97 Camry...low idle on damp mornings....

Bad plug wires, loose - bad distributor cap are the first places to look.

If his engine is not running on all its cylinders, I agree with your idea, but he didn't say it was running roughly which would be the case in that event. A healthy (normal compression) cylinder which has no spark, becomes an unbalanced load on the remaining good cylinders causing marked vibration.

Sounds more like the throttle butterfly valve is sticking or the idle air control valve (IAC). The IAC can be cleaned with a soft toothbrush and carby ceaner. Some folks recommend doing this with the assembly off the car to prevent damage to the O2 sensor.

Jason

He did say when damp, How would dampness affect the throttle body . IAC I could see with bad electrical contacts [ it does have power doesnt it]

Condensed moisture inside the TB making the normal gunk all that more sticky/glue-like?

Jason

Thanks for all the information. Did some net research on cleaning the IAC valve.. Saw this posting with a diagram on how to spray carb cleaner into an opening just inside the metal housing after removing the big black air hose. It sounds a bit too easy to resolve the problem and they don't mention a toothbrush. Maybe it's time to return to Firestone so they can relieve me of more of my money. When I had it there six months ago, they did everything. Fuel filter, fuel injection cleaning, plugs. Not sure if they looked at anything in and around the throttling section of the engine.

When I was looking at my engine. I looked for a round protruding carousel that I thought would be my distributor cap and didn't see anything like it. What am I looking for there?

Thanks

an

hose.

Time and again the IAC has been mentioned. This engine has the crankcase-PVC valve breather hose admitting fumes into the inlet (for burning with the normal mixture) just up-stream of the IAC,....hence the problem, especially on older cars.

Maybe it's time to return to Firestone so they can relieve me of

everything.

carousel

it.

Do you have the 4 cylinder? If so, its on the righthand end of the engine ( as observed facing the front of car),...as for the V6,..I dont know,..anybody able to answer him?

Jason

Toothbrush is for cleaning the throttle body with the engine off. That would be if the throttle is sticking coming off idle because the butterfly valve is mired in deposits. IAC (idle air control valve) is for the four cylinder. Small square hole at the bottom of the throttle body right in front, just right of center after "removing the big black air hose." That little square opening lets air flow past the closed butterfly valve. The butterfly valve moves when you press on the gas pedal, so at idle it would be closed. Air entering that small hole is then metered by the idle air control valve under the throttle body. There's a small pintel valve that is electronically regulated to control idle speed, and that little valve can get clogged such that the computer signals to the idle air control valve aren't properly executed. Spraying an emissions control safe carburetor cleaner into that small opening with the engine idleing should clear it up, or you could remove the throttle body for a more complete bench cleaning.

IAC does control idle speed, but problems are ususally related to temperature not dampness. Example, stumbling low idle only when cold. Dampness more likely points to an electrical problem - guessing the igniter or coil. Not exactly the same, but my Toyota truck would never start in the rain until the igniter was replaced. Lots of fun, covering the hood with plastic and getting soaked trouble shooting non start only in the rain - ran fine otheriwise. If you have the non California version Camry, with the ignition coil in the distributor, these can also be a source of problems.

If you're not doing the work yourself, why the aversion to genuine Toyota service? At least that way you know you're getting factory spark plugs, etc., instead of potentially an aftermarket brand, and the techs have the specialized tools, diagnostic equipment and experience born of working exclusively with Toyota all day long.