Low, rough idle
 

Car was exposed to high water with hurricane Ike. No codes are present, idle is low, 500 rpms, and rough with ac on, almost normal with ac off.

RE: Low, rough idle
 

What year and engine type.

What is the idle RPM when engine off.

How high the water get in the car.

How is the engine idle RPM when you shift from Park to Drive or Reverse, does it also drop (if auto trans).

RE: Low, rough idle
 

What year and engine type. 2005 Base model 4 cyl

What is the idle RPM when engine off. Im gonna go with 0 , Alex. 800 ac off/ 500 ac on.

How high the water get in the car. 4"

How is the engine idle RPM when you shift from Park to Drive or Reverse, does it also drop (if auto trans). Barely, not enough to worry about stalling.

RE: Low, rough idle
 

my camry had starting/low idle problem only after a rainy day. I changed spark plugs and problem went away

RE: Low, rough idle
 

700-800 RPM idle when engine warm and in gear is OK.

The ECU may not be getting a signal that the AC has been turned on. When the AC compressor turns on the ECU will adjust the idle up to compensate for the load. The throttle is controlled by the ECU via a stepper motor.

If the problem started with the the flood, perhaps some of the wiring connectors that were underwater are still wet. Flooding of wiring can cause all kinds of strange problems.

Here is my video on:
How to Replace the Fuel Pump in a Camry