Replace your Cat - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > Exhaust Mods

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Old 10-01-2016, 12:43 AM
el kabong's Avatar
el kabong el kabong is offline
2003 Chevy TrailBlazer LT
Dark Gray Metallic 4.2L I6 4X4
Join Date: Jun 2007
Location: L.A.
Posts: 113
Replace your Cat

My daughter has been driving our TB now almost exclusively since she turned 16, so almost 7 years now. Occasionally I would drive it, and I noticed the power was not there like it used to be, so I assumed it was just getting slowly worn out, despite dutiful maintenance on my part. A couple months ago, she said it could barely get up the hill road leading to our community, I drove it, jeez what a dog!! I asked how long has it been running this bad? Well maybe 6 months. WHAT!!!!?? Why didn't you tell me???!! Yeah and the gas mileage is really bad.
So long story short, it was a dog, and did not want to rev past 3-4k, really fell on its face when you gassed it. I did research here, and since it barely passed its last smog, I suspected the cat. It doesn't really use oil, and there is no exhaust smoke period either accelerating or on decel. But at 229k miles, something was up. I cleaned the air filter (K&N), ran seafoam in the tank and into the intake via the brake booster vaccum hose. I removed the battery lead, as it has a check engine light but no code on my scangauge? I replaced the fuel filter and just did both O2 sensors last year, (that sucked pay to have it done) Nothing helped.
I took it to a muffler shop and them welded in a new cat for $150 bucks. They showed me the old cat. Help up to the sun you could not see even one speck of light. 80% clogged they said. WHAT A DIFFERENCE!! I HAD MY OLD TB BACK!! This thing revved to 6 k easily, and all the power was back. My daughter was amazed, she was so happy her car was "back". I took the battery lead off again so it could relearn/reset and it got even better.
So my point is, if you have (how couldn't you?) over 100-150k on your TB have the cat replaced if you notice any of the symptoms I described. Such a cheap and easy fix, you might be surprised how well it runs again. I should have done it 50k or more ago, 2 years ago, kids just amaze me sometimes, even my own. DO NOT buy a GM cat they are ridiculously expensive. Leave this fix to a shop, its a piece of cake for them.
I cant wait to see how it does on its smog check this year. This bastard state of Kalifornia has been sending me to a Star certified only smog place the last 10 years, like they thought I must be cheating. They can stick it in their ear this next time.
3.73, G80, PCM tune, muffler, tranny cooler, K&N drop in., Mobil 1 since new.
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