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2007 gmc envoy_denali
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Please stop arguing over the flush guys, its not helpful here :(
I'm sorry GG, I just hate it when folks repeat bad info and try and scare you into neglecting your vehicle. There are a lot of folks with high mileage rigs who would benefit from a flush, but are too scared because of what's been going around since before the internet. My personal experience spans 4 full flushes, 2 of which were 4L60 rigs, and none of them died. Filter changes on my 1500 would NOT get the fluid clean. That's worth exactly what you paid for it. I have heard the machine is the one that tends to kill them as it has a rather high operating pressure, and I have heard if your transmission is acting funny and you try a flush as a hail Mary it's probably going to kill it, but if you have a healthy trans and flush the way I laid out with the transmission's internal pump by simply removing the return line, myself and others have had real world good experiences and nobody here can take that away. Once you're past that hurdle, you can continue to flush on schedule and get the longest possible life from your transmission. For the time being, this likely plugged cat and VVT issue should take precedence. Best of luck!
 

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2004 chevy trailblazer_lt
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Supercharged111, I think the real confusion is in how people define/interpret the term "transmission flush". To many of us, a transmission flush is a process where a service facility connects a pressurized machine to the transmission system and it forces out the old fluid, sometimes sends through a "cleaning solution" and then puts in X number of quarts of new transmission fluid.

In my opinion, what you are referring to is more of a "clean version of the ole' spill and fill ATF fluid and filter change' maintenance procedure. I myself have used this procedure to pump 3 - 5 quarts of transmission fluid out of the transmission because the transmission pan did not have a drain plugs, and I was simply replacing however much AT fluid I got out with new AT fluid. Yes, your method gets more old fluid out at one time, but because I do not wait until 30,000 to 50,000 miles before I do my initial AT fluid spill and fill, I am primarily replenishing and fortifying the AT fluid's additive package.

I do this every 10,000 to 15,000 miles.to ensure my fluid does not get burned AND to ensure that I do not drastically change the chemistry of the transmission fluid. This way the varnish that has formed on the clutch material is not stripped away and it stays where it needs to be.

Now, I have never heard of a transmission in good shape failing your method or my method, I have heard of people who do have existing transmission problems who get a spill and fill transmission service performed, seeing a transmission failure shortly after the spill and fill maintenance. In all likelihood, their transmission would have failed without the maintenance.

Now, Ravalli Surfer was in the transmission repair business for a lot of years and has a great deal of valuable experience that he is generously willing to share with all who frequent the forum. Hence, he prefers to refer to maintenance or repair procedures by their industry standard names. Hence, when he "hears" someone refer to a transmission flush, he automatically thinks of the procedure involving the expensive, pressurized transmission flushing machine that many service providers use to fleece customers.

Now, with that kind of a transmission flush there is a very real chance that a transmission that has been poorly maintained over the miles and the years, and is subjected to a flushing procedure which literally shocks the automatic transmission system, will have a catastrophic failure within a very short period of time. He made a lot of money repairing/rebuilding transmissions that failed because a service provider was more interested in getting another $100 - $200 out of a customer.

So, I guess in closing I would say "...now you know the inside story..."

Regards!
 
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Discussion Starter · #64 ·
So I officially know what the issue is thanks to removing the updraft O2 sensor... the cat is completely clogged so it will need to get replaced... as soon as I removed it, I was able to do 0-75 in about 12 seconds as to where before it would take 45-65 seconds... and as soon as the O2 sensor was put back in, it bogged down haaaaaaaaaard
 

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So I officially know what the issue is thanks to removing the updraft O2 sensor... the cat is completely clogged so it will need to get replaced... as soon as I removed it, I was able to do 0-75 in about 12 seconds as to where before it would take 45-65 seconds... and as soon as the O2 sensor was put back in, it bogged down haaaaaaaaaard
So once that VVT code is all cleared up, any chance it's clean itself? Is there some sort of miracle juice you can pour into an almost empty tank to get it cleaned? Was the VVT stuff the cause of the clogged cat? Wouldn't want that problem coming back.
 

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Discussion Starter · #66 ·
So once that VVT code is all cleared up, any chance it's clean itself? Is there some sort of miracle juice you can pour into an almost empty tank to get it cleaned? Was the VVT stuff the cause of the clogged cat? Wouldn't want that problem coming back.
My best guess is it was just the carbon buildup after 212.3k miles... I could technically put CataClean in the tank when I have low af gas in the tank but Im just gonna replace it since its bolted in on both ends, no welding required... Also just gonna replace the upstream and downstream O2 sensors while im at it so on the 27th everything will be here from RockAuto and she'll be good to go again! Also the VVT code and the misfire in cyl 3 is already gone, it was just the cata P0420 code at this point
 

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2003 chevy trailblazer_ltz
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Superchrged111 is the ONLY person on these forums who advocates a full trans. flush. The ONLY one.
Take that as you will.
You forgot about me. I already had my long, drawn-out argument with him over trans flushes and the logic thereof.

So once that VVT code is all cleared up, any chance it's clean itself? Is there some sort of miracle juice you can pour into an almost empty tank to get it cleaned?
Once a cat is plugged, it'll never get hot enough to burn out the accumulated carbon. The engine will run so poorly that it will just get worse until the vehicle won't run at all.

