High idle when starting car - soon settles. Issue or quirk?

[mikeyr]

Not sure if this is a 'feature' or sign of a failing sensor somewhere? Leak seems unlikely I think.

Car is a 1.4 petrol Mazda 2 from 2004 (80bhp throbbing through the beast of an engine I believe). No issues with temperature, not using lots of fuel.

Car starts first time and it's initial idle speed is at 1200 rpm, after 2 minutes of driving that drops to between 1000-1100 and then after a couple more minutes it happily settles at around 900 rpm. Turning off air con drops these figures by very little. Genuinely doesn't matter that much but does seem a little high. Am I right in thinking most cars idle at 1100 (at most) when cold? Especially in the current warm weather.

It's had spark plugs, coil, oil and filters done recently so well looked after, would have thought that if high idle was related to any of those items the ECU would have adapted accordingly.

I've not yet put obd reader on car as need to find the bloody thing! I will but intrigued if others think is likely to be a failing sensor? or something else? Once been running for a few minutes is happy as Larry to idle not much over 800rpm.

Edited by mikeyr on Monday 9th May 22:02

[Dogwatch]

Car is 18 years old. Best not to meddle if that is the only problem.

[sunbeam alpine]

Isn't that normal - automatic choke on start-up, which gradually disengages?

It wasn't clear to me whether it happens every time you start the engine (i.e. it shouldn't happen if you restart with a warm engine), but so long as this only happens from cold, I think it's normal.

[M4cruiser]

It's a feature.
If the car is otherwise working then just live with it.

[steveo3002]

wouldnt worry me too much , most cars will kick up the cold idle for a short while

[zedx19]

I had a 2014 Mazda 6 2.2D (newer and different engine I appreciate) but the idle revs would be quite high from cold (sounded like you had your foot on the accelerator!), which was a feature to allow to the engine to get up to temperature quicker, which I believe resulted in a lower emissions during the emission cycle test which resulted in lower VED and crucially, lower BIK tax. As a company car driver at the time, this was welcomed.

Might be the same feature on an older Mazda, revs high to get temperature up quicker.

[mikeyr]

Dogwatch said:

Car is 18 years old. Best not to meddle if that is the only problem.

Inclined to go with this advice (thanks all!). It's occasionally idling at 1000, sometimes at 1200, sometimes at 900 but never rough idle, just seems to vary on a journey so maybe it's just how it runs. Not really an issue and doesn't affect driving so let's just assume all is good!

[Evoluzione]

It's to get the (primary) Cat up to heat quickly to satisfy emission laws.