Hey guys, I've been a lurker here for a good amount of years. I drive a 94 Z28.

Today as I was driving, after I went WOT at a certain point in the 4000rpm range I began to notice a loss of power. After that, it seemed to get progressively worse. Every time I step on the throttle a bit harder the throttle response basically feels like a cracked straw sucking in air... or perhaps a big straw sucking in only a narrow amount of air. It sounded like it too, like a big whiff of air. Maybe someone snuck a turbo under there when I wasn't looking =/

Anyway, I noticed it getting progressively worse so I pulled over to let it cool down. Upon starting up the car again, there was loud screeching noise coming from what it sounds like the engine block and not the fan belt. I shut off the car and let it cool all the way down.

When I finally restarted the car, right at startup it made a quick screeching noise, and then went back to normal idle. But after revving the engine past 2500rpm, the screeching noise would come back. I drove home under 2000rpm the entire way, and everytime the rpms would climb I would feel the loss in power.

Can anyone venture a guess or know exactly what the problem the symptoms on my car describes? Thanks a lot for your help, I appreciate it.

 

You have AC? Possibly the compressor seized up, or the bearing it idles on is toast.

 

might be a vacuum leak... or the ac compressor, both weould give you those symptoms. any surging?

 

Catalytic converter is my vote. Pull the belt. If it continues to do it... you have found your culprit.

 

Thanks guys for the quick replies. There doesn't seem to be any surging. Now that you mentioned it though, my AC has stopped blowing cold air recently. Could this together point the problem to possibly the AC compressor? Also, I'll check for any vacuum leaks, the cat, and the fan belt as well.

Is there any chance that the problem is more serious like something in the engine?

Once again thanks for the help.

Edit: Also, would a bad AC compressor be the cause of the lack of power?

 

No.The next time this happens,pop the hood , while the engine is running,and watch for which pulley is freezing up.Could be the belt tensioner,but more likely the air, or power steering pump pulley.Hope this helps.

 

Sorry,just a thought,how many miles on the cat?If over 70000 original,might be that.G.M. says the cats for those years were not up to par.My02.

 

Thanks for the quick replies, I'll definitely have the pulley and cat checked out too. The car is at 138k right now and I don't think the cat has ever been changed. How would that cause the loud screeching noise though?

Also another thing I just remembered. The first time I started the car back up, when it was screaming... the idle was at around 1300-1500 rather than the normal ~600rpm area.

Thanks again.

 

A video would be great. Knowing exactly where the sound is coming from is important. If its inside the motor that would be bad.

 

My friend had that problem, but that was because he fried his Alternator.
If you have a system hooked up that can happen.
Loss of power could mean alternator.
And i have no clue on screeching.

 

Catalytic converters get clogged and it has to release the pressure somehow. I thought my friends 93 Z was about to burst. The sound coming from the exhaust relieving pressure was strange to say the least.

If it is a shriek like when your tires squeal from hitting the brakes too hard I'd be looking at the serpentine belt.

 

belt will make the high pitched squealing, which could suggest that it might be a problem with one of the pulleys getting stuck or something to that sort.. also, my alternator has been making a whining noise for the past 6 months or so, i'm assuming it's on its way out... never had a loud screech before, just sorta whistling from the alternator. i've had an air leak at the intake elbow before, and it made sort of a whistling sound. i don't know.. just check all the usual places for the vacuum leak, the pulleys for seizure and what not. if the cat is blown, it won't make that sound. whenever you step on the gas, it'll make a sound like pebbles being tossed in a tin can, and you'll notice your car will run warmer and it'll feel like it's running like ****... doesn't sound like your cat is blown to me though

 

Thanks guys for the help. I'll make sure to look into everything. Anymore ideas would be definitely welcomed. I'm just hoping someone would eventually say "Oh, I had the exact same problem, here is what was wrong with it..." haha, one can hope right?

 

Well I have this exact same issue... It just started yesterday morning tho, and I have no idea what it could be, honestly it sounds like a spun rod bearing or maybe a cam bearing possibly.

Basically I have all the same symptoms described above, it sounds like I'm going through a tunnel at WOT or like I have a supercharger sorta but there an alarming loss of power, my exhaust is quieter then before and my intake is noticeably louder like to the point where I wont to drive my only car. And the whining sound starts at WOT around 3500ish and gets louder the higher it revs.

I really really really hope this isn't something major and/or internal because I literally don't have any money to fix anything right now =(

Any ideas? I'll see about posting a video if I can.

Oh and I have a 1LE AC delete pulley, no compressor.. And 185,xxx miles on the original motor..

 

Next time you take the car out and the problem arises check 2 things; 1) watch the volt meter to see if it fluctuates and 2) see if the steering gets "tighter." If 1 is your problem then your altenator is probably seizing up, if it's 2 then more likely the power steering pump. If neither of these happen it doesn't eliminate them as being the culprit but a look at the A/C compressor would be next on the list.

FWIW I had a similar problem a while back. Every once in a while the car would act real sluggish and "squeal" upon startup. I replaced the belt thinking that the OE cracked and dryrotting one was to blame. About a week later I had a day full of errands to run so the car was in constant use. Went to fire the car up and after a little bit of a hard start (nothing excessive) smoke started pouring out of the hood. Quickly shut it off and popped the hood to watch my new belt melt and "snap" right off the altenator pulley. Keep an eye on your symptoms so it doesn't leave you stranded somewhere.