Is there anything you can do to a fuel map (EFI), to reduce noise? I understand OEM have peaks and troughs in a map, for both emissions and noise. Can we do the same?

I have the oppurtunity to make any changes to my map before SVA next week, and just wondered if a leaner or richer burn would be quieter?

With direct injection engines, petrol or diesel, you can make relatively pronounced changes to noise by altering injector timing. You may be able to have some effect on a port-injected engine but assuming it was running properly to start with it probably wouldn't be that much. I would expect spark timing to have more effect if anything.

Ahh that could work too. I can control both fuel and spark right across the range.... So would you advance or retard the ignition to reduce noise? This is only at idle, so I would hope either way if is fairly engine friendly...!

You'd be better just playing, I don't think you could definitely say whether advancing or retarding would be best.

Surely it doesn't matter what it is at idle, the noise test is done at 3/4 of max power RPM?

Sorry, forgot to engage brain. I meant it is at no load, so should be engine safe....