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I am having an issue that the dealer can't figure out, and after 3 months, GM tech support tells me it is "normal", so if any of you can see if you can replicate the issue I am having that would be a great help!

After about 3 miles driving, I have to cross a busy intersection. Accelerating at about 3/4 throttle, at between 2500RPM and 2750 RPM the truck bucks. Tach drops, MPH drops, about .25 sec, then kicks back in hard. It is worse when cold out. Normally does this once or twice, then will not do it again for the rest of the day. I have had a few times where it did it every time I had to accelerate from 1st or 2nd gear for my entire 45 minute commute. The dealer could not figure out what was wrong, but did feel it happen every morning when they drove it. They had me turn off traction and stability control, same thing. Also, no traction control indicator when it does it. If I accelerate at 1/2 throttle, no issues, if I accelerate at FULL throttle, still no issues! I decided to monitor the fuel injector current with a scope, and saw that the injectors are shutting off for .25 seconds. With this information, the dealer took the truck for another week to record more data. They sent it to tech support who did nothing for a month. I finally called GM Tech support directly and pushed them a bit. After another week, they called back and said that the truck is working as designed. They said it is the torque management system. What they can't tell me, is why they would design the torque management system to shut the engine down for .25 seconds, what is it sensing that is making this happen? And why would it happen only at 3/4 throttle and not full throttle? And why would it start at about 58000 miles and gradually get worse until it does it every day if it is a "design feature"?
Thanks for any input anyone has.
 

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So it didn’t start until almost 60k miles? Interesting. I have 65k on my 2017 Canyon and have no issues. I deleted at 45k and had no issues prior either. I can’t say I’ve heard of anyone on the facebook groups or the ColoradoFans.com page say they had any issues like this. You might post there too as it seems to be more active than this site. Might find more/ quicker answers.
 
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55000 on a diesel 2017 Canyon. Same issue so bad that sometimes it stalls out. Dealer say newly designed fuel pump night be the answer. So far we've replaced injectors, filters and fuel pump. Waiting on what dealer claims is 4th generation fuel pump to "try".
 

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Could be an electrical issue. There is a known issue with our trucks having a rubbing problem on a wiring harness near your drivers front tire. Might be worth investigating. I mean, if you've replaced all the fuel parts, I would probably start looking elsewhere.
 

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I am having an issue that the dealer can't figure out, and after 3 months, GM tech support tells me it is "normal", so if any of you can see if you can replicate the issue I am having that would be a great help!

After about 3 miles driving, I have to cross a busy intersection. Accelerating at about 3/4 throttle, at between 2500RPM and 2750 RPM the truck bucks. Tach drops, MPH drops, about .25 sec, then kicks back in hard. It is worse when cold out. Normally does this once or twice, then will not do it again for the rest of the day. I have had a few times where it did it every time I had to accelerate from 1st or 2nd gear for my entire 45 minute commute. The dealer could not figure out what was wrong, but did feel it happen every morning when they drove it. They had me turn off traction and stability control, same thing. Also, no traction control indicator when it does it. If I accelerate at 1/2 throttle, no issues, if I accelerate at FULL throttle, still no issues! I decided to monitor the fuel injector current with a scope, and saw that the injectors are shutting off for .25 seconds. With this information, the dealer took the truck for another week to record more data. They sent it to tech support who did nothing for a month. I finally called GM Tech support directly and pushed them a bit. After another week, they called back and said that the truck is working as designed. They said it is the torque management system. What they can't tell me, is why they would design the torque management system to shut the engine down for .25 seconds, what is it sensing that is making this happen? And why would it happen only at 3/4 throttle and not full throttle? And why would it start at about 58000 miles and gradually get worse until it does it every day if it is a "design feature"?
Thanks for any input anyone has.
I have a 2016 Colorado Z71. Around 63000 I started to get a bucking and mine turned out to be a bad Torque Converter. I don't think we are having the same problem but thought I would mention it.
 
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