First post...so hello! Looks like a great site! Looks of info on headers which will be an upcoming mod so I promise to search for info first!

Anyway, I bought my 09 SD slightly used (19k miles). Truck is great, but seems to have quite a bit of hesitation at low rpms. Almost feels like a miss-firing cylinder. It is worse when truck is cold. It is almost dangerously hesitating until it warms up for a few minutes. Above 2000rpms, all is good and smooth.

No codes are coming up, and the dealer acknowledged the complaint but said it was my Volant intake. I told them it was there before the intake too, but they then backtracked and said it was normal in the 6.2L. They drove around with the scan tool for 9 miles and nothing abnormal came up.

Any thoughts? I run good gas, cleaned the tbody, ran Seafoam, etc...
My next step is a tune via Blackbear but there is a long wait on the datalogging tool. Just curious if anyone had this in their new SD??

 

Better get the problem solved before the tune as it will void your warranty and dealers know how to find out if it has a aftermarket tune.

 

sounds like torque management to me...

 

I hope it is just the TM, but I've had 2 silverados, 2 lightnings, and many, many cars over the years...and never had a hesitation issue like this since my first car--a 4 barrel 1968 Mustang that needed tuning!

There was a bunch of oily-like engine detailer sprayed in the engine bay (felt like armor all) when I got the truck. It looked great, but I wonder if some of that stuff messed with something....

 

I believe it is a combination of issues that all add up to create what feels like a sluggish truck. One is Torque Management as already stated. Two is every year the ETC equipped trucks have been continuously desensitized a little more than the previous year (at least this was true in the earlier year models due to complaints of touchy accelerator peddles) and is harder to correct in the ’06 + trucks. Third is I feel due to the size of the intake runners and valve size on what is still a relatively small motor, it causes low speed drivability to suffer slightly (I noticed quite a few 6.2L owners saying their motors have a less than smooth idle). This is one time that I would quit visiting the dealer as they will not be able to do a thing for you, because in all reality there is nothing wrong with your truck.

Bottom line is I feel that you can solve all your issues by simply having your truck tuned. All of your issues will be addresses except port size, but properly tuned the motor will tend to make better use of those wonderful heads. The statement of the dealer being able to see that the truck was tuned is also correct, as every time the vehicle is flashed it leaves a signature of sorts. The only way around this is to purchase a spare ECM to have tuned and keep your original for warranty issues. Even doing this they will see a battery disconnect, but I don’t feel this would upset the apple cart. The only other item of concern would be is if you had the TCM flashed as well.

 

buy replacement, used, PCMs on ebay for the aftermarket tune and put the stock PCM/TCM on the shelf to be put back in when warranty work is being done. I bought both for $80 + shipping. You'll have to get them programmed to your VIN, after that tune away. Find a tech at a GM dealership that will load the factory tune for you after hours. Slide them a few bucks for their time. Look at the service number on your current PCM and buy ones with the same service number on Ebay.

 

I've had 2 gmt900 6.0's and now a 2010 6.2 and none of them have had that issue,stock
No way tm or volant are going to do that.

I had a tune in my 07 that did the same thing.
When it was cold it ran so bad i would have to pull to the side of the road so other vehicles wouldn't run ito me.
Something to do with the idle tables I think.
Wheatley fixed it for me

You bought it used,
10 bucks says there is a crappy tune in it.
First thing I would do is have the dealer re-flash the stock tune
so you know what u have.
20 bucks says that will fix it

Don't put a blackbear tune in it until you have a stock tune to save

 

All good points....thanks for the info! I think having the dealer reflash it may be worth the effort. I don't think the last owner messed with the tune (the guy installed a topper and all the xm presets were on Bloomberg, MSNBC, etc...so I think he was older), but who knows what a dealership did somewhere else!

I am really curious to drive a new SD or Escalade and see if they have the same issue. I'm sure they must run smoother than mine does or they would have a major customer issue with a truck that bucks and stalls enough to spill your coffee.

In any event, I will buy the spare PCM and wait for Justin's tune to be installed when the equipment becomes available. That will be a long 2 months!!

 

I've heard roumors about the dealer knowing that you have a tune. This has been both confirmed and denied by gm service techs. Either way, if you're smart about it, it won't affect your warranty. For several reasons. You stated the truck was purchased used. Can the dealer PROVE the truck was NEVER tuned before you bought it? Also from what I've been told, the dealer can tell that the tune has been changed. If you re-flash the stock tune, they can not see what was changed. Maybe you changed tire size and wanted to correct your speedometer? You also have magnuson moss on your side. In order to deny warranty they have to prove that a modification caused the failure. Ie, you re-tune and the differential goes out, the dealer has to prove that 1. The tune is what caused the failure, and 2. No stock vehicles have had similar problems. That being said, I went from a stout 2000 with drive by cable throttle body to a 2008 drive by wire and experienced a hesitation that IMO was dangerous. A good tune later and I'm happy. I'll also note that I destroyed a transmission recently (I seem to be good at that) and the transmission was warrantied with my tune still installed, and long tube headers installed with tires larger than my truck came with (however they are a factory option)