07 Nbs Missing/surging On Street But Idles Smoothly.

hubbycap · October 9, 2007

Had the Silverado nbs 6 weeks now and after my initial elation (3 days) of what a truly well thought-out vehicle I had purchased, I began to notice what seemed like a rapid-fire surging or misfire/gas starvation sensation at street and highway speeds, mostly unloaded constant speeds. At first I thought it the unfamiliarity with the new vehicle/tire characteristics. I read with interest the discussion on this forum on tire pressures, suspension and road harmonics. I did, lower my rear tire pressure to 32psi from factory spec of 35# and found the ride much improved, but the unnerving power loss/surge remained and was irrespective of V4/V8 mode, which works flawlessly.

I’ve now been to my dealer 3 times with the problem: On the first trip the problem was acknowledged and said to be found existing on similarly equipped Chevys (5.3L iron, 4-speed auto, 3.42 locker) in dealer stock and their shop truck. Dealer said GM recommended a fuel system flush and that I run a couple of tanks of top-tier gas like Chevron through it (puh-leeese.) Playing the game I did, expecting nothing and was not disappointed, but playing the game like a trooper all the same. Next, I discovered that the tranny was extremely low on ATF, barely showing on stick. My thinking was the power loss could possibly be air in hydraulics or something. Since DEXRON VI is only available at a GM dealer and maybe NASA I went back and was topped off. No charge, No change. So back I go, this time they said a TSB described my problem very closely and there was ECM and tranny (TCM?) program updates. They likewise had no effect.

3100 miles today and I took the unit back for an oil change and an auto door-lock problem (fixed with a BCM update.) While there, I asked to talk to the service manager about my annoying power problem. I told him my Tach also fluctuated 100-200 rpm on level road with constant accelerator pressure. During the meeting that the shop foreman also attended, I was told that the Tach variation was normal and GM sez that they are aware of the problem. I was assured that they (dealer) would be vigilant (as always) in making sure that new programming was flashed as it became available. Otherwise, there were no codes; there is no warranty-reimbursable action; and enjoy my new pickup and have a nice day (I paraphrased this last sentence, it was much more diplomatic than this, but un-entertaining.)

Has anyone else noticed this irregular engine performance? I am crazy about this new truck in every other way, but, as good of an engineering job as I behold in this model, I cannot believe GM would let such an obvious drivability issue survive to the assembly line. I would appreciate feedback as to whether my copy is unique and defective or if this is commonplace and I should grow to like it. Maybe I’m just an anal SOB.

mweedy · October 9, 2007

Had the Silverado nbs 6 weeks now and after my initial elation (3 days) of what a truly well thought-out vehicle I had purchased, I began to notice what seemed like a rapid-fire surging or misfire/gas starvation sensation at street and highway speeds, mostly unloaded constant speeds. At first I thought it the unfamiliarity with the new vehicle/tire characteristics. I read with interest the discussion on this forum on tire pressures, suspension and road harmonics. I did, lower my rear tire pressure to 32psi from factory spec of 35# and found the ride much improved, but the unnerving power loss/surge remained and was irrespective of V4/V8 mode, which works flawlessly.

I've now been to my dealer 3 times with the problem: On the first trip the problem was acknowledged and said to be found existing on similarly equipped Chevys (5.3L iron, 4-speed auto, 3.42 locker) in dealer stock and their shop truck. Dealer said GM recommended a fuel system flush and that I run a couple of tanks of top-tier gas like Chevron through it (puh-leeese.) Playing the game I did, expecting nothing and was not disappointed, but playing the game like a trooper all the same. Next, I discovered that the tranny was extremely low on ATF, barely showing on stick. My thinking was the power loss could possibly be air in hydraulics or something. Since DEXRON VI is only available at a GM dealer and maybe NASA I went back and was topped off. No charge, No change. So back I go, this time they said a TSB described my problem very closely and there was ECM and tranny (TCM?) program updates. They likewise had no effect.

3100 miles today and I took the unit back for an oil change and an auto door-lock problem (fixed with a BCM update.) While there, I asked to talk to the service manager about my annoying power problem. I told him my Tach also fluctuated 100-200 rpm on level road with constant accelerator pressure. During the meeting that the shop foreman also attended, I was told that the Tach variation was normal and GM sez that they are aware of the problem. I was assured that they (dealer) would be vigilant (as always) in making sure that new programming was flashed as it became available. Otherwise, there were no codes; there is no warranty-reimbursable action; and enjoy my new pickup and have a nice day (I paraphrased this last sentence, it was much more diplomatic than this, but un-entertaining.)

Has anyone else noticed this irregular engine performance? I am crazy about this new truck in every other way, but, as good of an engineering job as I behold in this model, I cannot believe GM would let such an obvious drivability issue survive to the assembly line. I would appreciate feedback as to whether my copy is unique and defective or if this is commonplace and I should grow to like it. Maybe I'm just an anal SOB.

I have a new Denali with a 6.2 and contacted the dealer 1 time and showed up at his door 1 time with the exact same senerio. I was also sent packing with the same we know about the problem mojo. high test made it better. I think it's a computer adjusting the timing for best performance/fuel economy issue. I was thinking of sending a letter to GM directly.

ballon78 · December 15, 2007

Mine surges too, i notice it at 30 mph on back road just barley on the gas. The other day i had it in 4x4 on the highway about 45-50 mph and it was doing it bad, with a slight load. I have exhaust i just put on and so now i notice it more, i also have a diablo programer and it does it with and without the programer, i was hopping when i put the tune in it would go away but it didn't.

redvett · December 15, 2007

I suggest you call customer assistance and voice your complaint. They will give you a complaint number then wait a couple of weeks, and if you haven't had a fix or response call again. GM maybe in the process of fixing the problem. Most of all DO NOT get a custom tune before its fixed. Warranty claims & complaints are a tracking device and if you fix it your self or ignore it GM has no way of knowing there is a problem.

Be patent and friendly with your dealer & customer assistant.