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2008 GMC Envoy Denali

Time for some updates.....

First, the Viking double-adjustable rear shocks. When I installed them this fall, there was a definite ride improvement over the Belltech shocks I removed. However it still wasn't riding "good". I kept playing with the shocks a little here and a little there, trying to improve the ride. I would sometimes notice a little improvement, but not enough to not just call it the placebo effect. I always kept the settings in the lowest range since that is supposed to be the range that has the best ride quality. Finally one day while running errands I decided to ramp the settings up a couple clicks at each stop to see how that changed the ride thinking maybe the springs were too stiff and needed more control. After a couple stops I reached the end of the range in the compression, but could keep adjusting the rebound. Weird. As I remembered there were supposed to be something like 20 settings available for both compression and rebound and I thought I was a long ways from the top when I started. The next day I had the back of the truck up in the air inspecting the rear brakes and decided to run the shock adjusters through their range to make sure everything was ok. I backed the rebound on the left shock down and counted 18 clicks. The compression of the left shock I ran down and counted 10 clicks. Huh. So to verify I ran the rebound all the way up and again counted 18 clicks. I moved to the compression knob and after 10 clicks it stopped turning easily. I turned it through that and there was a pop. After that pop I was able to go all the way up to 18 with normal effort. I ran it down 18 clicks to zero and it was fine and then tried again up to 18 and it went through the range without a problem. Weird. I moved to the right shock and had the same exact experience. I decided to adjust both compression and rebound to 18 because I had never had the compression that high before and I wanted to see what it did. The next day I ran a 5 mile errand during my lunch hour and yep, it was riding rough. Before driving back to work I reached under and dropped all settings down to 0. I drove back to work and........it finally rides nice!! I was SO happy! It was really frustrating me that I couldn't get this thing to ride well. It's my preferred vehicle for us to take when we go places and the fact that it wasn't riding nice was making me resent the whole endeavor. I was ready to try a new set of springs thinking these lowering springs were just too stiff. No need now! But then I was concerned there was something wrong with the shocks. I called Tech Support at Viking and told them the experience. He thought it was weird the shocks had done that, but wasn't overly concerned. He wanted me to keep using them and didn't expect me to have future problems, but to keep an eye on it. It seems the shuttle valve springs were hung up for compression so I've been driving around with a higher compression setting since first installing them. If it starts riding rough again I'll know what's going on and contact Viking again. I'm so happy now!

This weekend I did another update that I've been putting off for a while - finally installing my improved cold air intake. Last year I was having trouble with the air filter getting soaked with water. I installed the air intake bypass valve to prevent me from sucking water up through the filter. I never did suck water in, but occasionally my filter would get soaked, like after getting a carwash, and if I gave it a bunch of throttle the engine would bog, even with the bypass valve. Not an ideal situation for sure and something I figured would get worse in the winter with slush and any water that would get on the filter freezing. I have had all of the components to install an improved intake, but haven't made the time to install them.....I finally made the time this past Saturday. This is what the "improved" intake consisted of: I bought a 4" diameter aluminum elbow with long legs and cut one of the legs short. Then I had an aluminum bung welded near the filter for an intake air temperature sender. After that I wrapped it with DEI Tunnel Shield and aluminum tape to help prevent the tube from getting heat soaked. I bought a new AFE air filter that was slightly smaller, but had a conical filter built into the end cap for extra air.

Here's the IAT sensor installed:

Intake 1.jpgIntake 2.jpg

Here is the new intake next to the old intake:

Intake 3.jpgIntake 4.jpg

And here is the final piece of the puzzle: a water-repellant Outerwears pre-filter. This should keep the water from getting onto/into the filter in the first place. It's a nice snug fit on the filter.

Intake 5.jpg

I installed it in place of the old piping and it fit in the old space the same though the radius of the pipe was slightly larger than the radius of the silicone elbow - the smaller air filter made sure it still fit.

Intake 6.jpgIntake 7.jpg

And I'm still sucking air through the fog light hole. I want to make a plug for the hole for the winter months so it will be less likely to get blasted with slush and snow, but that part still isn't done.

