02 Impala Acceleration Degrading

[luvmy02impala]

Hello, this is my 1st time post....

I really enjoy driving my 02 Impala, in the last year I had a $900 intake manifold replaced, new rotors and pads, with new tires. I have also replaced the fuel filter and serpentine belt, as well.

The acceleration is degrading. When I push the gas pedal, I really have to mash it to get the car to accelerate. The gas mileage is getting worse, gone from 300/400 a tank to 200/300 a tank. It seems not as responsive as wehn I bought it used a year ago-used (no warranties on it) and the car has 83k miles on it.

There are no idiot lights on the dash board that light up. I also have a 2003 Impala that accelerates just fine.

Any thoughts or suggestions?

Thanks, Tom

[simonswu]

My '01 base has got similar problems, loss of acceleration power, and worse gas mileage. When accelerating, a kind of air sucking noise can be heard. Many say it must be from catalytic converter. But my dealer insists it's normal, and they say the cat converter is fine based on their test, and some of new impala's even make the same noise....Anyway they could not find anything wrong.

I'm going to take the car to another chev dealer, hopefully a better one.

[bigrod118]

well you say it has 83K on it. and in the manual it says to check/replace spark plugs and wires at 100K I personally dont think that plugs and wires are going to last that long, and since your almost getting there, that might be something to look at.

[luvmy02impala]

Thanks, I called one dealer and they said it could be the cat, but wasn't sure unless they had the car to inspect. He said the cat probably is ready to go with that mileage, since it is a fairly new car with high mileage.

I know it doesn't drive right, I have an 03 Impala (same model) and it accelerates pretty dam quick...

-Tom

[luvmy02impala]

Originally Posted by simonswu

I'm going to take the car to another chev dealer, hopefully a better one.

Let me know what the dealer says, it would interesting to see if the same issue. I just hear any sucking noise. With the window open when I hit the gas pedal, you have hear the motor respond (almost kind f muffled, like it is restricted/muffled), the car just doesn't want to accelerate.

The car had accelerated fine up to about 2/3 weeks ago. The car sat for a moth while I was out of the country, I wonder if that had something to do with it.

-Tom

[Impala05Man]

What engine does the 2002 Impala have in it. I have a 2005 Impala LS with the 3.8 liter and I don't hear any noises like that with mine. If its the 3.4 liter you have GM has had numerous problems with that engine.

[bermis519]

Well here is my edumacated guess.

I am experienceing the same problems with the lack of acceleration. When i give it gas, i can hear a hissing sound like the exhaust is backed up. The reason your car is getting crappy gas milage is because you have to push the pedal down more to maintain speed, when you press the pedal down more you are feeding more gas to the motor. Your problem is the converter. I have replaced spark plugs, wires, new fuel filter, had the fuel rail and the injectors clean and everything passed just fine. I'm also experiencing a rough idle too. I'm 99.9 percent sure it's the converter because it's the only thing that would hiss underneath the car from back pressure. If it was anything else in the exhaust as far as a hole it would simply be loud. Your best bet is to break down and get a new converter. I have decided to go with an aftermarket converter with a simulator so the check engine light doesn't come on. Why spend 500-600 bucks on the same converter you know is going to fail, or put a cheaper high performance converter on it with a simulator. I tried to trade mine in at the dealership when they had the employee discount thing going on and they would only give me 2500 bucks for a 2000 base impala, cd player, a/c and all that. The car is in excellent condition, well to them because i never told them what hell i have been thorough and i believe they should get their problem right back and I don't feel one bit of remorse doing so. But to give me 2500 bucks for a car i paid almost 15000 dollars for four years ago really pisses me off!

But i see am just rambling on again. Just thought i would give you guys my opinion and educated guess.

Mike

[MCO_Death]

Originally Posted by luvmy02impala

Hello, this is my 1st time post....

I really enjoy driving my 02 Impala, in the last year I had a $900 intake manifold replaced, new rotors and pads, with new tires. I have also replaced the fuel filter and serpentine belt, as well.

