tylerrmack

The torque converter would cause these intermittent vibrations like a misfire every few seconds (video)? Even in park, nuetral? I thought thr tranny was uncoupled in park and nuetral?

Mine was 11/15. I wonder if GM has made any changes to components since January? I have heard they quietly switch or update parts in factory that they figured I out are problems. Another symptom I forgot to mention was when very slightly easing off brake, just enough to barely move foward like in slow traffic, my truck surges/bucks. This is more prevelent when cold. Have you noticed this? Or noticed the vibe even at higher rpm in park?

Whats you build date? And does this shake look familiar to anyone else on here with a 6.2l?

I hope its not normal and can be fixed. Not something ai would expect out of such an expensive modern vehicle. If it was designed this way then I have no respect for GM engineers. At least exhaust can be remove from equation. Did they remove all the way to the exhaust manifold thus eliminating any leaks there? The only code I have ever gotten was p0300 for my fouled plug/misfire issue. I do notice the low side fuel pressure fluctuating at about the same frequency. Idle mid 40s psi with periodic dips into low 30s and 20s

Another thing. You should try revving up the engine (i used a golf club on the gas to keep a constant rpm better) and check the engine. Mine still shakes even at 1500 rpm and above. Which makes me think its doing it constantly and throughout driving but its harder to tell with road vibrations. Which leads to annoying paranoia when driving! I had a #2 misfire/failed spark plug fixed. Thought maybe it was oil from pcv. But put a catch can oil as a expirement. Turns out it works well. Oil pooled behind throttle body, then cleaned out and got oil in again within 100 miles. Then catch can installed. No oil for 500 miles. Took it off for expirement and oil back at 300 mile check. Didnt help vibration. Didnt try CRC cleaner yet. Thats next step before reinstalling catch can.

This is exactly what my truck is doing! Same engine/setup. I cant stand it. Did the exhaust help at all or would a new video reveal the same shake? If you find any fixes PLEASE post! Still thinking independent shop but havent had time. Either that or FORD.

Yes light came on p0300 random/multi misfire. No other codes. Had to have it towed because it wouldnt drive. Dealer said just random bad plug. Dont know how often that happens, seems more like "we dont know" With my limited knowledge I hooked up an OBD sensor and looked at some readings. 2 things i noticed were o2 sensors dont seem to coordinate well bank 1 vs bank 2 especially at idle and fuel pressure at idle is about 42psi with lots of flucuations and drops down in the 20s. I drove another 2016 sierra although it was a 5.3 and fuel pressure was more steady around 64 with mild fluctuations. Dealer didnt seem to know what to do with the comparison numbers or what it meant. They tried to look up some numbers but couldnt find anything. Figured i would yalk to them again at oil change or like i said earlier take it to an independent shop.

I took off the airbox and look behind the throttle plate and it look like excess oil being dump in from pcv. So i took the throttle body off and wiped out the front of the intake just behind the throttle body. Drove for about 100 miles then checked again and it was already slightly pooled up again. Wondering if this fouled my plug since #2 is right at the front and angle of pcv is pointing at it. Makes me wonder about oil seperators or if they are just BS. Also question whether all these problems that people express could be piston rings not seating well? Someone with more knowledge about poor ring seating want to chim in?

I have a 6.2l 2016 cc. Started noticing around 800miles. Took it to the dealer and they found nothing. Then 2 days later fouled #2 plug. They fixed that but still intermittent rough idle every 3-5 seconds feels like a miss. Waiting for amother fouled plug! Taken back multiple times and they cant find anything even though they admit its there. Sometimes its worse than others. Thinking it might be worse after 30+ mile highway trip followed by parking/cool down then it acts up on next drive idleing in park nuetral drive etc... Even still feel a shudder periodically when bringing it up to 1000rpm. Thinking about taking it to a independent shop.

I second , not bad gas. The dealer and the higher up gm tech tried blaming bad mexico gas and it may take a few tanks to clear it up and also suggested I was buying to cheap of gas. I had put 160gallons of premium top tier at that point. When I told them that, they had no response.

Deputy, What was the sensor that was replaced at same time as ecm?

Yeah i figure it would through codes if bad enough. I have had misfire code previously chalked up to faulty spark plug. Dont know if that was just BS. I figure these things have certain parameters that dont throw codes as long as its able to adjust. Just like it wont throw a misfire code unless its really bad multiple misfires. My question is that if its normal or is the system having to constantly adjust/compensate to stay just below the code throwing threshold?

2016 1500 6.2l. Having a intermittent rough idle stumble and even stumbles with increase to 1000k RPM. Its slight but noticeable. I have a cheap OBD2 bluetooth and Torque app for reading. I don't know how accurate it is, but figure all its doing is sending numbers, so should be find. With my truck idling fuel pressure is sporadic around 45psi with dips to 30 and even 22 psi, then sometimes up to 50psi. This seemed to be at about the same frequency as my stumble. The other reading if Fuel rail pressure which is much higher and cycles high and low but not as drastically. Is this normal? I tried attaching a screen shot. The numbers on the left are wrong but the graph shows the fluctuation. If someone knows the right reading to be expected or have a sensor to check their truck and see what the reading are, I would appreciate it.

I hooked up an OBD sensor and used a phone app to look at the sensors. When idling my fuel pressure jumps. On average 45psi then dips to 30 and sometimes up to 50, even down to 22 a couple times. The fuel rail pressure also fluctuates but not as drastically. Should these numbers be more constant?

I have noticed vibrations throughout my highway drives. Any on brand new smooth pavement my water is always jostling. Looking through forumns I dont know what to think. Everyone has a different fix. Anyway im lookig into the suggestion for fix here. 2016 denali 6.2l shortbox. I figured the mag ride was going to be super smooth but its definetly not what i expected or something is wrong. Looked under my truck. No spring spacers like on other forums (why do some have these and others not?, is it different grades of suspension or did they come leveled?). Also i have marks on my rear axle and drive shaft. Do you think the factory did this or was there some sort of out of factory repair on it that i wasnt told about?