What did you do to your NNBS GMT900 Tahoe/Yukon Today?

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lowh07

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Tucked away for the hurricane, but turns out it shouldn’t be too bad here. Hope everyone in south LA finds higher ground...

8D45E9AD-625C-46C5-8F6C-BD07E44CC071.jpeg
 
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the_tool_man

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Good. Clean the MAF and TB and go from there.
Mine has started stumbling at idle immediately after cold cranking. It hunts back and forth a bit and then settles down. I cleaned the MAF six months ago. I'm going to clean the TB and see if that helps. I suspect it's got some gunk in it.

I didn't see an answer to Kee Fuller's question...remove the TB to clean or not?

Related question, assuming this may be causing the idle issue. How hard is it to replace the O2 sensors? When I got my BB tune, 17k miles ago, the tuner said they were getting a bit lazy, and recommended I replace them (front ones only, rear are disabled).
 

iamdub

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Mine has started stumbling at idle immediately after cold cranking. It hunts back and forth a bit and then settles down. I cleaned the MAF six months ago. I'm going to clean the TB and see if that helps. I suspect it's got some gunk in it.

I didn't see an answer to Kee Fuller's question...remove the TB to clean or not?

Related question, assuming this may be causing the idle issue. How hard is it to replace the O2 sensors? When I got my BB tune, 17k miles ago, the tuner said they were getting a bit lazy, and recommended I replace them (front ones only, rear are disabled).

Missed that detail. I'd remove it since it's so easy to and to get a much more thorough cleaning. It'd also keep the gunk you're cleaning off from getting into the manifold where it would be sucked into the engine. If there's a film of gunk on the surface and you don't completely remove all of it, the cleaning chemicals could soften it so that it flows down and collects against the throttle blade where it will re-solidify and act as adhesive, making the blade stick.

Lazy O2 sensors can cause inaccurate fueling, which can certainly affect idle quality, drivability, reduced power, MPG, etc. The biggest pain with replacing them is unscrewing them. For one, they're kinda in a tight spot so getting the car up as high as possible on jack stands makes it easier. The bigger problem is that they've been known to be so tight (seized?) that people have had to replace the Y-pipe just to replace the sensors or at least remove it to break and drill them off. I'm sure this mostly depends on the rust factor in your area. Mine were tight, but backed out by hand after cracking them loose with crescent wrench. Rust doesn't exist here, though.

I highly recommend Denso O2 sensors.
 

cmatt

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I need to change the brakes on my wife’s 2017 Acadia and saw where it’s now recommended to change the rotors out as well instead of having them resurfaced. Something about they’re made with such tight tolerances now they don’t have the material to remove.

Is there validity to this?


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PG01

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I need to change the brakes on my wife’s 2017 Acadia and saw where it’s now recommended to change the rotors out as well instead of having them resurfaced. Something about they’re made with such tight tolerances now they don’t have the material to remove.

Is there validity to this?


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Nah, just the cheap price of new rotors nowadays.... plus not as many shops resurface any more as the rotors are so cheap.
 

the_tool_man

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I need to change the brakes on my wife’s 2017 Acadia and saw where it’s now recommended to change the rotors out as well instead of having them resurfaced. Something about they’re made with such tight tolerances now they don’t have the material to remove.

Is there validity to this?


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If they're just glazed, you can go over them with a random orbit sander to give them a uniform bedding surface for the new pads. If they're grooved, it's about the same to replace them as to get them turned, assuming you can find a shop that will even do it. The minimum rotor thickness should be cast into them, or otherwise marked near the hub area, or on the outer edge.
 

Monz11

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Engine almost completed. Just have to install thermostat housing, steam line kit, and Maggy.
My brother started cutting the rear bump stops, while I finished this beauty Sunday. I should get the tranny back, after vacation in a few weeks.

Order maggy, vibrant silicone hoses, braided E85 fuel lines, and black braided tranny lines.

Ac bracket.jpg Alt ps.jpg Eng ac bracket.jpg
 

Drok

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So i know im way late on this, been busy at work. I forget who was talking about reverse leds but these are what i have and they’re fantastic. Got them from superbrightleds.com. I also have them in the other two spots in the taillight but in red led

apparently my truck is on its side, Idk why the pic is that way. Haha

330D621F-1E7E-4384-82AD-9E04F73DDB62.jpeg
 

iamdub

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I need to change the brakes on my wife’s 2017 Acadia and saw where it’s now recommended to change the rotors out as well instead of having them resurfaced. Something about they’re made with such tight tolerances now they don’t have the material to remove.

Is there validity to this?


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That's what I was told last I went to O'reilly's to have mine resurfaced. Their lathe was down and they said corporate wasn't so concerned with fixing it because rotors now are designed to be "one time use and disposable". It's not tight tolerances, it's thinner rotors that are pretty much already at their minimum thickness when new. I took my "old school" rotors across the street to the mechanic shop and they turned them for $8 each. I measured them before and after and they were a hair over the minimum thickness after resurfacing.
 

