I have an air fuel ratio gauge in my car. It jumps around between 13 and 17.....every now and then i get an LE which i assume means lean.....can someone tell me if this sounds about right

It does depend on the fuel and the behaviour of the engine
But the air fuel ratio should be 14.7 parts air to one part fuel

Is it usual to jump around so much. It bounces from low 13's to high 16's 2 or 3 times a second. The average would probably be high 14's but it never sits steadily at a specific reading.

It never has standard unleaded so 97 to 99 ron.engine is running fine with no symptons that it might not be running right, i just wanted to make sure the gauge reading isnt something i should be concerned about as maybe an early sign of an issue

I don't about your specific gauge as being that jumpy is not awfully helpful
To accelerate the throttle allows more air in, which is metered and then the Ecu puts more fuel to compensate
As the engine settles the mixtures fluctates

Cool......thanks for that. That sets my mind at rest a little. I might get it looked at just im case.

Cheers for your help

Just remember, when you're coming off throttle, no fuel is injected so this is probably triggering the LE you mention

I took it out this morning and it does onlu LE when i come off the throttle so sounds like all is good.

Finally got the dream mint coupe so the paranoia is starting to kick in i think

Sounds normal. It's only reading from a narrow band sensor so it's not exactly accurate outside of the very specific ideal ratio and it'll naturally bounce up and down around that ratio as the ecu adjusts fuelling

With a new sensor it'll cycle up/down more than once a second, with an old sensor it'll only cycle once every few seconds.

That's why on my old install guide I recommended installing the gauge out of direct sight behind the wheel, as it can be quite distracting at night.

Mines in a pillar pod 😀