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2005 chevy trailblazer_lt_ext
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Discussion Starter · #1 ·
I have a 2005 trailblazer ext with the 4.2 and 107,000 miles. I have noticed here lately it seems to be lacking power. I have cleaned the K&N filter today and the throttle body was cleaned in April before we went to FL. It drivers alomost like my 4 cyl Jeep did when the cat converter clogged up. I have no dash lights on. Its getting 12-13 in city and 16-18 on highway so mpg seems close to normal. I just replaced all brakes and dont believe I have a calplier dragging and they dont smell hot after a trip.
It has been reading a little warmer on the Temp gauge then what I remember and was actually about a needles width above 210 pulling my boat in town. The boat and trailer are about 3500 lbs and it was about 90 out.

Any ideas??????:weird:
 

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2005 chevy trailblazer_lt_ext
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Discussion Starter · #3 ·
I changed the plugs at about 80,000 to bosch platnium +4's. After reading here maybe that wasnt a good choice. I may have the cat conv tested and if that comes back ok I'll have to look at some other things.
 

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2005 chevy trailblazer_lt_ext
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Discussion Starter · #7 ·
Nope no warning lights on the dash at all. I had a exhaust manifold leak reparied at about 90,000 and the cat conv rattled for about a month then quit when i went to FL and ran it 15 hrs one way....maybe it finished it off? not sure but doesnt look like any easly installed aftermarket exhaust for ext...my luck.....I dont have a welder or tube bender
 

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2003 gmc envoy_slt_xl
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Nope no warning lights on the dash at all. I had a exhaust manifold leak reparied at about 90,000 and the cat conv rattled for about a month then quit when i went to FL and ran it 15 hrs one way....maybe it finished it off? not sure but doesnt look like any easly installed aftermarket exhaust for ext...my luck.....I dont have a welder or tube bender

Hi,

1- If the cat is clogged, you'll get an always overheating engine. SES will come on at 15 minutes constant 30m/h driving. Check it out.
2- Get the original spark plugs first.
3- Check the fuel pump pressure. Should be 60psi.
4- If cheap, replace the fuel pressure regulator.
5- Clean or replace the air filter.
6- Cracked exhaust manifold causes this also.
7- Dirty injectors may cause the problem, but you'd have a jerky engine.
If all the above didn't work, you might need to check the engine compression.
 

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2002 olds bravada
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2,369 Posts
Just change the plugs to Delco Iridium's and run a good fuel injector cleaner through the tank (seafoam, techron, etc).

I had the Bosch +2 Platinums for a couple thousand miles. When i put them in, it made a good difference, but went away after 100 miles. I pulled them out about 5 thousand miles, they all had bent tips.

Also, keep in mind that our trailvoys came with double platinum plugs from the factory. If you go with platinum's, its like downgrading..
 

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2003 chevy trailblazer_lt
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130 Posts
Keep in mind also that if you have any chip upgrade the life even with high perforance plugs they will wear due to the high temp as wellas with the iridiums mine were shot I have the stage 1 jet so check them ever 5k
Just change the plugs to Delco Iridium's and run a good fuel injector cleaner through the tank (seafoam, techron, etc).

I had the Bosch +2 Platinums for a couple thousand miles. When i put them in, it made a good difference, but went away after 100 miles. I pulled them out about 5 thousand miles, they all had bent tips.

Also, keep in mind that our trailvoys came with double platinum plugs from the factory. If you go with platinum's, its like downgrading..
 

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2005 chevy trailblazer_lt_ext
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Discussion Starter · #11 ·
Well I changed the plugs back to the Delco and what a difference. I guess they were the Iridium's $15.00 each but they sure made a difference. I also cleaned the throttle body again so the battery was unhooked for about an hour as I changed the plugs and cleaned the throttle body. Even the wife noticed a difference.
 

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2003 chevy trailblazer_ltz
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Clogged cat won't necessarily overheat the engine. My engine temps were fine but the truck would barely go. I drove it in 3rd on the highway just to keep up the same speed up hills. I gutted the cat to test and the truck had power like never before. Gas mileage jumped 4-5mpg. I've got a new cat on order but it let me confirm my suspicions for free.
 
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