Screeching and clicking sound

[Hybridtheorynz]

Hi guys,

First post on here. I've had a 2004 Toyota Allex for about 3 months now, and I've noticed this weird issue - only happens when its warm, ie been driven for about 30 mins or so.

Problem #1 - Slight screech when I touch the accelerator pedal. It's a VERY slight touch. At times it will make this sound during idle as well but momentarily. I've confirmed that the belt is tight, as there is less then 1/2 inch flexion.

Problem #2 - After work today, I thought I would try and narrow down the screech, so I opened the bonnet and had a go and isolating the sound. The sound is def coming from the right hand side of the engine bay - ie away from the serpentine belt. As soon as I opened the bonnet, I noticed this sensor that was clicking quiet loudly - Not sure if this is related, but I unplugged it and back in, and it went away - But it came back after a while. I've attached a pic of the sensor - Could someone please advise what this is?

Any help would be MUCH appreciated!!!

 

[Turborolla]

Hello,

That, my good man, is a vaccuum service valve (VSV) I don't remember the specifics, but basically, it is part of the emissions system. I'd have to double check but I am pretty sure that it vents the fumes from the charcoal canister to be burned in the intake. It only opens under certain vacuum pressures, hence why the screech happens when you touch the gas pedal and increase vacuum. The screech is probably a loose vacuum hose or a bad VSV. However, are you sure it is coming from that sensor, and not the airbox itself? The airbox could be amplifying a bad noise coming from the engine.

 

[Hybridtheorynz]

Hey buddy thanks heaps for the reply.

Yes, positive. I have put my finger on the top, taken the connector while the engines running, then put it back. When doing so, I can hear and feel it clicking.

What happens if that sensor is bad?

 

[Turborolla]

Your charcoal canister won't vent and you may throw an emissions code. I would replace it, you can get them from your local Toyota dealership or a junkyard.