Engine bogs at an idle

[bankrobber]

2007 with 5 speed and 80K miles.
I have noticed at an idle about once a minute it the RPM's will bog way down so I can feel the car shake. Most times I was running A/C and thought the compressor was the cause. I have had the same problem today with using my heater. Only maintenance done to car has been oil changes, air filter, Transmission fluid changed. What causes this?

[schleppy]

My 09 with 15k on it does the same thing occasionally. Not so much that it causes an issue, but the idle dips. From what I've read (and from past cars), it's not uncommon at all, especially with the AC running.

[bankrobber]

OK, thanks. My last car was a V-6 so I am new to the economy cars

[Doc Zaius]

Mine does it too... always has... always when the A/C compressor turns on. Oh, and your A/C turns on by itself if you're using the defrost (even half defrost, half feet). :thumbsup:

[auxmike]

I have had the same problem today with using my heater. Only maintenance done to car has been oil changes, air filter, Transmission fluid changed. What causes this?

Heater set to defrost mode will kick on the A/C, thus pulling down the RPM's again.
I hate that feature....:mad:

[yaris2010RS]

OOOOOOOOOOOHHHHHHHHHHHH, lol, thats what it is, lol. has anyone had the problem at idle (mine idles about 500-600RPM and randomly it will rev up to about 750-800 and hold for 30seconds and die back down? i only have 1,500km on it but its kinda random.

jsut a side note, i was looking at the engine to try and figure it out, as soon as the engine revs up the fan turns on, and as soon as the fan turns off the revs go down. i'm assuming this has something to do with alternator or a power issue?

[talnlnky]

engine is trying to find the minimum rpm level that it can sustain without stalling... thats all it is. so your car is trying to lower the idle... but then shudders... and ups the rpms again... Not an issue unless your car start turning off when it does this.

[yaris2010RS]

has anyone noticed the fan turing on and idle jumps up till fan turns off? and i find the car can idle at about 550 no problem, not shaking too much or anything. but then the fan turns on, lol