I am stumped at the rpm I'm having with my 2005 Camry SE V6 (bought new with ~28,600 miles currently on the odometer).

Since the car is over 10 years old, wasn't going to take a chance on the timing belt so I had it changed back in the summer at a local shop with original timing belt and water pump by Aisin. Prior to the change, my car always had a low rpm (below 500) on cold start which was not an issue at all since it ran great. Stepping on the gas from a full stop, the rpm was always below 1,000 rpm and I wouldn't normally hear the revving sound. Now, after the replacement, the rpm goes to 2,000 then drops to around 1000 from a cold start within 5 minutes and stepping on the gas from a full stop can reach close to 1,500 rpm then drops after 2nd gear kicks in and I would hear the revving sound.

During the replacement, the mechanic broke one of the tension bolt / screw and had to drill it out. He compensated by putting on another bolt and nut or something to connect the tensioner in place. Would this be the cause of the high rpm? Or maybe he tightened all the bolts too tight (he didn't use a torque wrench to tighten)?

After a couple of months, I cleaned the throttle body and resetted the idle. After the reset, the rpm seems to have improved as it dropped from 2,000 to 800 with 3 minutes at cold start. But in my experience, this is still too high and the rpm from a full stop and go remains the same.

Any suggestions appreciated.

 

Mechanic could have failed to reconnect a vacuum hose or wiring plug to a sensor. Check the passengers side of engine for any loose vacuum hoses or harness plugs.

Does the engine otherwise run OK. Same power and MPG?

There is no mechanical idle speed control on the car. The computer sets the idle speed via the IAC valve. The IAC valve physically controls idle by adjusting the amount of bypass air around the throttle plate.

If this issue had come up without the belt change being done, would suggest to clean the IAC valve.

 

The mechanic replaced the timing belt and water pump from below the car while on the lift. The only thing he removed from the top was I think the engine mount (really not sure)? It was that metal bracket where you wound connect the black jumper cable to for grounding. I don't think he disconnected any vacuum hose or wiring plug to a sensor. If this was the case, wouldn't the check engine light be on?

The engine seems fine and runs OK with same power. MPG wise...not sure. Just the rpm to be high and revving sound noticeable from 1st to 2nd gear...

 

If the idle issue started right after the belt change, then perhaps something happened as a result of the work done.

A disconnected or damaged vacuum hose may or may not set a trouble code. It depends on what harness plug was removed to set a trouble code. The trouble code system does not monitor everything.

Is the throttle plate stop sitting on the adjustment screw? This screw is there to adjust the throttle stop location in the throttle bore and not idle speed. Idle speed is set via computer using the IAC valve.

Check if the throttle body has an anti stick throttle device to prevent throttle sticking at engine start. Basically a vacuum powered dashpot (can) with a pin in the center that lifts the throttle stop higher when the engine is off. When the engine starts, vacuum draws the pin down to the throttle stop screw.

Check throttle cable operation. As recall it doesn't run directly from the pedal to throttle body but goes to the cruise control box.

Suppose it's possible the mechanic failed to time the crank/cam pulleys to each other properly. It's possible the engine would run but it should have others issues.

If you think everything was installed OK then read up on the internet for cleaning the IAC valve. If dong so use only a throttle body cleaner stated to be safe for plastics as the valve is plastic.

Is the idle RPM still high. Then showing up when shifting between 1st and 2nd?

 

Happy New Year Joey P.

Realized I omitted that I had the power steering belt changed as well on the same day I had the timing belt and water pump replaced. Would the replacement of the power steering belt cause the high rpm? I've also checked whether there are any loose vacuum hoses or harness plugs on the passenger side and found none at the moment....

Thanks again.

 

To confirm prior statements, does the engine run the same as before the timing belt was changed? Same power, same ability to rev engine quickly, same MPG? If the timing belt was installed incorrectly it would show up in these items.

Replacing any of the other belts such as power steering would not cause issues.

Check the IAC valve which controls idle speed.

An idle speed of 500 rpm is too low. Should have been around 750. The RPM should be higher when engine cold then come down to something around 750.

What happens when the AC is on? The idle should pickup when he AC compressor runs to compensate for the compressors load on the engine.