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2005 chevy trailblazer_ls_ext
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305 Posts
What exactly is this CC assembly you speak of?

I'll add my experience here.

I was having the same symptoms as the OP with my 2002 Envoy XL SLT. From reading Trailvoy, I was pretty sure it was also my catalytic converter. It was really starting to have major problems with taking off from stops and I've even gotten a better idea of what streets in my city has the biggest hills as my power would really bog down if I had to make it up an incline. For several weeks there I was driving in the slow lane.

I was able to find the catalytic converter on Amazon for $200... with free shipping. For the XLs make sure you get the CC assembly for the longer wheelbase, btw. Another $120 in labor charges with the local shop close to my neighborhood and my GMC Envoy now runs like a champ again.

Hopefully this helps somebody. I know I've gotten a LOT from this site in the short time that I've owned my Envoy, so hopefully I'm giving back a bit here.

Love the site!!!
 

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2004 chevy trailblazer_lt
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2 Posts
HI Everyone!! Need some help with the cat converter

Hi Everyone-

I know this is an older post, so I hope someone can still see this and help me out!

I have a 2004 Chevy Trailblazer and have been having a hard time diagnosing the issue in my car:

Symptoms:

-hesitation/bucking when accelerating
- sometimes feels like not as much power getting to engine

So last night I was on the Mass Pike and was driving along and thought I heard a noise from the undercarriage and then I stepped on the gas and the RPM"s shot way up, but the car wasn't accelerating. A friend of mine said it was her cat converter when she had a similar issue on the highway with her 2002 Chevy Imapla.


Thoughts???
 

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2003 chevy trailblazer_ls
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525 Posts
If you want a quick way to prove the cat converter bad, remove the O2 sensor from the manifold and drive it around. Removing the sensor gives the exhaust a way out. It will be a little loud and will throw a code but if you regain power then your cat is bad. Also check your temp gauge, it should be straight up at 210. If its not then the PCM will dump more fuel into the engine to heat it up. A rich condition consistently will destroy cat converters and O2 sensors as well as give you terrible mileage.:m2:
 

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2003 gmc envoy_slt_xl
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18 Posts
Catalytic converter replacement

Today I just finished a long journey with my Envoy. The last weekend of October we were traveling to Orlando with a trailer load of household goods for my son. About two hours in the engine started to loose power and thru a code. I stopped at a local Auto Zone to check it out, got a rich code on bank one and two O2 sensors. Went on our way with poor MPG and losing more power. Mileage went down to less than 5 mpg. Finally the engine wouldn't pull more than 5 mph. Limped off I-10 and got a tow to Madison Fl.. After a replaced mass Air flow sensor and fuel filter the mechanic came up with the Cat. plugged up. Cut an inspection port and cleaned out the clogged guts and welded it back up to get us on the road. Made it to Orlando and back home. Got the new cat in today. If you want to attempt this make sure you have an air impact wench for the stubborn bolts and nuts. LONG extensions for the sockets. You will have to support the transmission and remove the cross member. Spend the extra money and replace the post cat O2. BTW the connector is on top of the transmission. 8 hours and lots of head banging:duh: I got the job done and test drove it. The power is back. :thumbsup: I used this Cat. Walker 55477 Direct Fit Converter on Ebay for $176.80.
 

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2004 gmc envoy_slt
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Catalytic Converter problem

Hello, I've been experiencing rough idling stalling, poor acceleration and an engine light blinking so I took it to the dealer and they replaced my O2 sensor, all spark plugs and coils on my 2003 Envoy SLT with 225,000 Km on it. I've recently starting hearing louder than normal muffler noise and my engine light always on. The dealer has advised me that, I needed a new catalytic conveter after doing some diagnostics. How long can I run my Envoy with a bad Cat? Will it have any other issues later on if I don't replace it right away?
 

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2003 chevy trailblazer_ls
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525 Posts
At the risk of sounding like a smart ass, asking how long can you run it is like asking how long you can live with clogged arteries. Nobody really knows the answer. What side effects could you have from running it too long with a bad cat? Well it will become increasingly sluggish due to the restriction causing you to mash the gas harder to get it moving and maintain speed. That being said I would think bad gas mileage, O2 sensors would be just a few problems. Eventually it will get so clogged that you would go into limp mode or begin stalling alot and get you stranded. Dealers can be expensive and most try to sell a bunch of stuff you don't need. A good replacement cat that has been used with much success is http://www.summitracing.com/parts/MPE-53006/. I am not sure if pricing is current. You can check with a local muffler shop and see how much it would cost to get it welded.:m2:
 

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2003 chevy trailblazer_lt
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12 Posts
CAT Temperatures

:bonk:My 03 Trailblazer has been losing power lately. Checked all of the obvious things replaced Air Filter, Fuel Filter and even new plugs. Still same issue once it warms up loses power going up hills. I started reading through these forums and came across the Bad CAT issues. I checked the input and output temps with my Fluke IR and the input temp was 500 degrees and the output temp was 500 degrees? Any ideas? Or did I just answer my own question that it needs to be replaced?
 

