Corollas2019-23ToyotasTech

Search Corolland!

By ouroboros, June 9, 2007



Hi,

I recently got my A/C serviced in anticipation of driving in TX this July. After the service we noticed that when the high idle circuit kicks in with the A/C compressor there is a high pitch whistling that rapidly accompanies it. The whistling disappears when the compressor switches off but the source of this sound seems to be the cylinder head.

I have not gotten a MIL status light yet and my understanding is that modern sensors will detect a vacuum leak very accurately so I'm thinking its not any vacuum lines. A/C works fine as well, no rapid cycling of the compressor clutch to suggest a problem with the expansion valve.

I've read elsewhere that the 1ZZ FE makes alot of strange noises. Could this be a noise that's inherent in the engine design? Could the high idle be activating the VVT solenoid (for pollution control) and what I'm hearing is oil moving through the actuator?

Thanks for your thoughts.

Hmm - I've never noticed a high pitched sound that might be attributed to the VVT-i mechanism. You are correct that the 1ZZ-FE is one noisy engine - lots of buzzing, clanging, ticking, etc going on under there - timing chain being a big culprit of the noise. If you can pickup the sound of oil moving through the valvetrain - then your hearing is a heck of a lot better than mine.

I did have some high pitched squealing noise (electrical sound) early one with my car. That was fixed with the addition of an aftermarket grounding kit. Can't say that it added anything to fuel economy or power - but my lights are a whole lot brighter at night and don't dim when I have a heavier electrical load. At first I thought it was a bad alternator or voltage regulator - but it turned out to be some ground loop noise that was taken care of with the better grounding wires.

Hi,

I recently got my A/C serviced in anticipation of driving in TX this July. After the service we noticed that when the high idle circuit kicks in with the A/C compressor there is a high pitch whistling that rapidly accompanies it. The whistling disappears when the compressor switches off but the source of this sound seems to be the cylinder head.

I have not gotten a MIL status light yet and my understanding is that modern sensors will detect a vacuum leak very accurately so I'm thinking its not any vacuum lines. A/C works fine as well, no rapid cycling of the compressor clutch to suggest a problem with the expansion valve.

I've read elsewhere that the 1ZZ FE makes alot of strange noises. Could this be a noise that's inherent in the engine design? Could the high idle be activating the VVT solenoid (for pollution control) and what I'm hearing is oil moving through the actuator?

Thanks for your thoughts.

I was just listening to my 1ZZFE and I hear the same sound. I don't think it has anything to do with A/C though, I had it turned off. It happens when it's idling and I manually open the throttle a little bit (just like it does when the compressor kicks in). I assume it is normal, and I guess it could be the VVT mechanism, there are some tight passages in there and oil is flowing pretty fast... I don't think it's anything out of the ordinary, I remember hearing same sound when it was new.

It's definately true that the 1ZZ-FE engine makes alot of strange noises. About the best example is when I'm cruising at about 50 mph on route 9 (a heavily used local state highway around here). I guess because the 1ZZ is optimized for fuel economy, it likes to lock itself into low rpms. At that speed, the engine generally establishes itself at about 1800 rpm. When I come to a hill, I step on the pedal a little bit more to get more power and keep my speed, but the engine's rpm/power doesn't go up. Instead, I get this shuttering sound throughout the car. The solution is always to step on the pedal even more until I see the tachometer jump 500 rpms to about 2300. The shuttering goes away immediately.



Topic List