I have a 2017 Colorado Z71 with the Duramax. So far its been ok. I love the truck, it drives exceptionally well(minus the OE shocks) but there are glaring issues with the diesel drivetrain that Chevy keeps having issues with. Tuning it would be ideal but trying to find deletes is near impossible now with the EPA fines. I dont mind the emissions though since it seems less intrusive compared to the full size models.
Throttle lag is ATROCIOUSLY bad. I mean, get on the highway and pray to god the truck responds bad. I mean, take a left turn over an intersection and hope you hit the gas early enough to clear the intersection before getting T-boned bad. I put a pedal commander in it and tried a few settings. Truck acts funky on anything but City -3 or City -4. It acts like someone is pushing the pedal down when youre even sitting in the driveway. So on City -3 is the place that feels the best and it removed all of the throttle lag with none of the other side effects. Simple install but hefty price for a glorified tuning device($399). I got mine used for half price and it was still a chunk of change for something that gives no extra power or trans tuning. With the City -3 setting is how Chevy should have programmed the throttle on this truck.
I had DEF issues for a while early on. Replaced the sensor more than once along with several reprograms due to TSB's and one recall on the regen cycle. It still does not tell me when it regens or when im low on DEF fluid. The dash does have the option of looking at the DEF fluid level though so i just check it every once in a while to make sure im not running it dry. The truck will not go into limp mode though. Even with the DEF not working it will set a CEL but run perfectly fine. Compared to full size trucks that throw you into limp mode this was quite surprising and a breath of fresh air.
I have also had issues during the colder months that Chevy still cant fix. This is my biggest pet peeve with this truck to date and the one reason why i keep contemplating trading it in on a Ranger FX4. At any temp below 45F during a cold start the truck will have idle surge. This has happened since 10k miles up to today's mileage of 40,195. It did it this morning and its right at 45F. The truck will start, both by key and by remote start, and once it settles to 850rpm it will start to surge between 850-1000. Chevrolet tried reprogramming it 3-4 times without any fix. They replaced the fuel filter housing at 10k when they found a crack in one of the filter bowls. No fix. They tried to drain the fuel tank and get fresh diesel in it, still didnt fix it. I have added every anti-gel under the sun to see if the fuel was freezing in the line but that didnt do anything to help. The odd issue is that it only happens when cold. Once the truck warms up it runs/idles perfectly fine. So my plan for now is to use the remote start to warm it up and then get in and go.
Transmission is a 6 speed unit - 6L50 - which is an oddball. It feels like it was tuned for a gas engine and has such a terrible shift schedule you feel like it has either too much line pressure or too little line pressure. GM flushed the fluid to the updated TSB fluid at 30k miles and it has gotten better but still isnt 100% clear yet. The shift knob in the truck is a pile of hot garbage and your knee will hit it. I swapped a Camaro knob into the truck for $68 and a small amount of wiring(two wires and some heat shrink). A tune supposedly will change the shift schedule and pressures to where they need to be but i dont want to tune this until im over the 8/80k emissions hump.
Suspension up front made noise, ended up being the sway bar end links. GM replaced them with an updated part. The front air dam is also too low which scrapes on everything. It takes the truck from a 21-23 degree approach angle to a 18 degree approach angle which is worse than some cars. Takes about 30 min to remove and i notice zero MPG hit when it was off. I replaced the factory plastic skid plates with the GM performance ZR2 style skid plates for $240 which bolt right into existing tapped holes.
Stock OE twin tube shocks are flat garbage. Hit a bridge expansion joint and it will nearly send the rear end skyward. They have so much compression damping dialed it is flat scary to drive over anything more than a small bump at speed. ZR2's have the slick DSSV dampers which cure this entirely. For us not in a ZR2, i swapped in the Bilstein 5100's set to level the front at 1.3" and the rear is stock height. The monotube 5100 dampers feel sooooooo much better all around, at speed, slow offroad, rain....just completely transforms the truck.
OE headlights are garbage. They are projector housings but use a halogen bulb. Easily some of the worst headlights ive ever used. Swapped a set of JDAstar cheap-o LED bulbs into them and that improved visibility tenfold at night. Also swapped the fog lights to a set of JDAstar bulbs which added to the light output.
The brakes are insanely good. 4 piston floating caliper up front and 1 piston sliding caliper in the rear. The rotors are supposed to be that duralife stuff and wear is non-existent at 40k miles so far. They did the homework required on this braking system for sure. Chevy did change the fronts to sliding calipers for the 2021 model year for some reason though as i was at the dealer the other day to get serviced and looked at a ZR2 on the lot. Dont know why they would get rid of a floating caliper except for cost reasons.
Other than those, its not a bad truck at all. It tows 5500ish pounds extremely easy. They state it only has 181hp but people have dynoed them at or above that horsepower mark at the wheels. You can feel the 369lb-ft of torque though. Truck pulls hard from a stop and with tow mode on doesnt have the torque modulation as bad which helps getting up to speed. Visibility while towing is also really good for a mid size truck and you dont really feel like you need extended mirrors.
If you have any other questions please let me know. Here is a photo of my truck as it currently sits.
