markdiy

Poor acceleration '02 Impala

Acceleration on my 2002 Impala (72k miles) is getting worse and worse. I first noticed it when accelerating up hills on the highway. Now, it's getting worse, even when trying to accelerate up a hill from a stoplight -- at 15 to 20 mph. This morning, I replaced the fuel filter. That seems to help a little at the higher speeds, but hasn't appeared to do much at lower speeds. What would be some causes for these symptoms? The transmission feels and sounds fine. I guess it could be the fuel system or the air flow system (MAF or filter). Any thoughts on what could be causing it? How would I know if the fuel pump is going bad?

davo

Check the fuel pressure with a guage and also the catalytic converter for a restriction.You have checked the air filter,correct?A dirty maf sensor could cause the problem also.

markdiy

Thanks for the reply. Hopefully it's nothing major. I don't know much about Chevys. I have a few questions.

1. I have not checked the air filter, but will do so. Will a dirty air filter hinder performance that badly?
2. I rapped on the cat, but didn't hear anything rolling around (just had one go bad last month on muy Jetta). How can I check if it's plugged?
3. I suspect the MAF is right next to the air filter. Is cleaning something I can do myself?
4. I can go to Autozone and they can read the ODBII. My check engine light is not on, but maybe there may be a trouble code in the computer.

davo

#1 yes it can #2hitting a convertor doesn't alwaysn yield an answer it needs to be removed or tested on the car at an exhaust shop.#3 if your car has a 3.4 it is right next to the air filter housing,if a 3.8 it's in the throttle body itself.Yes you can clean it yourself with carb cleaner or better yet brake clean.#4 By all means have the codes checked but do it before you have touched anything else or the results may be self induced.

markdiy

Thanks for the response. Ended up taking it to my mechanic who said the codes are consistent with a plugged cat. What causes the restriction?

Also, I've got less mileage than the 80k Federal warranty. Will the restricted cat need to be replaced and typically fall under this warranty? I have to take it to the dealer service dept. for the repair and I typically get the runaround there...

davo

If the cat has failed under the 8yr 80k warranty it should be at no charge.What are the code #s.This is very important for a warranty claim.Do you have a remote start installed on the car?

markdiy

The codes were p0404 and p0327. They also said they found the exhaust restricted.

davo

p0327 is a knock sensor code if it is faulty it could cause the lack of power you have.Disconnect the knock sensor and see if the power returns.If you go to a dealer to have the cat checked and it's something else causing the problem not under warranty you will pay.

lp_spark

Posted By: markdiy Thanks for the response. Ended up taking it to my mechanic who said the codes are consistent with a plugged cat. What causes the restriction?

Also, I've got less mileage than the 80k Federal warranty. Will the restricted cat need to be replaced and typically fall under this warranty? I have to take it to the dealer service dept. for the repair and I typically get the runaround there...

You probably fixed this by now, but just for info if others are searching for an answer.

I brought my 2001 chevy Monte Carlo SS into the dealership today and just picked it up. The syptoms were identical to yours. It turned out to be a plugged cat converter. The mechanic said that although it's rarer in the monte carlos, it's extremely common in Impalas and they see a lot of them come in. Most of the time the cars can't even accelerate over 30 mph.

The repair fell completely under the emissions warranty and I didn't have to pay a dime. They replaced it out completely. I also only have 30,000 miles on my car.