My Corolla 2014 has this issue where revs fluctuate quite a bit at idle, sometimes dropping to 4-500 revolutions and going back up. I changed the MAF sensor, cleaned the throttle body, replaced the air filter, replaced spark plugs, and it still does it. Also, there’s no CEL or codes. I took it to my mechanic and they couldn’t find anything wrong with it.
What could it be?
Check your oil fill cap gasket. Just replaced mine after having weird RPM drops when lifting off the gas and now it’s 99% gone. I had replaced MAF and did the idle relearn procedure but oddly this is what helped. You probably have a vacuum issue.
2010 Rolla 1.8, 150k mi
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