Snapping Sound (Engine Bay) 2003 3.8L

[Oblithian]

Hey so, I have a problem that I haven't been able to find the solution to for 2 years. I checked out similar topics but the answers didn't really make sense.

This engine has a sharp snapping sound intermittently while the engine is running, It almost sounds like high voltage electricity arcing, or the throttle body dropping (though were it theTB the engine would be surging). The sound does not vary substantially with a change in RPM, and it takes a few seconds of running to start. The rate of occurence is once every 2? seconds.

I would approximate the location to be top/rear passenger side.

I am going to try disconnecting the IAC and the TBS one at a time to see if one of those is somehow the cause.

Thoughts?

 

[BGreyWolf]

I don't think it's a spark plug wire, but if they're old (or the plugs are old) I'd start there; then maybe a leak in the EGR piping at the back of the exhaust manifold; and then on to more difficult things like flywheel/clutch/throwout bearing (if it's a manual) or flexplate (if it's an automatic); although those tend to be more connected to engine speed.

I'd pull the spark plugs and start by looking to see if there are any differences in how they look; if one looks fairly different than the others I'd pursue that route (fouling, bad wire, etc) first. If they all look nice and the wires look good, I'd examine the EGR pipe next.

Are there any codes/check engine light? The charcoal canister purge stuff is in the fender there and has a solenoid valve that could make that sort of noise; although I wouldn't think it would be loud enough to hear over the engine.

 

[Oblithian]

The charcoal canister has been giving me weird looks lately...
The plug wires are also suspect.

There is some other work I am going to do (see if that has any affect) then I will check back in.

Thanks!

 

[JRicky917]

wires are cheap enough, and you never know what could have worn with them having to make that turn around the back of the engine

 

[Cortex30]

Hey so, I have a problem that I haven't been able to find the solution to for 2 years. I checked out similar topics but the answers didn't really make sense.

This engine has a sharp snapping sound intermittently while the engine is running, It almost sounds like high voltage electricity arcing, or the throttle body dropping (though were it theTB the engine would be surging). The sound does not vary substantially with a change in RPM, and it takes a few seconds of running to start. The rate of occurence is once every 2? seconds.

I would approximate the location to be top/rear passenger side.

I am going to try disconnecting the IAC and the TBS one at a time to see if one of those is somehow the cause.

Thoughts?

How did you fix the issue?

 

[Oblithian]

So far I have only been able to acertain that the sound is most likely either the IAC, or sticking valves.

(I really need some kind of audio probe to identify the location, though it sounds like it comes from around the throttle body.)

I am going to try cranking it from time to time with the coil pack disconnected, to see if that has an effect (if it is the valves it should help).

 

[Sam36]

I'd just make a video with your phone and upload it to youtube or something and let us have a listen...

 

[Spdricer]

So far I have only been able to acertain that the sound is most likely either the IAC, or sticking valves.

(I really need some kind of audio probe to identify the location, though it sounds like it comes from around the throttle body.)

I am going to try cranking it from time to time with the coil pack disconnected, to see if that has an effect (if it is the valves it should help).

They sell a stethoscope (like a doctor uses) but instead of a round pad at the end (to listen through flesh) it has a metal stick and anything you touch it too will be dramatically pinpointed so u just move it around touching the engine in different areas while its running and you find where the noise is almost instantly.