Kids, don't leave home without your code reader!

Reprise

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Just got back from my scouting trip for next April's eclipse (yes, I found some promising spots / campgrounds).

Had some tools with me (mandatory for RV owners), but no code readers / dongles. To be honest, I trust the Sierra as a reliable vehicle, so I didn't even think about a code reader (it's never really thrown one, while I've had it)

Driving along a state route to connect me to another interstate, I ran into some sort of police action where they closed / blocked off the road, and made everyone detour. So a long line of us were driving at about 15-20mph through housing developments and cornfields (cue 'conga line' or 'baby elephant walk'). At that point, I saw another yellow lamp across the dash from the 'tow / haul' light -- the 'check engine' light.

"Oh NOES!!!111!!!111 She's gonna die, and I'll be stranded!"
As I saw the gages move nary a tick from their usual 'optimal' readings, I thought... "well, it can't be that bad... lubrication and cooling are fine, and so is engine power". So I decided to 'chance it' and drive the 100mi remaining to my next destination.

When I got there, I dropped the trailer, leaving the truck running as a safeguard, and headed for the nearest AutoZone, which was just a few miles away.

Sure enough, when they hooked their reader up, it reported a rear O2 sensor low voltage condition. Pffft! Nothing to worry about... and if I'd bothered to bring along a dongle, I could have saved myself a lot of stress and worry.

But that's how much I've come to trust the Sierra (granted, it has a LOT of replacement parts that I've put in it over the time I've had it, just getting it caught up on maintenance, etc., along with the cam / valvetrain upgrades I've put in). As an aside, the CEL turned itself off the next day (but came on again, after I'd been driving for a couple of hours).

On the bright(er) side, having now towed the trailer about 900 miles round trip across the plains of Illinois, which only gets slightly hilly in the south end of the state... I was rather pleased with both how the Sierra handled 5800lb in tow, and how GM engineered 'tow / haul' programming, at least in my truck's generation. With the exception of one thing -- 50-65 mph is apparently a 'no man's land' WRT getting the converter to lock up, while you're bringing the truck up to speed. So you have to endure that range with the engine revving about 500rpm more than it needs to. Once you get it to lockup in 4th, it'll sit all day on flat terrain at about 2000-2100 rpm, driving with load (at 65mph, which is the rated limit on our roads and for my trailer tires). Cruise control is useless; too much downshifting. 70mph will turn about 2200-2300 with my 4.10; 55mph will sit at about 1800rpm. Not bad for a 12,000 lb. rig and 4.10 gear! Basically, tow / haul mode will run about 200rpm higher at cruise, vs. not using it / not towing. It does hold shifts longer, of course.

Best part of all? I measured my first tank at almost 10.2 mpg (and the DIC reported almost 10mpg for the entire trip).
Most of you will probably say... "you're pleased at 'almost 10mpg?'
Well, compared to the expected 8mpg... that's almost a 20% improvement! And it convinces me to stop looking for the 'right' Duramax as a next truck, at least from a MPG perspective. :celebrate:
 

Mooseman

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Dec 4, 2011
25,646
Ottawa, ON
Hell, I have a code reader in my 2021 Sierra! It threw a code for an ambient air temp sensor but, before I could get it in to the dealer, it went out and hasn't come back on. Since it's a new diesel engine with a DPF, I want to stay on top of anything that could happen. I have to say that so far at 43k km, except for this glitch, it's been flawless. My only minor gripe is the pitiful excuse for engine braking while towing. It's practically non-existent and a common complaint among owners. But with my stellar fuel efficiency, I can't complain. On my last 1900km trip (no trailer), it averaged almost 27MPG. While towing our 7000# trailer, I was averaging around 12MPG, which ain't bad. And with diesel prices back under the price of gas, it's another win.

Now I have to replace all the brakes on the trailer. One drum got the magnet surface deeply grooved and the magnets are all worn. Luckily my DIL works in a truck parts supply store and got me a sweet deals on parts. A drum that is normally $150 she got for $54 and self adjusting brake sets for $50 each instead of a no-name on Amazon for $75. Time is however tight to do it.
 

Reprise

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On my last 1900km trip (no trailer), it averaged almost 27MPG. While towing our 7000# trailer, I was averaging around 12MPG, which ain't bad.
Damn, that's a big delta! I know better than to ask about VCM, because I know you'd defeat it rather than run it. But did you miscalculate the liters > gallons on the unloaded half?

Since I'm in the 14-15mpg range unloaded, 30% decrease under load seems 'acceptable' to me, and +20% potential over what the Envoy did justifies the expense and effort (I have :tiphat: to you many times for suggesting to focus on torque; along with what the HD full-size pickup platform provides, it's just a much more relaxing experience when towing).

I need to duplicate my trip to Montana to compare what towing at elevation is like with my Sierra, but I'm starting to think what it's 'got' (in terms of HP / TQ) might be 'enough', vs. my current plans.

One of these days, when the whole of Canada stops burning and you have time to burn (pun intended), we'll have to get together with our respective trailers and have a 'pull-off' (not so much 'competition', as 'comparison').

PM will be coming your way in a day or two (you've been warned! LOL)
 
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Mooseman

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Dec 4, 2011
25,646
Ottawa, ON
Damn, that's a big delta! I know better than to ask about VCM, because I know you'd defeat it rather than run it. But did you miscalculate the liters > gallons on the unloaded half?
The road to North Bay, HWY 17, is very hilly so that's where my MPG is going. I'm sure if I was towing in Saskatchewan, it would probably be closer to 20 MPG. And it never goes into active regen. From what I understand, it has a passive regen where it will continuously regenerate since it's working harder and creating elevated exhaust temps. In fact, I can see that the soot load would go down while towing and DEF a little at a time. It does use more DEF while towing.

I'm still lovin' it :love0001:
 
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6716

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Jul 24, 2012
830
Since the CEL in my Trailblazer is basically never off, I keep a code reader in the center console and check the codes every so often to make sure it's only the codes I already know about.
 

pell

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Jun 5, 2017
88
Pelham, NH
Some people read their horoscope's, I have "The code of the day", which is usually nothing. They do seem more frequent around inspection time, ever had it light up on the way to the inspection station.
 
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Reprise

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Jul 22, 2015
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Sorry for the hijack reprise

Oh, ok... if you must... ::huffs:: :laugh:

(as an aside, diesel looks to have reached parity (within .01-.02 either way) with unleaded 87, here in metro Chicago)
 

Mooseman

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Dec 4, 2011
25,646
Ottawa, ON
Here, in the morning, diesel is cheaper by about 6-8 cents per litre but by evening, they're almost even. Gas fluctuates wildly here but diesel is steady unlesst here is an actual price change.
 
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