Irregular idle every 15 seconds or so

[F4Gary]

So was out cleaning up the interior and had the engine idling.  About every 15 seconds the idle would slow a bit with the lower idle shudder, and then recover to normal.  Like is would slow 75 rpm and then recover.

Any ideas?  Haven't checked for a code yet and now light on the dash.

Car runs fine otherwise.

2017 Edge Sport 2.7L

Edited February 2, 2025 by F4Gary

[1004ron]

Was it with a full tank of gas?

[F4Gary]

I don't think so.

[1004ron]

Best get the stored error/fault codes read and that should offer some direction - I'd guess that it's the evap system, but reading the codes is the way to go.

[Got 2]

Did you have AC or defroster on? (The default startup climate settings used to put the defroster on at start. And the defroster is meant to act as a dehumidifier to "dry" condensation on the inside of the windshield as well as melt ice on the outside.) The defroster controls won't show you the AC is on. And the compressor cycles on and off quite often. At idle, that's usually enough of a load to make the engine labour a bit until the throttle catches up to the load.

[vrdublu]

I've had this issue while using 87. Could've also been a bad tank of gas, either way it was on 87. Only using 93 now.