Why does my Impala have loss of power?

Question

My 2004 Chevy Impala has a trouble accelerating. It also dies if I try to accelerate too much (like trying to get it up pass 40 MPH. 3 scan tests from 3 different scan tools show no codes found for anything. In the pass week, I have replaced the fuel filter, crank shaft sensor, throttle body sensor, and it needed a new battery. The car lets off a rotten egg smell but the dealer says they tested the catalytic converter and it is fIne. Why does my car die? Always have loss of power and why does it smell like rotten eggs? PS. Every time the car dies, it starts up immediately without having to wait for anything to cool off.

Answer 1

was it sitting there for a while?

and doing nothin?

it could be your freeze plugs,

or it could be your oxygen sensor

Answer 2

try this---pull the wires off the o2 sensors and drive the car. If it runs better at all its the cat converter

that rotten egg smell is asign of a fucked up cat converter. and while your at it get a new muffler.

back pressure from the rear end will slow everything down.

Answer 3

Not sure and nether are the other two. your getting too much fuel for some reason, that smell is the cats doing their job

Answer 4

There is two issues here.

#1 the easy one.  the rotten egg smell is the sulfur in the gasoline you're using.  It will collect in the cat converter until it gets hot (hard accel or prolonged idle) then it will release (smell).  Not a fault, but normal outcome to poorly refined fuel.

#2, loss of power.  Sounds like a fuel issue.  You need to put a fuel pressure gauge on the vehicle and watch during the malfunction.  If you already put a filter on it, the outcome will probably be a pump.

Good Luck

Answer 5

Sounds like a restricted exhaust system although you could have a vacuum leak at the fuel pressure regulator.

Answer 6

Sounds like you might have a bad mass air flow sensor. While the engine is running reach over and unplug it and see if it doesn't run better. If it does you might try cleaning the inside of it or replace it. I cleaned the little wires inside mine with a small paint brush and spray choke cleaner. Mine had dust and dirt on the little wires inside and once cleaned engine ran fine.