Intake 8.jpgIntake 9.jpg

This weekend I also did a couple other upgrades. I changed the defroster door actuator, the steering position sensor and the climate control module. I took pictures but after looking at them they wouldn't make any sense to anyone....needless to say, it was very tight under the dash and not much fun.
 
Glad you found the ride issue!

I understand why the filter is where it is, but just scares me. Sooo- snorkel! Nice cold air up high too and in the summer time actually colder air than next to the hot asphalt. Less dirt to ingest too.
I will admit not as smooth looking as the fog light hole, but your the guy to make cool things happen so I bet you could make a street snorkel look good!

full width 1/2” high “hood scoop” at the cowl?
 
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I understand why the filter is where it is, but just scares me. Sooo- snorkel! Nice cold air up high too and in the summer time actually colder air than next to the hot asphalt. Less dirt to ingest too.
I will admit not as smooth looking as the fog light hole, but your the guy to make cool things happen so I bet you could make a street snorkel look good!

full width 1/2” high “hood scoop” at the cowl?

I agree with you that the low intake is a bit scary. I'm still not a 100% fan, but it's the best compromise at the moment. I like the idea of a cowl intake, but I'm afraid of the extra noise inside the cabin - I noticed an inside noise reduction when I changed from the factory intake location to the fenderwell intake. As I was reading your comment I too did think about a low scoop at the cowl....maybe if it was a scoop rather than just a tube into the cowl it would be quieter? Also, when doing the installation this weekend I noticed that there is a lot of room between the grill and the cooling stack - maybe I can make some kind of a tube that sucks are from behind the grill into a box. Or maybe I'll just drive it into a pond, hydrolock the engine and cut my losses.....I'm honestly getting tired of working on this thing.
 
Whoa! starting to get burned out on a project means time to just drive and enjoy- which should be easier now that the ride is smooth!
I think maybe that is the skid steer or Tahoe I hear calling? Haha

The snorkel was a joke, but I am old school fan of a hood scoop as my hummer attests. Mine is just for the radiator instead. But the aerodynamic look of that ride- just cant picture a single side scoop looking right.

yes the full width at rear of hood would work, but would increase the noise and drag.
maybe naca ducts on each side of the hood like the Ferrari F40? A 3” on each side would have more than enough to feed an airbox and keep the noise away at the front of the hood.
 
Or a pair of scoop ducts (or just one atop the passenger fender) curved to match the contour and about 2" high at the high point and about 5" wide overall, one on top of each fender, up front near the grille so they can catch the airflow and ducted to an airbox containing your new filter/intake. Or your idea of capturing the air higher and in front of the cooling stack and ducting it over to the new filter/intake.

But you're right, Nate. Enough on this vehicle. I hear that skid steer calling your name, Spring retaining wall season is just around the corner!
 
Whoa! starting to get burned out on a project means time to just drive and enjoy- which should be easier now that the ride is smooth!
I think maybe that is the skid steer or Tahoe I hear calling? Haha


I have mixed feelings about this ride. It's fairly comfy (especially now that I have the shocks working correctly), gets looks when people hear it idle and is pretty fun to drive. But on the downside, it's not any quicker than the Tahoe (I have yet to get it to the strip to verify) despite being 1000 pounds lighter, it gets worse fuel mileage (again, despite being lighter and more aerodynamic) and it can't tow as much. And for the money and time invested I feel like it should be faster, though to be fair, I built it with the idea of running 87 octane, so that surely has cost me some power. To be happier with it I'd have to add a turbo, which would require re-gapping the rings, maybe swapping the cam.....actually I should say that I WOULD/SHOULD swap the cam because I'd want something that would optimize the turbo giving me more power AND hopefully better fuel economy, a 4L80e and then probably change the gears AGAIN back to either the original 3.42 ratio or maybe 3.73. That's a lot of work and money into a vehicle that ISN'T EVEN SUPPOSED TO BE A PROJECT! I need to just finish the last couple nit-picky things and then drive it and be satisfied....just not sure I can ever be satisfied. I know.....boo-freakin-hoo. Maybe I need to find a nice Suburban with a 6.5 instead. Though one of the things about the Envoy that's a huge plus is the dual-zone climate control. My girlfriend is always warm, I'm always cold, this is the first vehicle we've had that we can both be reasonably comfortable in. So a GMT400 would be a step down in that regard. My next best option would be a 2003+ GMT800 SUV with a 6.5 swap....which may happen one day, but I for sure don't need THAT project right now!