ZR2 sliders, 255/65R17(OE size, but want to go to 265/65R17 off a ZR2), 1.3" level with Bilstein 5100's, GMPP skid plates, CBI style ditchlights, Gator tri-fold tonneau....etc.
Throttle lag is ATROCIOUSLY bad. I mean, get on the highway and pray to god the truck responds bad. I mean, take a left turn over an intersection and hope you hit the gas early enough to clear the intersection before getting T-boned bad. I put a pedal commander in it and tried a few settings. Truck acts funky on anything but City -3 or City -4. It acts like someone is pushing the pedal down when youre even sitting in the driveway. So on City -3 is the place that feels the best and it removed all of the throttle lag with none of the other side effects. Simple install but hefty price for a glorified tuning device($399). I got mine used for half price and it was still a chunk of change for something that gives no extra power or trans tuning. With the City -3 setting is how Chevy should have programmed the throttle on this truck.
I had DEF issues for a while early on. Replaced the sensor more than once along with several reprograms due to TSB's and one recall on the regen cycle. It still does not tell me when it regens or when im low on DEF fluid. The dash does have the option of looking at the DEF fluid level though so i just check it every once in a while to make sure im not running it dry. The truck will not go into limp mode though. Even with the DEF not working it will set a CEL but run perfectly fine. Compared to full size trucks that throw you into limp mode this was quite surprising and a breath of fresh air.
I have also had issues during the colder months that Chevy still cant fix. This is my biggest pet peeve with this truck to date and the one reason why i keep contemplating trading it in on a Ranger FX4. At any temp below 45F during a cold start the truck will have idle surge. This has happened since 10k miles up to today's mileage of 40,195. It did it this morning and its right at 45F. The truck will start, both by key and by remote start, and once it settles to 850rpm it will start to surge between 850-1000. Chevrolet tried reprogramming it 3-4 times without any fix. They replaced the fuel filter housing at 10k when they found a crack in one of the filter bowls. No fix. They tried to drain the fuel tank and get fresh diesel in it, still didnt fix it. I have added every anti-gel under the sun to see if the fuel was freezing in the line but that didnt do anything to help. The odd issue is that it only happens when cold. Once the truck warms up it runs/idles perfectly fine. So my plan for now is to use the remote start to warm it up and then get in and go.
Transmission is a 6 speed unit - 6L50 - which is an oddball. It feels like it was tuned for a gas engine and has such a terrible shift schedule you feel like it has either too much line pressure or too little line pressure. GM flushed the fluid to the updated TSB fluid at 30k miles and it has gotten better but still isnt 100% clear yet. The shift knob in the truck is a pile of hot garbage and your knee will hit it. I swapped a Camaro knob into the truck for $68 and a small amount of wiring(two wires and some heat shrink). A tune supposedly will change the shift schedule and pressures to where they need to be but i dont want to tune this until im over the 8/80k emissions hump.
Suspension up front made noise, ended up being the sway bar end links. GM replaced them with an updated part. The front air dam is also too low which scrapes on everything. It takes the truck from a 21-23 degree approach angle to a 18 degree approach angle which is worse than some cars. Takes about 30 min to remove and i notice zero MPG hit when it was off. I replaced the factory plastic skid plates with the GM performance ZR2 style skid plates for $240 which bolt right into existing tapped holes.
Stock OE twin tube shocks are flat garbage. Hit a bridge expansion joint and it will nearly send the rear end skyward. They have so much compression damping dialed it is flat scary to drive over anything more than a small bump at speed. ZR2's have the slick DSSV dampers which cure this entirely. For us not in a ZR2, i swapped in the Bilstein 5100's set to level the front at 1.3" and the rear is stock height. The monotube 5100 dampers feel sooooooo much better all around, at speed, slow offroad, rain....just completely transforms the truck.
OE headlights are garbage. They are projector housings but use a halogen bulb. Easily some of the worst headlights ive ever used. Swapped a set of JDAstar cheap-o LED bulbs into them and that improved visibility tenfold at night. Also swapped the fog lights to a set of JDAstar bulbs which added to the light output.
The brakes are insanely good. 4 piston floating caliper up front and 1 piston sliding caliper in the rear. The rotors are supposed to be that duralife stuff and wear is non-existent at 40k miles so far. They did the homework required on this braking system for sure. Chevy did change the fronts to sliding calipers for the 2021 model year for some reason though as i was at the dealer the other day to get serviced and looked at a ZR2 on the lot. Dont know why they would get rid of a floating caliper except for cost reasons.
Other than those, its not a bad truck at all. It tows 5500ish pounds extremely easy. They state it only has 181hp but people have dynoed them at or above that horsepower mark at the wheels. You can feel the 369lb-ft of torque though. Truck pulls hard from a stop and with tow mode on doesnt have the torque modulation as bad which helps getting up to speed. Visibility while towing is also really good for a mid size truck and you dont really feel like you need extended mirrors.
If you have any other questions please let me know. Here is a photo of my truck as it currently sits.
ZR2 sliders, 255/65R17(OE size, but want to go to 265/65R17 off a ZR2), 1.3" level with Bilstein 5100's, GMPP skid plates, CBI style ditchlights, Gator tri-fold tonneau....etc.
