Tiggerr
Member
Only getting 160 miles on 25gal tank
- Thread starter pcharm129
- Start date
Tiggerr
Member
Hell yeah it can. Can cause engine damage, set your floor on fire. Lots of bad things can happen from a plugged up cat. I've seen both those things happen with my own eyes.pcharm129 said:
djthumper
Administrator
With everything that you have said you have done and gone through... The odds are that you have a very clogged catalytic converter.
Mounce
Member
littleblazer
Member
- Jul 6, 2014
- 9,265
If you'd like, autozone or advanced auto parts should have the tester on loan, if you would prefer that.
Sparky
Member
- Dec 4, 2011
- 12,927
I have a friend who's old Bonneville's cat clogged up and the thing ran like crap, MPG started dropping, and then it got really bad all of a sudden and the cat would literally glow red. It burned off the weeds growing through his gravel driveway lol. I'm surprised it didn't burn his carpet.
Tiggerr
Member
Chickenhawk
Member
- Dec 6, 2011
- 782
In all the years I have been on this and other forums, I think there are two almost-certainties that can almost be diagnosed by reading just the first post:
- if the temp gauge is consistently reading to the left, it needs a new thermostat or coolant temp sender. If it is steady to the left and has been for a while, it is likely the thermostat. If it has just started and the needle wavers a bit on the highway when it should be steady, it is the sensor. In most cases, it is best to change both.
Many people point out that the gauge is not 100% accurate, nor does it read linear. It doesn't matter; if it reads to the left, it needs to be fixed.
- if the temp gauge has been reading to the left longer than a month or so, you will need a new cat, sooner or later. Cats run a very fine ratio, and the slightest bit of deviation because of a bad temp or a bad temp reading (either one dumps a LOT more fuel into the engine when it doesn't need it) and the cat is cooked or will be cooked shortly.
Cats do not repair themselves. If you are lucky and catch it right away, you may be okay. It will usually get worse. Symptoms of a bad cat include poor acceleration, especially accelerating up to highway speed on an on-ramp. These trucks are not dogs; they should take off.
If poor acceleration is felt only at low speeds such as in first gear, and it normally goes like a rocket when accelerating from 30 to 70, then suspect the transmission instead of the cat.
It is almost NEVER the fuel filter. (The most oversold product in America, next to nitrogen for tires.)
Trust me; as these platforms age, we will see more and more people experiencing a problem that they don't even know about. Performance and mileage both drop off slowly until they realize one day it just doesn't seem to have the same pickup as when new. Well maintained vehicles should NOT slow down just because they are getting older.
While taking the oxygen sensor out is one way to tell if you have a really plugged cat, and some muffler shops measure the cat temperature, the only sure way to tell is to remove the front oxygen sensor and replace it with an exhaust backpressure gauge. This is simply a pressure gauge, but designed to read low numbers such as 0 to 8 PSI. It should read 0 at idle and no more than 1 or 2 at 2500 RPM. Many muffler shops will do this test for free because they are expecting to get the work. Get them to show you the readings.
By the way, the gauges are not expensive. I bought my own for $120. With two Trailblazers in the family, I expect I will need it one day.
- if the temp gauge is consistently reading to the left, it needs a new thermostat or coolant temp sender. If it is steady to the left and has been for a while, it is likely the thermostat. If it has just started and the needle wavers a bit on the highway when it should be steady, it is the sensor. In most cases, it is best to change both.
Many people point out that the gauge is not 100% accurate, nor does it read linear. It doesn't matter; if it reads to the left, it needs to be fixed.
- if the temp gauge has been reading to the left longer than a month or so, you will need a new cat, sooner or later. Cats run a very fine ratio, and the slightest bit of deviation because of a bad temp or a bad temp reading (either one dumps a LOT more fuel into the engine when it doesn't need it) and the cat is cooked or will be cooked shortly.
Cats do not repair themselves. If you are lucky and catch it right away, you may be okay. It will usually get worse. Symptoms of a bad cat include poor acceleration, especially accelerating up to highway speed on an on-ramp. These trucks are not dogs; they should take off.
If poor acceleration is felt only at low speeds such as in first gear, and it normally goes like a rocket when accelerating from 30 to 70, then suspect the transmission instead of the cat.
