Could my 99 Camry timing be off?

Hello guys,

When I am accelerating either from a stop or while in motion, I am hearing a rattle/hissing sound from the engine through the open windows. The sound was much worse pulling the trailer last night or while going uphill. I'm thinking the timing is off or maybe something worse from the valves or throttle body.

If I leave the car in drive, place my foot on the brake and give the car a very quick, short burst of gas, you can clearly hear this rattle/hiss sound. I cannot hear the sound at idle or when the engine is at a steady, constant speed.

Any ideas what I'm hearing and where I might focus my attention?

Thank you.

Do you use 87 octane gas? If so, you might be hearing pinging of the engine. I sort of doubt it, but I can't think of anything else at the moment. Try a tank of 93 octane gas and see if it solves your problem. Could be due to a timing problem or a mixture problem, but I would expect that you would see your "Check Engine" light if that was the case.

Are your oil and coolant up to proper levels?

Timing belt OK?

Hi guys,

I am using the recommended gas as stated in the owners manual. All my fluid levels are up to their correct levels. I had the water pump changed during the winter and the belt was fine at that time so it wasn't changed by Toyota. They also cleaned out my trottle assembly at that time as well.

I'm beginning to get concerned that it's serious. Maybe a compression test will be necessary although my engine service light has never come on once since I've owned the car.

Thank you.

Timing rarely goes out of adjustment by itself.
The hiss could be a vacuum leak which could explain your problem.

Sure sounds like pinging to me.

A failing water pump also can make a fluttering sound similar. It will be noticable under different loads/rpm.
But you just had yours done. I agree with Brian R. Put 93 in an empty tank and try same driving conditions.
Will probably answer that.
Did the sound happen recently, or after the work was done?

Vacuum leaks get quieter at higher speeds. They are noisiest at idle.

Thank you for all your suggestions.

If I put 93 octane gas and the problem goes away, what servicing needs to be done so I can return to the lower grade of fuel? At todays gas prices, I don't want to use the more expensive fuel on a regular basis.

I must say however that it does sound like a vaccum hiss at times. However, to be that noisy, I think it would have to be a rather large hole or even a hose off. I have felt along a great many hoses in the engine and found no breaks.

Maybe Toyota could do a detailed analysis of the vaccum system during my next scheduled oil change which is due very soon.

Thank you.

If 93 octane solves the problem, you're ignition timing is probably too advanced. Either that or you're running lean. Both should give you a CEL. If your timing is off, should be a sensor problem.

Also might be your exhaust is plugged up - do you have a power loss?

Yes Brian, I have noticed a power loss especially when accelerating from a stop. That's also during the time when my engine makes the most noise. At that moment and when pulling the trailer or climbing up hill. Today while under the car I noticed that the flex pipe on the exhaust is really brownish in color from rust or heat. I wonder is this could be the source of my hiss/rattle sound although I don't see any obvious holes or breaks.

Thanks for your help.

Try the high-octane gas first. Then see if you get a normal exhaust note at 2000 rpm or so. Might show if there is a plugged-up exhaust. You might find a leak in the exhaust if it is blocked. That would be the noise you hear.