2001 Buick Century 3.1 66k miles, Very sluggish

[TGP37]

Spark plug non-fouler

Anything else won't work. Unless he is building a circuit to interact with the PCM. Or he has a tuner that can turn off the o2 sensor from reporting an error.

[bigboi407]

That noise, could be the timing chain, loose metal. It may be metal debris in front of the cat. It could be the cat itself. It could be a bolt resting on a heat shield.

Don't start spinning in circles. One thing at a time. Swap the cat and go from there.

I would also try some top end cleaner. I use seafoam, others use other stuff, but it's all similar. IF the cat is clogged I'd imagine the EGR has been over worked and lots of soot made it's way into the intake.

The noise COULD be a loose, stretched timing chain. But it's pointless to dig deeper until the cat is swapped.

Trust me Im not spinnin in circles..... i was a little frustrated with this car, but im past that and really at the point where i dont care if i can fix it or not, if i can, i can but im not gonna hold my breath, i guess her mother handed her a sour lemon (And Yes on purpose)

i did run seafoam through the engine, but i did 1/3 of the can through the booster hose, cut the car off for 5 minutes, and cranked it on, let it sit for another 5 minutes then drove it around and the white smoke only lasted about 1/4 mile or so.

today im gonna pull down the cat, gut it and let my brother work his magic, he says the hell with a new cat because he knows he can trick the 2nd sensor to read as if it has a perfect working Cat.. i will report later today with my results

[TGP37]

That noise, could be the timing chain, loose metal. It may be metal debris in front of the cat. It could be the cat itself. It could be a bolt resting on a heat shield.

Don't start spinning in circles. One thing at a time. Swap the cat and go from there.

I would also try some top end cleaner. I use seafoam, others use other stuff, but it's all similar. IF the cat is clogged I'd imagine the EGR has been over worked and lots of soot made it's way into the intake.

The noise COULD be a loose, stretched timing chain. But it's pointless to dig deeper until the cat is swapped.

[bigboi407]

MAF readings dictate line pressure in the transmission, and fueling. stating that you have installed a K&N filter element can cause an issue that i have seen before aswell, which is the oil in the filter element collects on the MAF sensors, some replace the sensor, i have cleaned it with a SENSOR SAFE cleaner, and a q-tip, and the vehicle was 100% after.

Now, i have not read every single post, but you seem to hopping around doing the CAT, you have a replacement, you dont, now your gutting it... now, i dont know everything, but the things that i have mentioned i do know.

TGP has a point with the motor burning antifreeze, causing the CAT to plug, and this can be from the most common issue with these motors which is the LIMG or a cracked head, or leaking head gasket, but there are easy tell tale sings which are white sweet smelling smoke from the exhaust, milky dirty oil, and low coolant levels. and the car will run like shit and over heat if any of these problems are present. Your issue is a loud as hell intake sucking noise, i had the same exact issue with my car, and discribed it the same. threw me for a loop, i thought for sure the LIMG's finally went on my car, but no, it was the CAT. it was replaced under warrantee and the problem was gone, car was loud, went fast-er, and shifted better.

Also, TGP is again right about the trans shifting issues and low fluid levels, but you will see that you dont have 4th gear, or 3rd pending on how low of fluid you are, its got a latter effect, the lower you are, the less high of a gear the trans will shift into.

its not that i have been hopping around doing the CAT, Its her car and i dont live with her, i dont work because my back is shot and cant work even if i was given a job cause i cant stand for long periods of time and i have sciatic nerve damage, so every few weeks i cant walk. that being said with low income things have to be done cheaply....

im getting her car over here tomorrow, I HOPE, so i can tackle the Cat once and for all

My dad Double checked the tranny fluid level for me, he confirmed that it is perfect, Then he played with the throttle and he seems to think that the motor is being restricted by more than just clogged exhaust, Check out these videos below... We both Clearly understand that the engine is being restricted due to a clogged cat, but whats this knock sound?






there is no water in the oil or oil in the water, all fluids are where they should be... when i blew the head gasket in my CRX i had emulsified gray goo in the radiator, no such thing has occured in this buick..

