Idle changing with Elevation?

[SpenceRx]

I just picked up my car from Alberta and drove it around for a couple days in town. It was idling at 1200 rpm which I thought was a bit high.

The car was tuned in Calgary at an elevation of 1,048 meters (3,438 feet) above sea level. Now in Vancouver at sea level and the idle has been consistently 750.

Is this related to the elevation change or is something else going on here?

[EC900]

I’ve read that altitudes can affect performance - air being too thin and performance will lag. I don’t think 3500 ft is considered high altitude.

So when you began your return trip, you had that 1200 rpm idle?
Any shakes or roughness now at 750 rpm?

Take a look for obvious vacuum leaks then
I’d try and tweak the idle back to recommended 950 at operating temp. and see how it goes before any dabbling with mixture setting.
Then it will be on to the other CIS factor’s.
Read this link:

https://cis911primer.com/pages/test_troubleshoot.html

[SpenceRx]

Thanks for the link and sage advice. I’ll do some reading. Seems to be running pretty well but maybe a bit rougher.

[pmax]

Probably idling a tad richer at sea level.

Not sure about the 77 but some WURs have altitude compensation built in.