It is almost NEVER the fuel filter. (The most oversold product in America, next to nitrogen for tires.)
Trust me; as these platforms age, we will see more and more people experiencing a problem that they don't even know about. Performance and mileage both drop off slowly until they realize one day it just doesn't seem to have the same pickup as when new. Well maintained vehicles should NOT slow down just because they are getting older.
While taking the oxygen sensor out is one way to tell if you have a really plugged cat, and some muffler shops measure the cat temperature, the only sure way to tell is to remove the front oxygen sensor and replace it with an exhaust backpressure gauge. This is simply a pressure gauge, but designed to read low numbers such as 0 to 8 PSI. It should read 0 at idle and no more than 1 or 2 at 2500 RPM. Many muffler shops will do this test for free because they are expecting to get the work. Get them to show you the readings.
By the way, the gauges are not expensive. I bought my own for $120. With two Trailblazers in the family, I expect I will need it one day.
- Aug 15, 2012
- 191
Ok. So i haven't gotten a chance to do anything physical to the truck yet (gonna get to that hopefully 2moro). But i did take the following screenshots of Torque yesterday. I have no idea what most of the info means. But i figured it may be helpful to you guys. The more info the better, right?...
Dial positions when truck is off...
View attachment 67854View attachment 67855
Idling for 15 min...
View attachment 67856
Torque screenshots...
View attachment 67858
View attachment 67859View attachment 67860
View attachment 67861View attachment 67862View attachment 67863View attachment 67864View attachment 67865
Dial positions when truck is off...
View attachment 67854View attachment 67855
Idling for 15 min...
View attachment 67856
Torque screenshots...
View attachment 67858
View attachment 67859View attachment 67860
View attachment 67861View attachment 67862View attachment 67863View attachment 67864View attachment 67865
Blckshdw
Moderator
Mounce
Member
- Aug 15, 2012
- 191
I can't seem to be able to post the images. I've been trying for over an hour now. Tried resizing them. And tried jpeg and gif formats. No luck. I tried drag and drop, and i tried uploading the files. Drag and drop places them in the text area, but when I try to post, it says, "You are not allowed to use that image extension on this community." Am I doing something wrong?
Mounce
Member
Could be an issue that a moderator or admin would have to straighten out in your settings.
Other than that, you could make an account on imgur or photobucket, upload the pictures there, then share them here via links, they should automatically embed and it'll look just like you uploaded them here.
Other than that, you could make an account on imgur or photobucket, upload the pictures there, then share them here via links, they should automatically embed and it'll look just like you uploaded them here.
Blckshdw
Moderator
How large are these images (file size and resolution)? I haven't tried .pngs, but .jpgs and .gifs should work without any issues as long as the file size and resolution are within decent limits.
- Aug 15, 2012
- 191
http://s358.photobucket.com/user/noneofurbz129/slideshow/
Hope this is good. It's driving me batty trying to figure out how to get these images up...
Crap!!! Sorry about the multi-post Mods...! Can you guys make it so that we can delete a post in case of slips like this?
Hope this is good. It's driving me batty trying to figure out how to get these images up...
Crap!!! Sorry about the multi-post Mods...! Can you guys make it so that we can delete a post in case of slips like this?
Blckshdw
Moderator
Your 2nd post was outside of the 10 minute window, so you're fine.
From your Photobucket page, there's a placeholder for a profile pic on the top right of the page. Hover the mouse over that, and you get a drop down menu. Choose Settings. From there click the Albums tab, and under links, make sure "IMG code" is checked.
Now from your album, below each pic in the album, or off to the right if viewing a single pic, there will be a text box with an IMG code in it. Copy and paste that code in your post here, and it will cause the pic to show up inline with your text.
This will allow you to post some text, with a pic below it, then more text about something else, and more pics for that. Something you're not able to do if you use the attachment method.
From your Photobucket page, there's a placeholder for a profile pic on the top right of the page. Hover the mouse over that, and you get a drop down menu. Choose Settings. From there click the Albums tab, and under links, make sure "IMG code" is checked.
Now from your album, below each pic in the album, or off to the right if viewing a single pic, there will be a text box with an IMG code in it. Copy and paste that code in your post here, and it will cause the pic to show up inline with your text.
