Low Power problem??

I know this is not much info to go on but let me see if I can get any direction on this... I was attempting to pass another vehicle moving at around 30MPH... I pushed pretty hard on the accelerator (not to the floor) expecting a smooth acceleration... Instead there was a complete hesistation for a couple of seconds and then I couldn't tell if the front wheels started to spin or the traction control kicked in.. But the result was very poor and slow acceleration... Not anything near what a 200 HP motor should do (the AC was on)... I backed off and more slowly accelerated and then it seemed smooth... Could this be a low power issue due to a clogged catalytic converter??... Maybe a tranny problem?... Moderate acceleration seems OK, but I tend to drive with a light foot... Any ideas how I could narrow down if and what might be the problem??... Oh yeah, it's a 2001 Impala LS with the 3.8L motor... 50K miles on the car...

Anyone?

I seem to notice a loss in power from about 25mph to 45 mph... Like there's a big dip in the power (torque) curve... Acceleration from a stop in 1st gear seems ok...

Have you done any basic tune up items like spark plugs, wires, fuel filter, etc.? GM has acknowledged that your year and model Impala may have been delivered with a flaky CAT convertor. The CAT warranty was extended to 120K miles or 10 years, whichever comes first versus the intial 8 year/80K miles. The dealer can perform a CAT convertor efficiency/backpressure test to determine if it is a clogged CAT.

Do you have any unexplained coolant loss because the upper intake manifold gaskets are a known problem on the Series II 3800.

Also, try cleaning the throttle body with STP TB spray cleaner and the MAF sensor hot wire element with electrical contact cleaner.

bnaylor3400: Thanks for your response...

So far the only basic tune up items I have done is to replace the air filter and PCV valve... I have not changed the fuel filter yet, or any of the other items you mentioned... I know the plugs and wires on the back of the motor are a major pain in the butt to replace so I've been hesistant to do that...

I've learned from this forum about the flaky CAT converter so I want to check that out... Will the dealer charge me for the efficiency/backpressure test?

No unexplained coolant loss as far as I can tell... The overflow tank still has the proper amount in it... The car has 50K miles...

Cleaning the TB and the MAF sensor sounds like a good idea also... Does the screen pull off the TB intake?...What electrical contact cleaner do you recommend for the MAF sensor?... I assume this is the sensor snapped into the air intake just before the TB?

bnaylor3400: Thanks for your response...

So far the only basic tune up items I have done is to replace the air filter and PCV valve... I have not changed the fuel filter yet, or any of the other items you mentioned... I know the plugs and wires on the back of the motor are a major pain in the butt to replace so I've been hesistant to do that...

I've learned from this forum about the flaky CAT converter so I want to check that out... Will the dealer charge me for the efficiency/backpressure test?

No unexplained coolant loss as far as I can tell... The overflow tank still has the proper amount in it... The car has 50K miles...

Cleaning the TB and the MAF sensor sounds like a good idea also... Does the screen pull off the TB intake?...What electrical contact cleaner do you recommend for the MAF sensor?... I assume this is the sensor snapped into the air intake just before the TB?

The TB screen will come off easy. It is a big c-clip retainer. You can carefully pry it out. Gunk makes a MAF sensor spray cleaner. Autozone carries it.

The MAF sensor is located on the top of the throttle body. Black square module held on by two Torx safety screws and one electrical connector. Once MAF is removed you spray the bottom part that inserts into the throttle body.

On the CAT the dealer may charge you if the CAT is not found to be the problem or clogged/defective. If it fails backpressure test then the dealer should not charge you for the diagnostics or replacement of the CAT convertor. Right now you are covered under GM's 8 year/80K miles warranty on the CAT convertor having only 50K miles.

BTW - The sensor at the intake ducting is the intake air temperature sensor (IAT).

The rear plugs are a PITA but can be done with patience and the right tools. The worse part will be getting the spark plug boots and the metal heat shield off. I've never had to tilt the engine either. Good luck!

Excellent information... Thanks...

I'll update this post as I proceed...

I know I have asked this question before but what's the right way to disconnect the quick-connect fitting on the fuel filter?

I know I have asked this question before but what's the right way to disconnect the quick-connect fitting on the fuel filter?

You push in on the plastic clips (pawls) and then pull. See link below for guide and pics:

http://www.pfyc.com/supportfiles/gasfilter/

Good idea to relieve fuel pressure first. You can pull the fuel pump fuse in the engine compartment fuse box and let engine die out or use the Schrader valve on the fuel pressure regulator. Good luck!

Perfect!! Damn, you're good!!

Perfect!! Damn, you're good!!

Not a problem and you are welcome. Hope the info was helpful.

BTW - My wife had a '01 Impala LS but after tranny problems, etc. and getting stranded one day she traded it in. :dunno:

Not a problem and you are welcome. Hope the info was helpful.

BTW - My wife had a '01 Impala LS but after tranny problems, etc. and getting stranded one day she traded it in. :dunno:


Yeah, I've read your posts about your '01 IMPALA... I've just encountered another little problem today... Read my new post on my backwards parking brake light...

Update... I cleaned the TB and the MAF sensor and it actually made a difference... Better and smoother acceleration... Maybe not 100% of what it should be but much better... This week I'll be doing the fuel filter... After that I'll decide if I take it to the dealer for the CAT...

Update...

I replaced the fuel filter yesterday... It looked like the original filter and seemed to be very clogged... I was hopeful that this was causing the low power condition... But the car still has low power during acceleration... Tomorrow it goes to the local dealer to check for a clogged CAT converter...

Update...

I replaced the fuel filter yesterday... It looked like the original filter and seemed to be very clogged... I was hopeful that this was causing the low power condition... But the car still has low power during acceleration... Tomorrow it goes to the local dealer to check for a clogged CAT converter...

I bet a lot of us are curious as to how it turns out. Keep us posted on the results. Good luck!

OK... In addition to the low power issue they are also going to look into the parking brake indicator light that's working backwards... Think I'll "kill two birds with one stone" with this dealer visit??... I hope so!!

The car has been at the Chevy dealer ALL day today (after dropping it off there last evening)... I even included a detailed note about the low power problem and the suspected CAT converter... During two phone conversations they tell me they can't verify the problem and they can't verify a CAT problem... So I start to get angry on the phone and then all of a sudden the mechanic comes back from the shop saying "Oh yeah", "it is a clogged CAT!"... I took them 7 hours to finally reach that conclusion and now they have to order the part!!!... So now I don't get the car back until tomorrow (hopefully)... Now I'm off to rent a car that they will pay for!!!.... I'm starting to understand why GM is in so much trouble!!!... What a bunch of idiots!!!

Update...

I finally got the car back yesterday... They replaced the CAT and the car runs like a rocket again... It feels like a new car, very fast and smooth... It also seems to run a little cooler according to the temp. gage... Maybe I'll also see an increase in mileage?... So that's the good news... They also ordered me a new instrument cluster to fix the wacky parking brake light problem... But that won't be in until next week... Thank God I bought the GM Major Guard protection plan... Zero out of pocket expense... They also paid for the rental car...