2001 3.1L Century- loss of acceleration/power.

[meistermind]

Help!! I need some more suggestions. 2001 Buick Century, 3.1L, 148K miles.

Purchased a used Century about 4 mos. ago. Performed a tune-up, plugs wires, air filter, oil change. Car ran/drove good at the time, but was going through some oil. 2 mos later engine light came on (0420) related to the EGR- found the passage way in the plenum completley plugged and cleared it out and fixed code. I also replaced the intake manifold gaskets at the same time, which fixed the oil consumption. Car ran great for 2 more mos.

Just recently noticed having trouble going up hills on the highway, downshifting more often. Over two weeks, it has gotton progressively worse and now seems to lack the power to get the car up to any speed even from a stop. It will get going if I floor it and it downshifts, but it is still smoothly struggling as if towing a giant trailer. It will then slowly start to loose speed until I really step on it again. It does not buck or shudder, just seems like it is not getting enough gas or something is restricted. I am not loosing or crossing over any fluids. The cars starts and idles great, does not stall, and it revs up fine when in park- just under load is the weakness.

I have replaced the oil/filter again (synthetic), checked the air filter, new fuel filter, all 3 coils, changed tranny fluid/filter, tried several bottles injector cleaner. All had no effect and the condition is slowly getting worse. It does it cold or hot. The service engine light is not on and no codes thrown. I have had two codes thrown since it started, but I checked/cleared them right away each time and they have not come back yet. First code after changing oil and adding injector cleaner was 0410. Second while trying to accelerate down highway was 0404. Fuel pressure check w/key-on, engine off is 56psi; w/engine running is 50-52psi - both within specs.

Maybe my catalytic convertor is plugging up??- I saw another posting w/ similar problem and the cat fixed it. Would a plugged cat throw any codes?? I figure if an injector was bad, the car would run/start/idle poorly, and thus throw a code. Any ideas, tests would be helpful- Thanks

[BNaylor]

Bad CAT is a possibility. You may get DTCs or you may not. GM delivered certain 2001 - 2002 GM cars with flaky ones and extended the CAT convertor warranty.

You can get the CAT tested at the GM dealer or any muffler shop.

[meistermind]

Well, I decided to try a new catalytic converter a couple hours after posting this. I just finished and took the car for a test drive. Wow! what a difference. My problem is gone and the car runs better than ever, with plenty of power to spare.

I'm not looking for a race car with this Buick, but I drive alot of highway miles every week as part of my job. I buy a good used car every couple years, but I need something that is fairly comfortable to sit in for periods of time. This Buick does ride real nice and seems geared great for cruising at a nice pace.

Good Luck w/all your projects!!

[bezerk19]

Originally Posted by meistermind

Well, I decided to try a new catalytic converter a couple hours after posting this. I just finished and took the car for a test drive. Wow! what a difference. My problem is gone and the car runs better than ever, with plenty of power to spare.

I'm not looking for a race car with this Buick, but I drive alot of highway miles every week as part of my job. I buy a good used car every couple years, but I need something that is fairly comfortable to sit in for periods of time. This Buick does ride real nice and seems geared great for cruising at a nice pace.

Good Luck w/all your projects!!

Did you replace the catalytic converter yourself or a shop? Either way how much did you end up spending on it?

[meistermind]

Bezerk19,
I replaced the cat myself. I went online first to check availability and pricing. There are a loit of generic replacements, but they all require you to adapt it to your pipe configuration. I could do it, but it would have added a bunch of extra time and I would have had to piece in parts of pipe and flanges to make it fit right. I wnated a direct replacement, because I needed to get the car going (less down time). Also, I drive the car alot and wanted something tight, good fit that would last for a long time. The direct replacement went perfectly from one joint to the next and had the matching flanges/gaskets, so all I needed to do was cut/break the old flange bolts and put the whole new assembly in. I got some stainless steel new bolts from the hardware store. I had the old one off and the new one in, one evening, within a couple hours and beers. I bought the assembly from NAPA, seemed like everyne else had the generic replacements- I did not want to spend all weekend getting it to fit- loosely and fall apart in six months. It seems I spent about $300.00 - $350.00. (I noticed the Calaifornia model cost about double- he he, I'm in MI) They wanted $50.00 more at the store than the online price, but I talked them down on that. I have put 100K miles on the car, since and it has ran great at all speeds and the cat is working great, tight and quiet, and is in great shape. Well worth the $$ I spent for a easy fix that I haven't had to mess with again. - Good Luck on yours.........

[meistermind]

BTW,
Another reason I got the direct replacement is because it also has the threaded bung holes for the O2 sensors, and in the right location. You will need to transfer these over from the old assembly to save $$ and make it work right with your cars computer. I wanted the car to run right and not have the "check engine" light on. The generic cats don't have provisions for the 02 sensors.

[bezerk19]

Originally Posted by meistermind

BTW,
Another reason I got the direct replacement is because it also has the threaded bung holes for the O2 sensors, and in the right location. You will need to transfer these over from the old assembly to save $$ and make it work right with your cars computer. I wanted the car to run right and not have the "check engine" light on. The generic cats don't have provisions for the 02 sensors.

Yeah i found a direct fit from O'reilly auto parts, for $177, took it to a local muffler shop and got it replaced for $50, now the car runs great!