Loss of uphill power with engine noise

[94PgherConti]

1994 Conti Exec with only 107K miles.

NOTE: The check engine light is NOT on !!

Not sure how to expalin this noise, but going uphill (or even level with very hard acceleration) the engine emits a sound like a quickly deflating balloon.
Not sure what "valve chatter" is or pinging really sounds like, but deflating ballon (when left go into air) is best analogy I can think of. Another is the sound when holding your tongue loosely against top-inside of roof of mouth behind front teeth and humming and forcing air to vibrate tongue ???.

Also, both my wife and I verify a NOTICEABLE loss of power going rather steep and short uphill in our residential area (not high speed).

Am I screwed?

 

[Glorywagon]

1994 Conti Exec with only 107K miles.

NOTE: The check engine light is NOT on !!

Not sure how to expalin this noise, but going uphill (or even level with very hard acceleration) the engine emits a sound like a quickly deflating balloon.
Not sure what "valve chatter" is or pinging really sounds like, but deflating ballon (when left go into air) is best analogy I can think of. Another is the sound when holding your tongue loosely against top-inside of roof of mouth behind front teeth and humming and forcing air to vibrate tongue ???.

Also, both my wife and I verify a NOTICEABLE loss of power going rather steep and short uphill in our residential area (not high speed).

Am I screwed?

Check the exhaust. Sounds like it might be plugged up. Maybe a bad cadilac coverter ( not sure of spelling Sorry) I had it happen on my 89 TC the Cats. come apart and plugged up my muffler. About drove me crazy till I found it. Had to replace the Cats. and the muffler at 110,000 miles.Sounded like someone stuck a banana up my tail pipe and power lose on hills. Took it in for a tune up didn't help. changed fuel filter didn't help. i had no check engine lights on. So I unbolted the Cat's and took it for a drive Wow ran good. So I replaced the Cats. and sill had the same problem . So then I cut the muffler off and it run fine. So I replaced the muffler. Zoooom.

 

[MichiganTeddyBear]

might be bad cats as mentioned.. or a collapsed pipe in the exhaust.

on pre-96 vehicles, this usually does NOT throw a code, as they dont have downstream o2 sensors, only 96-up (obd-II).

try disconnecting the flex pipe from the exhaust/cat pipe and seeing if there are any cat parts floating around. even take it for a drive, that will let ya know if the muffler, or something downstream from the cats is plugged.

 

[94PgherConti]

?? - The cat / muffler issue would cause the engine noise as well?

 

[Frat-man-du]

Yes, the engine is having to force exhaust out and the hissing is symptomatic of a plugged exhaust.