Pop Pop Pop

[TopherS]

For the past month or so, my car has been making this odd "pop pop pop" noise from under the hood; sounds like it's somewhere around the left front wheel area.

It seems to be in the morning when I first am off to work, it does it once and then doesn't seem to do it again. IIRC, it has, on occasion, done it after work, when I am going home, too. At first, I thought it might be something in the suspension, as it happened to occur while driving, but yesterday, it happened while I was sitting at a stop sign near my house, waiting for traffic to clear.

The sound is very regular, takes about a second for the three pops to sound and the three pops are evenly spaced. The pops aren't very loud...I suspect that I hear it only because I usually drive with the radio volume pretty low, if not off. I would guess that at more normal volume, one would probably not even notice the sounds. Also, they don't have much of a metallic sound, either. I haven't driven with the windows open, as it is still very cool in the mornings, but the noise comes in well enough through the firewall and I would guess that you can hear it from the outside.

My extended warranty expired in April, so I had the entire car gone through twice (once by my mechanic and once at the dealer) prior to expiration. Everything appears to be in working order (although both missed a wet water pump , which I ended up replacing out of warranty; and both missed a burned out brake light...so it's possible they missed something else while they were at it). We are taking this car on a 3-4K mile trip toward the end of the month, so if there's something that needs attention now, I'd need to address it very soon.

Any ideas as to what this sound is??? Thanks for your help.

[HotZ28]

Could this be the fuel canister purge solenoid, going through its regular purge cycle? Have you ever noticed this noise before? Do you have the AC control on auto, when this sound occurs? Is your PA supercharged? Sounds from under the hood transfer in mysterious ways! It can be hard to determine where, or what side it is coming from, while sitting inside the car!

[TopherS]

Originally Posted by HotZ28

Could this be the fuel canister purge solenoid, going through its regular purge cycle? Have you ever noticed this noise before? Do you have the AC control on auto, when this sound occurs? Is your PA supercharged? Sounds from under the hood transfer in mysterious ways! It can be hard to determine where, or what side it is coming from, while sitting inside the car!

I hadn't noticed the noise before, but it is very possible that it had been there all along, just I never noticed. I do have the AC on Auto at all times, so it was each time the sound occurred. My PA is normally aspirated, so no supercharger . I agree that it could be hard to determine exactly where it is coming from...the left front area is where it sounds like it's coming from (from where I'm sitting).

I don't know anything about the fuel canister purge solenoid (in fact, I've never even heard of it...goes to show how much I know ) At the risk of sounding like a complete idiot...what is it?

[HotZ28]

Click Here for more info on the fuel canister and how it functions. This is not model specific, however, the same info would apply to your car.

Let’s forget about the AC compressor clutch cycle. Your car has a variable displacement compressor known as the V5 and the compressor does not cycle on/off. This particular type of compressor, varies the stroke of the piston to control system pressure and demand.

Another thing you might check, would be the relays in the fuse/relay panel mounted on the firewall. You could have a relay with bad contact, causing it to flutter.

I almost forgot to mention the ABS module, as a potential canidate here.