[fmw63]

Went to look at a 92 Deville for sale today. It was a nice car, but made a strange noise.
While sitting there in park, after revving the engine up to maybe 2k, after releasing the
pedal, after about 3 or 4 seconds, there was a snap sound. Not a pop, like a backfire, not
as big as a clunk. I was thinking maybe the isc motor, but the sound was "larger" than that.
Any ideas what that could be?

 

[fmw63]

Nothing?

 

[dchavezo]

Could have been anything honestly. Was the sound reproducible? Does it happen every time? Or how many times out of 5 or 10?

Does it happen when you do anything else?

"A snap sound" is pretty general. If you could be more specific or post a recording that might help.

 

[fmw63]

Yes, it seemed to happen every time. Didn't hear the noise
any other time (like driving). The guy at the place said they
had replaced a mount, but this noise wasn't immediately during or
after decelerating, but 3 or 4 seconds after. The car is about an hour away - can't get to it to try again.

 

[dchavezo]

Yes, it seemed to happen every time. Didn't hear the noise any other time (like driving). The guy at the place said they had replaced a mount, but this noise wasn't immediately during or after decelerating, but 3 or 4 seconds after. The car is about an hour away - can't get to it to try again.

Could be the throttle cable getting caught then released on something.

----------

Could be a noisy isc. If it were me I'd put the car in park pop the hood and rev from the tb to replicate it with my head in the engine bay. Then maybe it'll become more apparent or obvious what it is