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Discussion Starter · #1 ·
First 1500km I had issues with my MG3 Auto Core3 (I’m in Australia) with noise from the motor (tapping) and occasional shudders.

Brought it in for my first complimentary service and they asked what fuel I was using

I told them Unleaded 91 (which is what is displayed inside the fuel cap cover)

The Service team said I needed to run it on Unleaded 95 (which is about 20c per litre more expensive)

So I switched to the higher grade fuel and the issues went away

My question (gripe) is why wouldn’t MG just advertise that the car needs that fuel type from the beginning? Do they think it would scare off new buyers?
 

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Not sure how those ratings translate to UK as the scales might not be the same but if it says 91 on the fuel cap then it really should run okay on it. I would be looking at the dealership (guessing it's new from what you've said) to remap it (for free) for that fuel if I was in that situation.
 

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'Pinking' occurs because the flame spread is too fast, the higher octane rating slows it down. Because the spread is too fast, it detonates before it should, and the engine tries to run backwards. If ambient temperature is high, this makes things worse, so in cooler climates, it would run ok on the lower octane rating. If it was an older car, you could add octane booster / parrafin / white spirit / diesel to slow the flame spread, or retard the ignition by 2-3 degrees, but on yours, just use 95 octane.
 

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Discussion Starter · #4 ·
'Pinking' occurs because the flame spread is too fast, the higher octane rating slows it down. Because the spread is too fast, it detonates before it should, and the engine tries to run backwards. If ambient temperature is high, this makes things worse, so in cooler climates, it would run ok on the lower octane rating. If it was an older car, you could add octane booster / parrafin / white spirit / diesel to slow the flame spread, or retard the ignition by 2-3 degrees, but on yours, just use 95 octane.
wow, I can't say I understand most of that but yes, will use 95 moving forward ;) thanks for the reply
 

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Not sure how those ratings translate to UK as the scales might not be the same but if it says 91 on the fuel cap then it really should run okay on it. I would be looking at the dealership (guessing it's new from what you've said) to remap it (for free) for that fuel if I was in that situation.
yes, its new. what does 'remapping for that fuel' mean?
 

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The computer adds fuel where needed, and retards the ignition for the lower octane rating. Ask the dealer if they can remap it for you, but you may need to go to a tuner to get it done.
yes, its new. what does 'remapping for that fuel' mean?
you don't need to go to a tuner to remap it, just download the ''Rover MEMS'' app in your phone or tablet and get a usb to obd2 cable to connect your phone to the obd port. Then you can use the app to retard the ignition. You can also change the air fuel ratio to pass inspection or make it idle faster or slower. It's very simple and intuitive, it's just a slider that you slide to control the values. Just make sure you do it little by little, and if you screw up just return to the factory settings. Great app 10/10
 
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