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03 Trailblazer 4.2 Sluggish Acceleration

5627 Views 106 Replies 15 Participants Last post by  Trailnut
Hello! New here... Just got an 03 Trailblazer 4.2 with 212k miles on it with some sluggish acceleration. I need to replace the VVT solenoid (have it being delivered tomorrow) but I am not sure if that will still fix the issue. If I do replace the solenoid and its still sluggish, what are other issues that can cause this issue? Ive seen reports of like a clogged Cat Conv but I think it may be transmission related (such as the torque converter) because it has a hard time with hills and then also it has an issue changing gears... Any suggestions would be appreciated!!!
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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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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?
A dongle plus your smart-phone. The web-site is the text equivalent of a late-night TV infomercial. Very shady. Wildly overpriced.

They're big on telling you it does what you need...without ever telling you what it actually does. Apparently, it's a cheap consumer-grade code reader.

I love the "fine print' at the bottom of the page:
HEALTH DISCLAIMER: This website is not intended to provide medical advice or to take the place of medical advice and treatment from your personal physician. Visitors are advised to consult their own doctors or other qualified health professional regarding the treatment of medical conditions.
Now splurge and get yourself an inexpensive, yet capable OBDII code reader/live data scanner.
Hey it works for me and tells me the codes so I dont really care xD
The point is, "codes" are NOT ENOUGH, and why I'm so peeved at crooks that take advantage of people by advertising code-reader junk as if it were The Ultimate Solution to whatever problem the vehicle has.

Having access to the data stream--"Live Data"--and some bi-directional control is more useful than "codes" at least half the time, and maybe more. "Codes" are often helpful, live data is ESSENTIAL.

For regular daily driving I should just be in 2WD yeah?

Cruise control should be on the turn signal lever. A slider-switch for Off--On--Resume/Accelerate; and a button on the end to Engage or to slow down.

The "roadway" on the pushbutton on the steering wheel is likely for the Driver Information Center (DIC) in the instrument cluster, and not all vehicles have that. Those that do, can display the odometer reading, trip odometer, trip timer, estimated instant or average fuel economy (MPG), mileage until the gas tank is empty, (range to empty) and some other info.

I can't help with the TC button. Mine doesn't have that. However, there's no reason to turn it off in normal driving. You might have to turn it off in special circumstances.

May I suggest buying or downloading a copy of the Owner's Manual?

.............I have left the building .......

View attachment 58902
I bet most folks have absolutely no idea what that image is.

But we old codgers remember TV test patterns. That, and the National Anthem being played when the station went off-the-air at midnight or 1 am.
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Interesting that they make no mention of live data; or show any sensor data on the web page.
4wd it has a terrible bind when turned sharply.
Of course. The transfer case isn't allowing for the difference in turning radius between front and rear wheels.

TOTALLY normal.

Some "AWD" transfer cases have a viscous coupling that allows it to act as a front/rear differential...but that limits how much torque can be directed to the front unless there's some method to lock it up like a 4WD.
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