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slight shake or miss on my 2008 6.0 suburban ltz 4wd



I installed a new 6.0 motor with high volume oil pump on my 2008 6.0 LTZ suburban. It has only 500 miles on it at the moment as of 9-5-2019. I installed a new intake, new throttle body, (relearned) new radiator, new plugs, wires, injectors, fuel pump and new heavy duty motor mounts, I have this slight shake at idle and you can feel it in the performance of the truck when driving down the freeway as if something is holding it back, Its not throwing any codes, engine light is not coming on. Had a guy that all he does is reprogram cars and trucks with his computers and when he hooked his high dollar stuff to the truck, the rpm went to zero while it was running and said it was a cam position sensor but when he disconnected it it went back to normal. my regular mechanic hooked up his diagnostic computer (Zuess) right after and it had no codes and we cant find out what is up. Maybe the guys high dollar stuff was messed up.  Some guys are saying its the trucks computer but its not showing any codes, it runs fine but it should be absolutely purring like a kitty cat and there should not even be the slightest movement. The guy with the computers said that it has the fuel efficiency program on it that drops to 4 cylinders from 8 to save on fuel, he said the system was on and asked if I wanted it turned off for 250.00. I didn't do it. something is up and its driving me nuts. anybody have an idea at all? the #1 cylinder failed on the original motor and the traction control code came on and said it needed to be serviced. After the motor was replaced it did not come on again and there was no code for it as well. just for some history. Please help

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All engines will have some vibration at some point.  If you are not throwing any codes, it is time to ignore the slight vibration at idle, that very likely is not as bad as you think.  Chances are you are just focusing on something that is normal.  Does you truck have the variable displacement or whatever GM calls their flavour of dropping off cylinders on the highway?  Not sure I would have paid $250 for the guy to make a single change to disable it when he is already likely at the screen to do it.  Did he charge you for testing it?  If not, then he is a decent guy, but if he charged you to simply ask you for more money to tick off a box, I am not sure I would be able to find the spot where he parked his car.

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its a 1500 suburban ltz . Gm should have built these engines with a high volume oil pump. it was causing motors to fail and many people were misdiagnosing the oil sensor when it was the pump. the vibration is not normal. the new motor only has 500 miles on it and it does have the fuel displacement feature on the vehicle. the guy makes his living doing the computer thing but i wasnt gonna chance him messing it up and making things worse. 250 was ridiculous though and i would  never pay that amount, beside he was already doing work for my mechanic. ive looked at 3 other trucks older than mine and they had no hesitation at all. smooth under the hood. everything is new on mine and i still got an issue. its gotta be computer related

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