I had the OEM cat on my '03 plug to the point that the vehicle would barely move--2--3 mph. I went from "Perfectly Normal" to crawling in the space of maybe forty miles, on I-90 in the middle of South Dakota. (The MIL light had been on for hundreds of miles; but I had no tools with me. Tried to get home...failed.) Had the cat replaced with a "universal" cut-and-weld job.

That plugged OEM catalyst went to my friend the automotive machinist. He's got a parts-cleaning oven; heats greasy engine blocks and such to the point where the grease and oily dirt turn to ash. He baked my catalyst as an experiment. It seems to have worked--I can see through it again--but it's never been reinstalled on a vehicle.

As further advice on Trailblazer 4.2 six-poppers and O2 sensors...O2 sensor sockets are really pathetic at REMOVING seized O2 sensors. They do a great job of installing them. The split down the side makes them weak--you apply enough torque and they just spread open and slip. This damages the hex, if it's bad enough no wrench will work. But all that is OK, because the exhaust manifold is probably cracked anyway. Therefore, the better solution is to NOT **** with the sensor itself, but to replace the entire manifold and heat shield, with a new O2 sensor in the new manifold.

Automotive tire Wood Grey Trunk Tread


The hole in the manifold is for the O2 sensor. Note the huge crack right next to the O2 sensor hole.
Tire Automotive tire Wood Art Rim


Botany Bicycle part Grass Plant Terrestrial plant

The heat shield covers the entire manifold; it's hard to see if it's cracked or not--but maybe you hear exhaust leaks around the manifold, or maybe you can see cracks around the O2 sensor bung through the hole in the heat shield that the sensor pokes through.

If that's just not practical, buy a Wright deepwell impact socket. No split down the side, and unlike most other impact sockets, there's enough room inside for the body of the O2 sensor after you cut the wire harness. Even if you don't have an impact wrench, this is the socket to use with a quality ratchet or breaker-bar and a long cheater-pipe.

Wright is a family-owned USA tool company; it's good stuff at half or less the price of Snap-On (and the Snap-On socket doesn't fit over the O2 sensor body.)
 

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2004 chevy trailblazer_lt
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GreaseGirl95, thanks for letting us know what you found! A couple of recommendations regarding the parts you intend on purchasing. Get a California rated catalytic converter - they will last the longest of all the aftermarket ones and will cause the least amount of headaches going forward. This advice comes from several professional mechanics on the Bob is The Oil Guy forum (/bobistheoilguy.com) that I also subscribe to.

Secondly, purchase either Denso or ACDelco Oxygen sensors. Bosch ones create more headaches than the ones they solve.

Again, thanks for the update and good luck!
 

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2004 chevy trailblazer_lt
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GreaseGirl95 I forgot one thing. Since you are going to be moving to New England after your husband's discharge, emissions inspections and rules are much tighter there. Hence, another good reason to spend the extra $$ for a California certified cat con. Some of the New England states also require the use of CARB certified/register cat convertors as well.
 

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Discussion Starter · #70 ·
GreaseGirl95 I forgot one thing. Since you are going to be moving to New England after your husband's discharge, emissions inspections and rules are much tighter there. Hence, another good reason to spend the extra $$ for a California certified cat con. Some of the New England states also require the use of CARB certified/register cat convertors as well.
Way ahead of you there ^-^ Got a Cali Cert that is CARB Cert as well, as for the O2 sensors, I think I ordered Denso... It was that or ACDelco
 

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2004 chevy trailblazer_lt
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Way to go!!!! You did good!
 

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TrailBlazers with the 4.2L I6 engine only has two Oxygen sensors. One upstream sensor (B1S1) and one downstream (B1S2).
 

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I know the feeling all to well. Hang in there! We are rooting for you!
 

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Discussion Starter · #76 ·
OH SWEET JOLLY FREAKING RANCHERS ITS NOT GONNA BE HERE TILL SUNDAY NOW... Maybe if they hadn't let it sit in freaking New Jersey for 26 hours it would have been here on time... or you know, take 9.5 hours to do a 3 hour trip... Not sure how thats even freaking possible but what ever... god I hate fedex
 

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Yes,I have been seeing many reports of poor FedEx service the last few months.
 

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If it hung around NJ too long, it may be an empty box by now.

Motor vehicle Window Pollution Mode of transport Wood
 

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Discussion Starter · #79 ·
K so finally after 13 hours of hell with my friend helping, we finally got the new cat in... driving sooo much better but still getting a couple codes... Gonna clear them via unhooking the bat and seeing what pops up after a couple days of driving around but at least she doesnt bog anymore... In case anyone was wondering, the codes that came up were P0442 (EVAP system small leak detected)... probably from me not tightening down something all the way even though it was as tight as I could get it... Other code was P0172 (System Too Rich Bank 1)
 

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Gonna clear them via unhooking the bat
That hasn't cleared codes since at least '96 model year. You'll need a scan tool or code-reader to clear the codes.

In case anyone was wondering, the codes that came up were P0442 (EVAP system small leak detected)... probably from me not tightening down something all the way even though it was as tight as I could get it... Other code was P0172 (System Too Rich Bank 1)
Evap system is often a failed (or loose) gas cap. Can be lots of other stuff, but often the cap.

How old are the O2 sensors?
 
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