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By Leslie Politron
Hi. I bought a new 2021 AT4 March 5. 20 miles on it. Drove home from the dealer (4 miles) and the next time I turned it on, CEL and OnStar diagnostics emails me to take it to the service department. They say they reset MAP sensor and send me on my way. Later that day, same thing happens. I take it back in, they say MAP sensory needs replacing. They had it almost 2 weeks waiting on the part. After they replaced it, everything went fine for about 1200 miles and then I get blinking CEL for about 30 seconds then it stops. Next day, blinking CEL for a minute or so, and then it turns solid. I took it back to the dealer and they say the only code pulled was P0300 misfire. They have no idea what’s causing it, and quite frankly I’m pretty fed up at this point. They’ve had my new truck longer than I have in the month I’ve owned it. Has anyone had something similar happen?
I have a 2019 GMC Sierra Elevation which I have just raised 2 inches using the ReadyLift 2.25 inch lift blocks in the rear and Bilstein 5100 shocks for the AT4 front and back. On the front I used the middle height adjustment slot which raises the front about 0.55 inch higher than stock. I have 40mm of rake at the moment with this setup. These Bilstein's are a huge improvement from the Rancho's that it came with from the factory. The ride is firm yet comfortable and the vehicle is a lot more stable with less body roll. The back sits firmly on the road and does not bounce and 'tail walk' from side to side over the bumps like it did with the Rancho's. I have a section of road that I drive regularly and the difference is very noticeable. Knowing what I know now, I would have changed shocks the first week that I bought the truck.
Hi everyone, new to the forum here and haven't seem to be able to find an answer after searching.
Purchased a 2020 1500 AT4 last summer(love the truck), and recently added the Firestone Ride-Rite kit to the rear(kit #2609). I also ordered the 2" spacer kit as recommended (kit #2366).
I'm having a bit of a problem with the install and was wondering if anyone else has added rear air bags to their AT4, and did you end up using the spacer or were you fine without it?
Problem is the air bags are slightly misaligned, and appear "under-inflated" with the spacer in there even when I have 10-20psi in them(there is about 500lbs in/on the box via a canopy and a Decked box system installed in the bed; I'd rather not have to try and remove these unless I absolutely need to, to diagnose the problem).
I know in the instructions it says to have 5.5-6.5" of space between the upper and lower mounts. So my next plan is to jack up the back of the truck enough via the hitch receiver to recreate the correct factory fender gap front to back(should be roughly 1.5" from the factory with no load if I'm no mistaken?), and then measure the distance between the new mounts.
Thoughts and/or someone who has added rear airbags to their AT4? I'd assume the Trail Boss would be very similar?
Hope this may help someone - 2021 GMC 1500 AT4 Carbon Pro 4Play Wheels ReadyLift 1.75" Leveling Kit
I just purchased a 2021 GMC Sierra 1500 AT4. These are the parts I installed:
4Play Wheels - Model 4P08 - 22x10 -18 Offset
Purchase 4 Hub-Centric Rings!
Nitto Terra Grappler Tires - 305/45/r22
ReadyLift Leveling Kit
4Play Wheels -
The -18 Offset is so incredibly close to the caliper hump but they clear. No spacers required. They look pretty good. They don't stick out excessively which my personal preference is slightly outside the fender but no where near the -44 Offset look. I personally do not care for solid black wheels on black trucks because you loose the wheel pattern. I live in Texas so 90% of every vehicle is a truck so you see plenty of them. These have Gunmetal Gray powder coat on the top of the spokes so there is some color offset but they mostly look like solid black wheels from a distance. I debated whether to get the all Gunmetal Gray for a major change to the look but I went conservative with black and Gunmetal spokes. You must purchase 4 Hub-Centric Rings. I got everything from Nick at BBWheels and they were awesome and very good pricing.
Part # - 66-3921 - 2019-2021 AT4 1.75" Leveling Kit:
I think instructions say like 3 hours. Ya No, at least not in my driveway with basic hand tools and floor jack and no experience. I also had no experience with CV joints so I made sure to run a strap around spindle so it did not fall back and bind or pull the CV joint out of the transfer case and take care of the angle and how much the CV joint was moving in and out, binding and making sure the strut bolt and strut bolt factory press on nut did not tear boot. This was not easy. Drivers side with setup took about 5 hours. Passenger side once I knew what I was doing took less than hour. Also did not have the large like 37mm socket for the spindle nut so I had to go to Northern Tool to purchase one. All they had was a 38mm and it worked. So I really do not know the correct size of the spindle nut but I got the job done and torqued. In the end for me the job probably rated a 7 out of 10 on difficulty scale simply because of taking care of the CV joints and getting the struts in and out without tearing the CV boots or pulling it out of the transfer case. One other note. I did not like the factory pressed on bottom strut nut. It is too tall and pointy and comes to close to the CV boot when working on the install and after. I removed this nut with a screw driver and mounted the strut bolt top down with a lock nut on the bottom on the side closest to the CV boot. Also got the ReadyLift from Nick at BBWheels.
Nitto Terra Grappler Tires:
To begin I made Discount Tire price match an Amazon price for 33x12.5 Terra Grappler's. Saved like $120 so do it. Next Discount said Corporate would not allow the sale of 33/12.5's because of the AT4's load rating. They said 305/45/r22's had the correct larger load rating so no big deal. They still sold them for the matched Amazon price. Tires ride great no noise look really good. My AT4 has the trailer option so I had 4 tire pressure sensors in glove box. I gave to Discount so they did not have to break down my stock wheels and remove sensors.
The only concern I have simply because this was my first 4 Wheel Drive lift kit I ever installed is CV angles? I Googled 2019/2020 GMC Sierra AT4 CV joint angles after lift and mine looks like everyone else's so? I put an angle finder on the top side of CV shaft before and after. Before on Drivers Side it was +4 after lift +12. Bottomside of Drivers Lower Control Arm +9 after lift +15 degrees. Passenger Side it was -10 after lift -19. Bottoms side of Passenger Lower Control Arm -10 after lift -18 degrees. Does anyone have any expertise on this? Does this seem acceptable? Not sure how or if these angles will change after alignment?
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