Doubeleive

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Mine has started stumbling at idle immediately after cold cranking. It hunts back and forth a bit and then settles down. I cleaned the MAF six months ago. I'm going to clean the TB and see if that helps. I suspect it's got some gunk in it.

I didn't see an answer to Kee Fuller's question...remove the TB to clean or not?

Related question, assuming this may be causing the idle issue. How hard is it to replace the O2 sensors? When I got my BB tune, 17k miles ago, the tuner said they were getting a bit lazy, and recommended I replace them (front ones only, rear are disabled).
front drivers side is a bit of a ***** to get to because the space is tight, I had to use both a 02 socket and a offset socket to get it in tight, getting it out shouldn't be that hard because you just need to break it loose.
 

iamdub

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Spent about 4 hours under it trying to figure out how I'm gonna do my crazy ass exhaust. Well, about 2 hours of that time was working on the valve.

Made cardboard templates of each of the mufflers to figure out orientation. The smaller one I'm currently running is a centered/offset configuration, the long one I'll be adding is centered/centered. Was trying to determine which one should go first and how it and the valve will be positioned. It looks like it's gonna come down to me modifying the cross member for the extra space.

IMG_2868.JPG



Yes, I'm still working on that damned mower... Sometimes.


IMG_2870.JPG




So far, I'm thinking this is a winner. Put the bigger one first and angle it and the valve as pictured so that I can tuck it up as high as possible with nothing extending below the frame rails with about 1/2" to spare. The second muffler will be clocked the same. The 3" straight pipe will run parallel. It will be on the ground/far side of the system so the mufflers will act as a sound barrier between it and the floor of the cabin. They will merge together right at the arch that goes over the axle.

I also tested out the DPDT rocker switch on the valve. I'll do all the wiring at the switch so I'll only have to run two wires to the switch (12V+ and ground) and then two wires (+ and -) from the switch down to the valve to have bi-directional control.
 

992dr

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Sam, Gruvenparts makes billet T hose connectors, and you can also pick up Vibrant Silicone hoses, that will never go out.

I have seen that, that fitting is not cracked (yet) this was only to replace the Y down by the thermostat housing.

screw that get Vibrant silicone hoses and rehose the entire engine!

Since it's my daily and only means of transportation I had to button it up quickly. That is my plan and will definitely be a project for a later date.

Spent about 4 hours under it trying to figure out how I'm gonna do my crazy ass exhaust. Well, about 2 hours of that time was working on the valve.

Made cardboard templates of each of the mufflers to figure out orientation. The smaller one I'm currently running is a centered/offset configuration, the long one I'll be adding is centered/centered. Was trying to determine which one should go first and how it and the valve will be positioned. It looks like it's gonna come down to me modifying the cross member for the extra space.

View attachment 255848


Yes, I'm still working on that damned mower... Sometimes.


View attachment 255849



So far, I'm thinking this is a winner. Put the bigger one first and angle it and the valve as pictured so that I can tuck it up as high as possible with nothing extending below the frame rails with about 1/2" to spare. The second muffler will be clocked the same. The 3" straight pipe will run parallel. It will be on the ground/far side of the system so the mufflers will act as a sound barrier between it and the floor of the cabin. They will merge together right at the arch that goes over the axle.

I also tested out the DPDT rocker switch on the valve. I'll do all the wiring at the switch so I'll only have to run two wires to the switch (12V+ and ground) and then two wires (+ and -) from the switch down to the valve to have bi-directional control.

Interested in this crazy ass exhaust. Will you be running two mufflers and a straight pipe with the valve? I'm trying to picture it but am too tired haha. Doodle it up
 

PG01

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I have seen that, that fitting is not cracked (yet) this was only to replace the Y down by the thermostat housing

Since it's my daily and only means of transportation I had to button it up quickly. That is my plan and will definitely be a project for a later date.



Interested in this crazy ass exhaust. Will you be running two mufflers and a straight pipe with the valve? I'm trying to picture it but am too tired haha. Doodle it up


There goes Sam, nicest guy on here....:) you just seem like a genuine nice guy.
 

MLRTYME

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Nice. You should do a build thread.

Sorry, just getting back to this. I'd suck at a build thread as I don't stop to take pictures...ever. Unless it's an engine that I'm gonna play with on the flowbench or dyno or put in a fun car, I consider it simply a mode of transportation. Basics are as follows: Crank/rods stock but light polish on the crank and resized the rods for ARPs. Weisco pistons/rings (.50 over). Heads worked to flow 22cfm more at 600 intake and 15 cfm more at 600 ex. Stock cam, new LS7 lifters, BTR pushrods, comp trunion kit, mellings pump and everything else is just GM stuff. Nothing special. No power adder. No juice. No full roller T&D Rockers. Just the time taken to make sure all the little things (front/rear mains centered, oil pan flush with back of block, oil pump centered...etc) are done right. I need another 130k out of this! :)
 

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