This will allow you to post some text, with a pic below it, then more text about something else, and more pics for that. Something you're not able to do if you use the attachment method.
Robbabob
Member
- Dec 10, 2012
- 1,096
I only read the last two posts here, so I may have missed a deeper problem. Sorry if I did, but this may be helpful to others, too.
You can also press the MORE POST OPTIONS after you click in the text box (it is in the bottom right of the text window).
Click the Choose File, then click Attach This File.
When your photo attaches, you'll see an Add to Post to the right of your attachment. Be sure your cursor is where you want the picture to be in the post.
And you can keep putting words where you want.
Either way that works best for you.
Enjoy life, ccary on!
You can also press the MORE POST OPTIONS after you click in the text box (it is in the bottom right of the text window).
Click the Choose File, then click Attach This File.
When your photo attaches, you'll see an Add to Post to the right of your attachment. Be sure your cursor is where you want the picture to be in the post.
And you can keep putting words where you want.
Either way that works best for you.
Enjoy life, ccary on!
- Aug 15, 2012
- 191
- Aug 15, 2012
- 191
SUCCESS!!! 
Had to post these seperately. Error message said that i went over the allowed number of images...
Wanted to do the back pressure test and compression test today. But the truck isl at the body shop getting her makeup touched up. Wont be able to get to it until Sunday or Monday cause i have to work all day tomorrow...
Had to post these seperately. Error message said that i went over the allowed number of images...
Wanted to do the back pressure test and compression test today. But the truck isl at the body shop getting her makeup touched up. Wont be able to get to it until Sunday or Monday cause i have to work all day tomorrow...
if you got 320 out of a tank--was that all highway? and how many gallons did it take to fill it up? If you put in 22 gallons that's 14.5 mpg.....that's what my 2003 ext I6 gets around town......
Mooseman
Moderator
My MPG jumped when I changed the cat, which was partially plugged. Not enough to throw a code but just enough to choke it. I got a best calculated (not DIC) 21 MPG in my EXT, loaded with 4 adults and the back full of luggage and camping gear driving all highway with A/C on after I replaced it.
DocBrown
Member
- Dec 8, 2011
- 501
Trouble is if that's highway, that's not real good. That's what I was getting when my TB's CAT was clogged, like you I got 14 in town with a good CAT. When I was getting 6 mpg towing a 3500# travel trailer, that's what made me really start looking at the CAT. Normally towing that trailer I got 11.signalnc said:
He should be getting at least 19 highway, even with an EXT.
I'm in the camp that thinks this is a clogged CAT.
djthumper
Administrator
Tiggerr
Member
littleblazer
Member
- Jul 6, 2014
- 9,265
Just for comparison. I wasn't empty, all around town driving I got 13.54 mpg. So around 256 miles on about 18.9 gallons. BTW this is the best in town mpg I've ever gotten with the truck. It used to be hard to get 12.7.
Get the cat looked at.
Get the cat looked at.
BlazingTrails
Member
- Apr 27, 2014
- 19,409
It took me about 2 hours. You have to drop the exhaust mid pipe and just swap it out on the side of the transmission. YouTube has it
Mounce
Member
Shouldn't take more than an hour from what I've seen. Seems pretty easy. Google "putting Corvette servo in 4L60E"
- Aug 15, 2012
- 191
Update... Im still in SC (Myrtle Beach). Tried to get the back pressure test done but nobody seems to do it here. And cant find a tool rental. So, decided to Seafoam the truck. Sucked about 8oz into the brake booster hose, and guess what? No smoke! Thin puff for a few seconds, then nothing. Now, i opted not to do the oil and gas tank. But shouldn't there STILL be a significant amount of smoke???
littleblazer
Member
- Jul 6, 2014
- 9,265
Ziggy
Member
- Feb 8, 2015
- 207
I think you've reached the point of sucking it up and putting a catalytic converter on the truck. I'd suggest doing it sooner rather than later at this point, because now you've got Seafoam in the system. If it pulled 8 oz. in, and you got nothing to show for it, you should maybe get busy with the hack saw and cut the old cat out. Anyone know what the impact of Seafoam is on a catalytic converter?