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Discussion Starter #1
My 2011 Corolla S has been dropping RPMs when I come to a stop with the AC running like it's about to stall. I'm assuming this is when the clutch engages. I also notice my brake pedal drop a little. What could be the problem? Refrigerant level is normal, had it checked out at a shop.
 

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05 camry 07 tacoma
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What is the idle RPM without a/c and with a/c in park foot off brake.
 

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Discussion Starter #5
Idles at 800 rpm with ac off and and just under 800 with ac on in park. When driving on a hot day and the ac is on when I come to a stop it drops to maybe 500 to 600 rpm and feels like it will stall for a second.
 

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2010 Corolla Altis XRS
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Where is the PC valve located?
"S" model would have the 1.8 liter engine. The PCV valve would be located on the valve cover....very close the the throttle body. You'll need a combination wrench to take off.
 

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Verify if idle drop happens with foot on/off brake.
Hot day ac on in park foot off brake .
 

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09 Corolla Base 17 Camry SE
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Where is the PC valve located?
PCV valve is underneath the intake manifold. Took me about an hour to replace it. Much easier if you can get a helping hand to hold stuff out of the way at times.
 

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"S" model would have the 1.8 liter engine. The PCV valve would be located on the valve cover....very close the the throttle body. You'll need a combination wrench to take off.
Actually you can just look it up in YouTube....under Corolla PCV replacement.....it takes all of 8 minutes to replace
 

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Actually you can just look it up in YouTube....under Corolla PCV replacement.....it takes all of 8 minutes to replace
Note....in the YouTube video....the guy takes the coil pack clips off......no need to as he was using a cresent wrench....just use a 19mm combo wrench and itll take you about 4 min to change out.
 

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Idles at 800 rpm with ac off and and just under 800 with ac on in park. When driving on a hot day and the ac is on when I come to a stop it drops to maybe 500 to 600 rpm and feels like it will stall for a second.
It happens the same to my 2013 Corolla S. If I shift the car to N, then the RPM go up again! I would try to replace the PVC valve but it does not show me any codes! If you change it let me know how it worked for you because I'm considering changing it as well.
 

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Based on what I have read on this forum, and some other resources about Toyotas, at least 80 % of rough iddle when stopping at red line is caused by a bad head gasket, this is a very common issue at 2ZR-FE Corolla's engine, my advise is to perform a compresion test, which most likely will fail in at least one of the 4 cylinder, mine had 125PSI at cylinder 3 and was rough when stopping at red line or from time to time when driving.

Head gasket and other gasket when you opening head MUST be replaced to fix this problem.

PLEASE make sure that only an authorized and knowledgeable mechanic performs this type of repair.
 

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if find this a bit perplexing as the rough idle existed even in new models 10 years back. Mine does a low idle (5-6 hundred rpm) occasionally (like a lot say, in reverse, with headlights off) but it still performs very good, like new.

not sure there would be a point in testing the headgasket for that occasionnal shutter !
 

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I think a bad head gasket exacerbates the rough idle problem which seems to be pretty common. The first thing to do would be to take care of regular maintenance items such as spark plugs, pcv, clean MAF and throttle body. If that doesn't help or if you have other symptoms like pinging or a miss then do a compression or leak down test before you spend any money on sensors, etc.
 

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Based on what I have read on this forum, and some other resources about Toyotas, at least 80 % of rough iddle when stopping at red line is caused by a bad head gasket, this is a very common issue at 2ZR-FE Corolla's engine, my advise is to perform a compresion test, which most likely will fail in at least one of the 4 cylinder, mine had 125PSI at cylinder 3 and was rough when stopping at red line or from time to time when driving.

Head gasket and other gasket when you opening head MUST be replaced to fix this problem.

PLEASE make sure that only an authorized and knowledgeable mechanic performs this type of repair.
I don't buy this as this has been an issue on many cars even when new. It might make the problem worse on older cars but the head gasket being bad hasn't been a huge issue.
 

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If you are feeling a shaking or vibration in gear with the A/C on at idle it maybe broken engine mounts.
 
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