The acceleration is degrading. When I push the gas pedal, I really have to mash it to get the car to accelerate. The gas mileage is getting worse, gone from 300/400 a tank to 200/300 a tank. It seems not as responsive as wehn I bought it used a year ago-used (no warranties on it) and the car has 83k miles on it.

There are no idiot lights on the dash board that light up. I also have a 2003 Impala that accelerates just fine.

Any thoughts or suggestions?

Thanks, Tom

My 2003 is having this exact problem also, have yet to get it into the shop. I'm assuming the Cat's or something with the transmission. It won't accelerate for piss getting on the highway or up to 55 for that matter and the gas milage went to crap.

[luvmy02impala]

Originally Posted by bermis519

put a cheaper high performance converter on it with a simulator.

I have the 3.4L engine. Where can I get this cat & simulator. I haven't heard of this previously. Will the higher perf cat last longer?

I have 83k on the car. When it drove well, it drove really nice.

-Tom

[victimizati0n]

Originally Posted by luvmy02impala

I have the 3.4L engine. Where can I get this cat & simulator. I haven't heard of this previously. Will the higher perf cat last longer?

I have 83k on the car. When it drove well, it drove really nice.

-Tom

Just go out and get a cat (like from napa, or advance auto parts) that is a direct fit for your car.

It will mostlikely be a better one, and it will probably last the rest of the lifetime of your car.

Im assuming he told you to get a simulator, because the cars computer will think something is wrong, and your check engine light will come on.

[maxwedge]

Why replace the cat, have it scannned and look for maf readings, o2 readings, and fuel trims these things will tell what is going on, if all checks good, have the cat checked for excess back pressure. Very unusual to replace cats at these mileages. without something causing them to fail.

[MCO_Death]

Originally Posted by maxwedge

Why replace the cat, have it scannned and look for maf readings, o2 readings, and fuel trims these things will tell what is going on, if all checks good, have the cat checked for excess back pressure. Very unusual to replace cats at these mileages. without something causing them to fail.

Very unusual is the definition to a lot of problems that have been posted on these boards

Had a 91 Lumina litrally blow off the cat converter at 48k miles from buildup in the cat and large enough backpressure. That was a fun sound...

[supervisor1886]

Plugged or cracked cat
1 Rotten egg smell (running lean)
2 Too hot under there
3 No power
4 wont rev higher that 3000 3500 RPM
5 Sounds like its plugged (no hissing)
6 Oil becomes very dirty too soon
7 bad gas mlg

I would run the car without the cat if there s only one O2 sensor.


Solutions : aftermarket hi flow cat with the A.I.R. setup $100 + high perfomance muffler. For more perfomance solutions (which are cheaper than using OEM stuff) refer to CAMARO forums.


Also what you missed here is
1 Ignition system and the coils (wires)!
2 Bad o2 sensors or Taiwan one
3 Vacuum leak anywhere
4 Bad fuel pressure regulator or pump (filter)
5 Any other sensor causing to run lean or very rich (sometimes there wont be codes set)
6 Hydrolic lifters need adjustment

[maxwedge]

Supervisor , no adjustments on the hydraulics. MCO, cats fail mainly due to engine driveability issues such as a long standing misfires or as Supervisor said any condition that causes to rich or lean a mixture that over time is not corrected. I have had 5 GM fwd cars that have all gone 200k, 3.1, 2.8 and 3.8 engines.no cat failures. Of course issues posted in this forum are dealing with problem cars that tend to generate a record of cat failures.

[luvmy02impala]

Originally Posted by MCO_Death

Very unusual is the definition to a lot of problems that have been posted on these boards

Had a 91 Lumina litrally blow off the cat converter at 48k miles from buildup in the cat and large enough backpressure. That was a fun sound...

My previous car was a 88 Olds Delta 88, when it had 160k the cat let go, it blew pieces of internal cat goodness out the back. Had to replace the muffler (since Meineke said they were unsure how much debris was collected there - I am sure this was a $$$ gimmick).

There was no degraded acceleration, no bad gas mileage, it just went and car shut off, I thought I blew the engine. That car now has 190k on the 3800 and my mother in law bought it with a bad tranny. That car had balls, it was as good as it was when I bought it with 80k miles on it.

-Tom