You guys are all forgetting the next project - the 94 K3500. That's getting worked on first. Then the skidsteer, THEN the Tahoe. That is until I find another project to work on and then all bets are off. I just need to spend a little more time in the barn getting it cleaned up and organized and then the K3500 is getting pulled in and torn down.
 
Quick follow-up on a couple things:

1. I got a car wash the other day. When I left the wash I floored it up to 55mph and it didn't bog at all. This tells me that the Outerwear is doing its job and keeping the water out of the air filter. I was also looking at alternative routing ideas for a more permanent solution.....I think there are things I can do with a bunch more fab work, but I'm not sure I want to invest the time and money in this one...….I have 6.5 projects to work on!

2. The climate control module I installed was a new (not remanufactured) one from Dorman. After reading reviews on the remanufactured ones failing not long after installation it seemed best to just spend the extra money and get a brand new one. Brand new from GM is discontinued and the NOS ones you can find are over $500.....that didn't seem like a viable option. Anyway, I installed the module Sunday, but didn't really use it that day other than to make sure all the functions were working. By the way - the only reason I was changing my module was because some of the bulbs were burnt out in the factory one and they're LEDs soldered to the board. So Monday I'm driving around and I notice 2 peculiar functionalities: First, the display never showed the outside temperature when the module was in idle mode. The factory module would revert to the outside temperature after you changed a temp or mode setting. If I turned the power off the Dorman unit showed the outside temperature, so it was getting a reading from the sensor, it just wasn't displaying it. Second, when I selected "Auto" mode, it would always turn the air conditioning on. This is weird. It was 15 degrees outside Monday morning and its default in Auto mode was to turn the A/C on! Dumb. There's a calibration procedure that you do when you first install the unit because it can be used in multiple GM vehicles. I had done the calibration Sunday, but decided to try it again Monday just to be sure. I went through the procedure and it still behaved the same. So I emailed Dorman tech support. I actually got a response from them pretty quickly. They said that those are known issues with the programming and there wasn't anything to be done about it. They told me I could return it for a refund and suggested that if I got one of the reman units it would have the GM software in it. After I told them I had read bad reviews on the reman unit they said I could have a refund. So I uninstalled the Dorman unit and reinstalled the factory one. I searched on eBay for another factory module and found a place in Wisconsin that refurbishes factory units. It was a little pricier than the new Dorman unit, but if it functions as OEM and everything works on it (including all bulbs) and lasts me, then it's money well spent. I received the package yesterday, but I haven't even opened it yet. I will install it soon and report back on the unit.
 
Would it be possible to take apart Your original unit and then unsolder the bulbs and replace them ?
Just be sure to install them the right direction or else they wont work.
Yes, it definitely is possible, in fact the same place that I bought the refurbished unit from sells the LEDs to do that. I'm just at a point where the extra labor to do that doesn't make sense to me. I am definitely going to keep my existing unit and then may give replacing the bulbs a go in the future, but right now that labor is better spent on other projects.
 
Had some fun with the Envoy tonight. Joined in a little mini parade to help one of the kids in the family celebrate his 11th birthday! It was a lot of fun and I think he enjoyed himself. It should be a great memory for him for years to come. Oh and sorry about the crappy quality, I couldn’t download the video so I had to record my screen 😅

 
I picked up another set of wheels last night so I can have my summer and winter tires premounted for easy swapping. I’ve been eyeballing the 18” Trailblazer LTZ wheels for a while because I liked that they had a nice 5 spoke design rather than most wheels for this platform have a symmetrical spoke design. I found a nice looking set locally for a good price so I bought them. I just installed them (with the tires that came on them) so I could see how they looked. I honestly thought it would be a more significant change than it is. I think what would make them look best is to plasti-dip them black and also do the chrome grill - that would match the rest of the black trim and tinted windows. In fact the GMC wheels could probably benefit from that as well.

Envoy Denali 18” wheels
ABC977E6-CF20-4944-AD0C-7E978E220121.jpeg

Trailblazer LTZ 18” wheels
14D641A5-065A-4362-8210-FCFAA6779B3F.jpeg
 
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