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2003 chevy trailblazer_lt
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Replacing the CAT

:bonk:My 03 Trailblazer has been losing power lately. Checked all of the obvious things replaced Air Filter, Fuel Filter and even new plugs. Still same issue once it warms up loses power going up hills. I started reading through these forums and came across the Bad CAT issues. I checked the input and output temps with my Fluke IR and the input temp was 500 degrees and the output temp was 500 degrees? Any ideas? Or did I just answer my own question that it needs to be replaced?[Assuming no input equals replace the CAT. Ordered one yesterday will post if it was the culprit.:crazy:]
 

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2003 chevy trailblazer_lt_ext
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O2 sensor removal for test

This site is excellent! I've only been on for a short time and already have a new wealth of answers to questions I wasn't aware I had.
We bought our 03 EXT TB LT with 105k miles and it never seemed to have any power. I attributed this to a large vehicle with a six cylinder.
A couple of weeks ago, my wife told me saw some hair out of the exhaust. I was excited because I figured that was the cause of the low power. So, after reading some posts, I cut off the resonator! No improvement. So, I had seen in another post to remove the upstream 02 sensor. Problem being, I don't know to remove the sensor in a way to put it back in after it runs removed. I am confident that the cat is plugged, but would like to be sure.
Thanks in advance.
 

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2004 gmc envoy_slt_xuv
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Well I did a vacuum test on engine today, trying to determine if I have excessive back pressure.. attached is the video of the gauge. To those who dont want to see video.. Overall I lost about 3 inches vacuum, from idle to 3000 rpm.

Is any decline indicative of excessive back pressure? or is there a certain limit?

http://www.youtube.com/watch?v=l8gvVUZ7wjU
 

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2003 chevy trailblazer_lt
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12 Posts
Magnaflow CAT

Received the Magnaflow CAT and had it installed today. After the old one was cut off found basically the guts were completely gone. No wonder I had the same temp on the input as well as the output. After a break in period will check the temps again to see where I am at with this new CAT.;)
 

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2002 chevy trailblazer_lt
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51 Posts
Cat Converter gone bad again.

I have '02 trailblazer,:crazy: and I replaced the Cat Converter two years ago. I only have about 30k on the replacement. The replacement has recently gone bad too. Has anyone had problems with replacement cat's?
 

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2003 chevy trailblazer_lt
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I have '02 trailblazer,:crazy: and I replaced the Cat Converter two years ago. I only have about 30k on the replacement. The replacement has recently gone bad too. Has anyone had problems with replacement cat's?[What brand was it you had installed 2 years ago?]
 

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2002 chevy trailblazer_lt
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51 Posts
Don't know what the brand name that was installed two years ago, but the warranty was only good for one year. I found that the Magnaflow warranties there cat's for 5 years or 50K miles.:worried:
 

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2002 chevy trailblazer_lt
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51 Posts
Running on a bad cat converter

Does anyone know if you do more damage to the engine if you continue to drive with a bad catalytic converter? I am not due for inspection until January 2014. Thanks!:cry:
 

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2004 chevy trailblazer_ls_ext
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We had damage occur to our exhaust manifold (it cracked) and found
out later that it was probably due to excessive heat build up from
a clogged cat converter.
 

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2002 chevy trailblazer_ls
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O2 sensors vs Cat converter

Hi Jimmyjam, I thought if you removed the O2 sensors and the power returns, it was the O2 sensors? :confused: If the stuck open tstat is the causing problem for the cat clog, should you install a new tstat or can that be fixed? I have noticed a slight decrease in acceleration and a change in gas mileage in my 02 TB. I used octane booster and noticed an improvement in my gas mileage, but it's still not right. I also had an oil change using a FRAM High mileage oil filter (since it was put in I have heard bad things about that type of filter); could that be the problem? The oil filter makes the engine sound like a 18 wheeler!:confused:

I love this site; am learning a lot about my 02 trailblazer!

a plugged cat is easily diagnosed. unscrew the upstream o2 sensor from the exhaust manifold and go for a short drive. if the power returns, then get a new catalytic converter. and fix whatever caused it to clog in the first place (stuck open tstat probably)
 

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2003 gmc envoy_slt_xl
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Clogged Cat - old topic - new question?

Hi all, I have searched through most if not all posts looking for my situation to probably what caused my cat to clog.
After arriving at work [ 30 km of freeway/highway commute], I spend the rest of the day on short runs of a few minutes each to get from one building to the next servicing machines, my Envoy never reaches good operating temp.
After I change the cat and follow some other suggestions like change thermostat etc. Should I consider a lower or perhaps a higher temp thermostat to better generate heat for the motor on short all day runs?
Kinda confused - or just accept that that this is wear and tear based on my job?

thnx guys -
 
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