing a lean condition in my Ford F150. My fuel trims were reading high on one bank (bank 2) and I am curious when I find the vacuum leak or whatever is causing the high readings, how ...
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Why do Subarus run so rich under boost

This isn't a general question regarding air/fuel ratios. I want to know why Subaru specifically insists on making their cars run ridiculously rich under boost. For instance, my 2007 Forester XT has an ...
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Oily Sludge in the Intake Manifold

When taking off the throttle body to clean my IAC, I noticed that there was a thick layer of oily sludge coating pretty much everything inside the intake manifold: I have two queastions: How did ...
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Why would one install widebands on vehicles that are setup for narrowbands?

A recent post on one of the forums I frequent has piqued my curiosity. From my limited reading on the topic, widebands do a better job of quantifying air-fuel ratios than their narrowband ...