Note: i started to think about this Century, and it has NEVER Ran anywhere near as good as my friends lumina in the time she has own the car, yeah it used to drive pretty good, but it has never set me back in the seat, nowherere close to like the lumina did, she got her car with 50k miles from her mom.. the lumina i speak of has well over 100k

[bob442]

MAF readings dictate line pressure in the transmission, and fueling. stating that you have installed a K&N filter element can cause an issue that i have seen before aswell, which is the oil in the filter element collects on the MAF sensors, some replace the sensor, i have cleaned it with a SENSOR SAFE cleaner, and a q-tip, and the vehicle was 100% after.

Now, i have not read every single post, but you seem to hopping around doing the CAT, you have a replacement, you dont, now your gutting it... now, i dont know everything, but the things that i have mentioned i do know.

TGP has a point with the motor burning antifreeze, causing the CAT to plug, and this can be from the most common issue with these motors which is the LIMG or a cracked head, or leaking head gasket, but there are easy tell tale sings which are white sweet smelling smoke from the exhaust, milky dirty oil, and low coolant levels. and the car will run like shit and over heat if any of these problems are present. Your issue is a loud as hell intake sucking noise, i had the same exact issue with my car, and discribed it the same. threw me for a loop, i thought for sure the LIMG's finally went on my car, but no, it was the CAT. it was replaced under warrantee and the problem was gone, car was loud, went fast-er, and shifted better.

Also, TGP is again right about the trans shifting issues and low fluid levels, but you will see that you dont have 4th gear, or 3rd pending on how low of fluid you are, its got a latter effect, the lower you are, the less high of a gear the trans will shift into.

[bigboi407]

Do the CAT, do the fuel pump, and dont bother posting again till its all done also clearing the computer, or diconnecting the batter for a hour will help. you will have weird trans shifting issues due to the MAF having scewed readings because the CAT is plugged. remember, a motor is just a heart, an intake and a exhaust, if one is plugged or has restricion, you will have issues. Then you die.

Sir, i do not mean to be a prick/smart ass by saying this but you obviously havent been reading my thread entirely.... i installed a BRAND NEW fuel pump, the cat will be gutted/modded tuesday

i was also never told "you will have weird trans shifting issues due to the MAF having scewed readings because the CAT is plugged" until now

Once again the things that have been done below:

New K&N Air Filter
New AC Delco Spark Plugs
New Bosch Wires
Cleaned MAF
New Fuel Filter
New MAP sensor
New Fuel Pump

[bob442]

Do the CAT, do the fuel pump, and dont bother posting again till its all done also clearing the computer, or diconnecting the batter for a hour will help. you will have weird trans shifting issues due to the MAF having scewed readings because the CAT is plugged. remember, a motor is just a heart, an intake and a exhaust, if one is plugged or has restricion, you will have issues. Then you die.

[bigboi407]

The trans is commanded to shift determing few things. It must not be in P/N, both RPM and MPH limits are reached for shifting and the trans is functioning properly.

I remember noting the auto trans fluid. If the level is too high or too low the trans WILL not operate properly. Many functions rely on the ATF being proper. As in it can not be burnt and must have the right amount. Also, too many people will balance the ATF from the dipstick reading when cold and off.

The shift is done by fluid pressure acting on a piston under springs. Low fluid will prevent the piston from being pushed, too much fluid will make bubbles and bubbles compress preventing the piston from shifting proper. The auto trans is connected to the crank via fluid. There is no solid connection, the ATF is used to transfer power from the crank to the trans. Burnt fluid, bubbled fluid, low fluid will hinder that.

The only way to properly fill the auto trans is to do so while the trans is hot (warmed up from driving) and the engine ON. otherwise the fluid level will not be correct.

If the fluid level is not correct, you will have shifting problems, you will have a lack of power, the car will burn a lot more mpg in fuel.

