Rough idle only with A/C on

[A_A_G]

My wife's '08 xB tends to shake violently when coming to a stop while the A/C is on. If I turn the A/C off it goes back to normal. Any ideas what could be causing this? It's at 130k miles and I replaced the plugs at 100k and coils at 115K.

 

[CharBaby]

Could be a worn motor mount causing the vibrations when the A/C is on(idle in gear).

 

[LeakySeals]

Its a small engine, so it will struggle when the AC goes on. If anything is off the engine will shake. IMO Its not idling up under load. Has an electronic throttle body I assume. That needs to be removed and cleaned thoroughly, very simple to do. Also the intake manifold gasket may be going. May as well replace that with the age. Not hard. Check the dog bone engine mount on top of engine if it has one.

 

[mclasser]

Originally Posted By: Char Baby
Could be a worn motor mount causing the vibrations when the A/C is on(idle in gear).

+1 Check the mounts first. Being a 4-banger, some degree of vibration is expected.

 

[OPR4H]

Had that problem in the past, injector starting to get weak coils. Cleaned, no joy, exchanging them was the remedy.

 

[BigJakeChevy]

I had this same issue on my Envoy. Turned out to be a dirty throttle body. Quick clean and ran perfectly after.

 

[spk2000]

Sounds like it is causing more load on the engine than in the past so could be a bearing or other resistance increasing in the AC compressor. Might need a new compressor. I had a car do this when I overcharged the ac and it had to work too hard turning it.

 

[Chris142]

Is the cooling fan coming on with the ac?

 

[Eddie]

Most 4 cyl engines have a feather where the rpm kicks up when the AC compressor turns on. Sounds like that feature is not working. Ed

 

[Trav]

Try cleaning the throttle body especially the IAC you may need to remove the TB to do a proper job. There should be YouTube videos on it.

 

[PimTac]

Originally Posted By: Eddie
Most 4 cyl engines have a feather where the rpm kicks up when the AC compressor turns on. Sounds like that feature is not working. Ed


This.

 

[Silverado12]

From my experience, if the IAC is giving you problems, you're better off replacing it than cleaning.

 

[dblshock]

start running TC-W3 in your fuel steady.

 

[Ethan1]

It's a 9y/o Toyota. You don't just start throwing intake gaskets at it like a SBC.

 

[Trav]

Originally Posted By: Silverado12
From my experience, if the IAC is giving you problems, you're better off replacing it than cleaning.


This one is easy to test the electrical function on but they get dirty in the passages. You just don't go swapping this out without thorough testing and cleaning first its north of $250 OE.

 

[SHOZ]

Try tapping on the IAC when it's struggling with a screwdriver handle. It usually will open up and the idle will smooth out. Might as well try taking it off and cleaning it. Not much work.

 

[xfactor9]

In Park, does your engine RPM drop when the A/C comes on? If so, gently press the gas to raise the idle speed. Does the idle smooth out? If so, then your idle-air control valve is the problem. It is supposed to maintain idle RPM when the A/C comes on