MG ZS ZS11 ZST Excite (2020-2024) Questions & Answers

Hi John Back in ye olde carburetor days, usually with a manual transmission, idle was 600-750 rpm, autos a bit higher. But now both our ZST 1.5l Core and MY18 Forester 2.5l, non turbo autos, idle just under 1,000 so ~900 sounds right. I think that it's to do with both emissions and automatic transmissions not stalling when suddenly loaded moving from neutral / park into drive or reverse. Some cars might have an idle up but if it isn't quick enough the engine might find the extra load too much and even stall. Air con also needs to be considered. Idle up was a feature when it became widely available too, the sudden compressor load at idle being the culprit. When the old double piston reciprocating compressors were replaced by the more efficient modern swash plate ones with 5 much smaller pistons timed at 72 degree intervals the cut in load and fuel efficiency were drastically improved. So, not to worry, all's well with your ZST and enjoy. But if it was mine I'd be using 95RON fuel if you're not already, the turbo causing greater load in the engine due to air being forced in and not sucked in, which is what a turbo does, it being a form of air compressor. There are higher internal loads, pressures and temperatures than normal engines. So much so that regular oil changes are your turbo engine's best friend. The better fuel might lower the idle a bit if Mr Computer says so too. Cheers

That is a very pursuasive response.Thank you very much it has set my mind at rest on this issue.