Don't assume anything, and tell me, did you check the ATF level when the fluid is warm and the engine is running? Is the fluid red or brown and smells burnt? Seriously, 1-2 qts too low and you'll have all kinds of trans issues.

i did note in a previous post that i used TransTune in the transmission, the fluid had bubbles in it before the trans tune, drove it around 10 miles, and i dropped the pan, replaced the filter and pan gasket, i filled it up with brand new fluid to the correct level took it around for a spin, and it drives much better than it did before, The transmission has been opened before by a shop, when i dropped the pan the magnet had a good amount of metal on it

and yes i drove it around and double checked the level to make sure its in the right spot, i know with the engine off gives an innacurate reading,

the engine in my friends lumina Sounds SOOOO much stronger and better than the 68k mile 2001 3.1, i was test driving his lumina because it dies when it comes to a stop so i was punching it from a stop, a pony GT got next to me and the guy happened to had been looking around for someone to play with, i punched the accelerator in the lumina and left em behind, the guy in the pony didnt wanna come anywhere near the lumina my friend that owns the car was laughing at him,

this thread is getting kind of long and the topic of issue is changing im debating on making another detailed thread so were all on the same page

[TGP37]

The trans is commanded to shift determing few things. It must not be in P/N, both RPM and MPH limits are reached for shifting and the trans is functioning properly.

I remember noting the auto trans fluid. If the level is too high or too low the trans WILL not operate properly. Many functions rely on the ATF being proper. As in it can not be burnt and must have the right amount. Also, too many people will balance the ATF from the dipstick reading when cold and off.

The shift is done by fluid pressure acting on a piston under springs. Low fluid will prevent the piston from being pushed, too much fluid will make bubbles and bubbles compress preventing the piston from shifting proper. The auto trans is connected to the crank via fluid. There is no solid connection, the ATF is used to transfer power from the crank to the trans. Burnt fluid, bubbled fluid, low fluid will hinder that.

The only way to properly fill the auto trans is to do so while the trans is hot (warmed up from driving) and the engine ON. otherwise the fluid level will not be correct.

If the fluid level is not correct, you will have shifting problems, you will have a lack of power, the car will burn a lot more mpg in fuel.

Don't assume anything, and tell me, did you check the ATF level when the fluid is warm and the engine is running? Is the fluid red or brown and smells burnt? Seriously, 1-2 qts too low and you'll have all kinds of trans issues.

[bigboi407]

Cats can get clogged by silicon deposits from leaking coolant. They can also plug up from running too rich for a length of time.

There are things called Test Catalytics which look like cats but are actually straight pipe inside. Though I like the tone a cat adds to the exhaust note.

Be sure to scrap that old cat. Might get anywhere from $50-90 for it.

okay, i just drove my friends Chevy lumina, it has a 3100 and it HAULS ASS compared to my girlfriends Century, m gonna try gutting the cat and rigging the 2nd o2 sensor to run without the cat guts, what do i got to lose?

What would cause the transmission to not shift from 1st to 2nd while the gas pedal is all the way down, because his car takes off like a rocket, shifts through the gears fine, isnt throwing any codes, im gonna assume theres another problem i am not adressing because his Lumina IS VERY VERY Fast Versus the Century, his Lumina dies when it comes to a stop and when i put it in Drive from park, what would cause that? it takes off like a rocket if the pedal is floored, when driving if i press very light the transaxle will rock, i may make another thread for his vehicle

i hope we can get the Century fixed to run as good as his Lumina, i dont wanna throw in the towel with the buick, but if i cant get it to run normal, whats the point of keeping it

[TGP37]

Cats can get clogged by silicon deposits from leaking coolant. They can also plug up from running too rich for a length of time.

There are things called Test Catalytics which look like cats but are actually straight pipe inside. Though I like the tone a cat adds to the exhaust note.

Be sure to scrap that old cat. Might get anywhere from $50-90 for it.

[bob442]

the guy i had sold my new down pipe to had a 02 century, and he had the same problem, gutted the cat, tide up the O2 so it read 'properly' and the thing still ran like crap, once he put mine in, he called me back and said the thing has never ran so good. Just a heads up.

[bigboi407]

Two ways you can approach this.......

