Rough Idle ?(not a repeat, promise!)

[Patrick.VA]

Hi all,
My 2011 CXL has a rough idle and my OBD link app shows my RPM level fluctuating(Dash Command rules! It's way more accurate than watching the needle for tiny movements) I've had the car throw a P0300 random misfire code(which cleared right away) and I worry that this could be the beginning of something.
So far all I've done is clean my throttle body with the proper spray cleaner.
My searches both here and around the internets results in having, in no particular order, timing chain, faulty spark plugs/wires/coil pack, weak battery(?), fuel pump/filter, etc. The one that got my attention is that the Idle Air Control could be sticking.
I'm embarrassed for asking because I am no novice to automotive repair, but where the heck is this thing? Do our Regals even have one? Has anybody had a problem with theirs? Thanks ahead of time for any guidance.
-Patrick

 

[MelsRegal]

looking at autozone and advance I see no IAC for your vehicle. Timing chain would start making noise. No mention of mileage and whether normal maintenance of filters and plugs?

 

[Walt G]

This engine does not have an idle air control system. The main electronic throttle, plus spark timing adjustments, are used to control low idle speed.

What I would do (take it or leave it... I'm no expert on this particular engine):

1. If this is happening all the time: check for vacuum leaks and check the spark plugs (no spark plug wires on these engines either... coil-on-plug design).
2. If this only happens rarely, I don't think vacuum leaks or ignition issues are as likely, as they tend not to be intermittent. If I can't find a vacuum issue or obvious ignition issues, my experience with GM engines that have variable valve timing systems is that those actuators often cause bad idle performance and don't tend to throw anything but misfire codes (side note: I don't know how ARB let them get away with this). Change the oil, put in something 'good' (don't mean to presume that you have not been doing this already), and see if it cures the problem (the cam phasers are oil pressure driven).
3. If I get past 1 and 2 above and that doesn't solve it, I'd be at a point where I'd need some help. There are specific tests to check if the issue is spark, fuel or mechanical related, but you'd need a proper GM service tool to run those. If I didn't know someone with a GM service tool, I'd be headed to the dealer or a good mechanic just to have them run the diagnostics tests. Then I'd follow the appropriate troubleshooting path from there.

Good luck.