Chirping sound when starting and running

[swan00]

I have a 2000 996 C4 with an unusual problem: when crankiing the engine I get a chirp sound usually twice. When running if I goose the throttle I get the same chirp. So I removed the belt thinking it may be the alt., water pump, power steering. A/C comp or idler pulleys - no change in the chirping. Any ideas what might be causing this? Engine runs perfectly with no CELs. Also the clutch makes no difference.

[DBJoe996]

First, I would not run the engine without the belt. Would it be possible for you to have someone assist you so that you can listen in the engine compartment to see if you can isolate where the chirp is coming from? I'm leaning towards throttle body, air box or something along the intake system since it only happens on start up or goosing the throttle. Or maybe a motor mount...exhaust bracket...when ever the motor rocks. Might help to have someone goose the throttle while you listen in the engine compartment.

Edited October 22, 2012 by DBJoe996

[RFM]

Take a look if nothing is wrong with the fuel pressure regulator(s) on the fuel rails, sometimes vibrates the diaphragm(s)

[Richard Hamilton]

Dare I say a loose spark plug? Quite a common occurrence, and most people describe the noise as a chirp.

[spender]

Does it sound anything like this (video clip):

https://vimeo.com/51775214

I've got this problem right now.

[swan00]

Yes Spender it sounds exactly like that.

Also what is the problem with running the engine without the belt for 15 seconds???

[Richard Hamilton]

Just search this site for 'chirping'.

[phillipj]

Check your spark plugs. A loose Plug can cause a chirping sound...It's a common issue..

[swan00]

It was a loose spark plug. With the car on the lift it was clear that the chirp was on the left side of the engine. Number 2 was loose, but it only took about 1/4 turn to tighten it.

Thanks for the help.

[Loren]

It was a loose spark plug. With the car on the lift it was clear that the chirp was on the left side of the engine. Number 2 was loose, but it only took about 1/4 turn to tighten it.

Thanks for the help.

You need to give Richard a Reputation point - he nailed that one.