So, my girlfriend was driving back to school in her impala when we heard a grinding sound coming from the engine for about a split second.. sounded like when you hold the starter too long, and you hear the flywheel grind. After that, the car lost about half it's horsepower. No check engine light, no overheating.. nothing. The thing is like 10k miles overdue for an oil change, so I'm guessing that's probably a factor, but it runs smooth still in low RPMS, but when you give it 1/2 throttle or more, the RPMs dip, and come back up, and dip.. sort of like a seesaw. It runs eerily quiet now, but when you give it, again, half throttle or more, it's rather loud, and the rpms aren't constant. It almost sounds like there's some air leak when you give it a good amount of gas. Makes me think some vacuum tube popped off, but.. I'm not very experienced with diagnostics, or very familiar with this car.



To sum it up:

It doesn't smoke
It runs smooth at low RPMs
It shifts fine
It's not leaking anything
It starts and stops fine
The RPMs seesaw when you give it a lot of gas
There's a slight air-leak sound when you give it a lot of gas

if anyone has ANY idea, give me a shout, thanks

hmm
enough gas in the tank?

which engine is it?
how the air filter/ intake?

Sappy96 wrote:which engine is it?
how the air filter/ intake?

that for starters.

if you think it's a vaccuum leak, get a length of rubber hose, stick one end to your ear, and probe the engine compartment with the other end. run along all the lines ect. works pretty well.


Andy

it's not how fast you go, it's how you get there that counts.
ZZP XP cam, 1.6 rockers, 105# springs, speedbuilt FWI, 3.3" modular pulley, TOG headers,
3" exhaust, flomatched injectors
'97 GTP 14.06@100.6mph pre cam w/ 3.5" pulley, I/E