Jump to content
SAU Community

Recommended Posts

hey all!! :ermm:

could someone please enlighten me on how an air/fuel gauge works?

ie: where does it take its readings from?

why does it sit on 14 under acceleration and at idle but when backing off moves upto 18 and hangs there for several seconds or until i accelerate again and it moves back to 14.....

cheers guys..

Link to comment
https://www.sau.com.au/forums/topic/118161-airfuel-gauge-how-does-it-work/
Share on other sites

howstuffworks.com gave me a basic insite into O2 sensors. but id still like to know what its actually reading..

im guessing when the needle moves up over its optimal point its registring excess oxygen in the exhaust but when it moves below is it registering an excess of unburnt fuel (lower oxygen ratio)...

any tuners out there ??

i took this from this link Cheaply Monitoring Air/Fuel Ratios. i'm building the jaycar air/fuel mixture kit at the moemtn and the instructions that come with it have a fantastic explaination of the air/fuel mixture gauge.

All unleaded petrol cars use an exhaust gas oxygen sensor. As the name suggests, this sensor is mounted in the exhaust flow - usually in the exhaust manifold - and sniffs the composition of the exhaust gas. Specifically, it measures the ratio of oxygen in the exhaust gas with that in the atmosphere. It does this is to determine whether the air/fuel ratio is rich, stoichiometric, or lean. The ECU uses this information as part of its self-learning technique, . . . The most commonly used sensor generates its own voltage output, which varies between 0-1 volt. In round terms, if the sensor output is about 0.2 volts or less the mixture is lean, and if the output voltage is over 0.8 volts it is rich. However, the precise value of the output voltage is less important than its relative value - whether it is "richer" or "leaner" than the mid-point voltage.

The ECU constantly adjusts the mixture depending on the driving conditions. ie. if you are accelerating, you require more fuel in the mixture so the ECU tells the injectors to inject more fuel and resulting in a richer mix. if you're backing off, its just the opposite.

hope this helps

Edited by vannic

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • I don't understand how this hasn't boiled down to - Upgrade the turbo when you have everything required. ECU, injectors, fuel pump, turbo, etc. Do it all at once.  If you don't have everything required, just enjoy the car as it is and keep saving up your pennies. 
    • Sounds like you've got an interesting adventure ahead here with local support if you have trouble! My guess is that, unboosted, you will be OK with a small upgrade like -9. What will happen is that once the stock ECU sees more airflow than it expects it will add a heap of fuel and pull a heap of timing to be safe because it can't understand how it could get that much air without there being an issue. You will see clouds of black smoke and it won't pull hard through the midrange and top end. So, overall it will be a bit frustrating but should be OK. If you are still nervous set the base timing back 2o through the CAS, but it will be even more sluggish everywhere. As said above through...this is not my guarantee your engine won't be blown into a million pieces, leaving you looking for very hard to find parts A better idea is get a computer with logging ASAP, wire in a wide band O2 sensor and a use remote tuner. I've done multiple cars this way and while it is not as good as a specific tune on a dyno they can get it 90% right. I'd suggest if you can afford an R33 GTR these days you can afford an ECU and tune. And if you can't afford that you sure won't be able to afford the rebuild if it goes bad in the meantime,.  
    • Yeah it would be nice if someone took the time to put that sort of information together, but there are a lot of variations in looms. I think you are making this way hard for yourself if you just want to get it running....sourcing an SR20 with the right wiring will be a billion times easier than matching the RB loom to an S15 chassis. If you do end up going this way, you just need to trace every wire in the loom with a multimeter, 95% of them will go to a location you can confirm at the ECU.....and then post it up for the next person who needs it  
    • Just top it up with water, and keep a general idea of how much you added. It is normal for water to be pushed into and pulled out of the reservoir through the cap, and it should not be more than half full or it will be likely to overflow when hot. Any decent mechanic can do a pressure test of the cooling system to confirm if you have a leak. Keep in mind if it is only leaking a little and when hot it may well evaporate before you see it hit the ground
    • I'd ask the shop what they used and use that. Mixing coolants is sometimes OK, sometimes not, and you have know the details of each coolant to know whether it's a good idea or not.
×
×
  • Create New...