Remove the cat by unbolting the exhaust upstream and downstream. It will be a length of exhaust pipe. Cut the old cat out. Try to cut out a length equal to the length of the replacement cat. Keep in mind you will want an inch extra on each side for overlap. So if the replacement cat is 14" long, cut out 12" worth of space with the old cat. If the replacement is too short, get some pipe at any autoparts store. Keep in mind you want overlap so pay attention to inner diameter versus outer diameter.

You then will want to clamp it well. Don't use the cheap horseshoe like clamp. Get a band clamp for overlapping joints. They seal better.....but if you can get it welded, do it.

Do NOT use the flex pipe found in Advance Auto Parts. It leaks after time and the Cat gets REALLY hot. So do not use anything but metal. No RTV or any other non metal gaskets.

Great band clamp for something like this. You do not want a leak under neath the chassis. It WILL get into the cab easily an poison you over time.

If it is a direct fit, you gotta simply unbolt it.

All of this means you will be under the car. Be sure to use proper jack stands on solid, level ground. Do NOT get under the car with just jacks holding it up. A big guy like you won't stand a chance if it falls on you. Don't be a statistic, be safe.


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thank you for all ur help, i spoke with my brother and hes gonna assist me in gutting the cat and rigging the 2nd O2 sensor so it reads as if the cat is still inside and working, we live in Florida, theres Nothing about emissions here, hence why i never knew a cat could cause so much trouble, ive never had a vehicle with one installed, besides my 91 lesabre and i didnt drive it for that long either

if i were to buy the magnaflow one in the future it is a 100% Direct Fit no cut required cat... i have more rims/tires than you can shake a stick at, so i use some to make sure if it does fall it lands on tires and not on me... i can go under cars and have for many years, but with my back problems i try to avoid anything that would cause me to be stuck in bed with sciatica which includes working under cars or bending down into the engine bay, hell i cant even stand for more than 20 mintues... but im not gonna pay someone to work on my car or her car bcause i dont trust anyone elses work, UNLESS its something i absolutely cannot stand to do or just dont have the tools with power to complete the job at hand, but i have a guy i buy tires from that will do anything i pay him to do

the worst danger ive encountered in mechanic work at home was a complete D15 Honda engine falling from the engine crane and it bounced off my knee before it put a chip in the concrete below..... luckily it didnt break anything and i had jeans on, or id have deff been screwed, i always make sure stands are in a spot where the car if even shaken wont budge off the stand, aside from that incident, ive had plenty of knuckle busting experiences, or how id like to call it "The Craftsman Snap!" never in my life will i ever buy craftsman (my dad did), we have a 3/8" snap on rachet that has outlived all the craftsman rachets including the big torque wrench, hell ive got 3 broken Craftsman rachets i havent taken back because i know how much they suck

[TGP37]

Two ways you can approach this.......

Remove the cat by unbolting the exhaust upstream and downstream. It will be a length of exhaust pipe. Cut the old cat out. Try to cut out a length equal to the length of the replacement cat. Keep in mind you will want an inch extra on each side for overlap. So if the replacement cat is 14" long, cut out 12" worth of space with the old cat. If the replacement is too short, get some pipe at any autoparts store. Keep in mind you want overlap so pay attention to inner diameter versus outer diameter.

You then will want to clamp it well. Don't use the cheap horseshoe like clamp. Get a band clamp for overlapping joints. They seal better.....but if you can get it welded, do it.

Do NOT use the flex pipe found in Advance Auto Parts. It leaks after time and the Cat gets REALLY hot. So do not use anything but metal. No RTV or any other non metal gaskets.

Great band clamp for something like this. You do not want a leak under neath the chassis. It WILL get into the cab easily an poison you over time.

If it is a direct fit, you gotta simply unbolt it.

All of this means you will be under the car. Be sure to use proper jack stands on solid, level ground. Do NOT get under the car with just jacks holding it up. A big guy like you won't stand a chance if it falls on you. Don't be a statistic, be safe.

[bob442]

lube the bolts, take a 15mm deep socket and extensions and a ratchet. Raise car atleast 1 foot, crawl under car. if you got a new cat, then you have to cut the old one out, if you got a new downpipe with cat, then its a bolt on. Technically, you could "bolt on" a cat, but that involves using those grabage clamps. people who use those should be shot.