My friend has a 03 silverado 5.3, an he has had a nelson Tune installed for a few months now. Well latly he has been saying that its not running as good. He has the dual tunning for 89/91 or what ever the top two octanes are. But even when he runs 91oct or 89 or 87, it always runs the same. He said it feels like the TM is back to stock an that it doesent even want to spin the tire anymore. He had one thougght that it might be from a GM computer. Cause he had a friend from a GM dealer adjust his truck with a computer cause he bought new tires that where just one or two sizes smaller than stock, so he was only tring to recalobrat the Spedo thing. An he was wondering if his tune got messed up when they hooked up the GM computer to it. He knew the guy that made the adjust meant so he knoes he didnt screw his up on purpose. But what do you guys think might be making his truck run so bad?

 

they could have reflashed the computer with the "latest updates" while he was at it thinking he was doing a favor ( not realizing it had been tuned ) and basicly set it back to stock.

 

If the dealer flashes any updates, it overwrites your tune back to stock.

 

Well that sounds like that could of been the problem. But my friend asked another friend(Mr.goodwrench) an he said that he doesent think that should of messed with his Tune, cause when you adjust for new tires or the speedo thing it doesnt inter fear with any of the PCM stuff. Is that true or do you have to go throgh the PCM?

 

When who adjusts for tires? GM? They don't do that stuff, do they? Are you talking if you do it yourself with a handheld tuner? True, those boxes allow for individual parameter changes. But GM thinks that they're the only ones who go into your PCM, so when you need an update, I believe they just take the latest update for your vehicle and overwrite your present one with it. It's much simpler for them this way.

I would bet that if you simply adjusted for tires with a Predator (let's say), then went in and got a flash with the latest trans update from the dealer, when you left, you would have the stock tires programmed in again. You would then have to get the Predator and do the tire reprogram once again. Just a hunch.

 

IOf it was reflashed it will state it on the service invoice. also if he calls Nelson he will get updated for shipping cost.

 

in order for him to adjust anything in the pcm he has to reflash it. this will overwrite the tune and it is gone.

 

The dealer can and will change the tire sizes in the PCM to match what you have on the truck. Not all will do it, but they can, my local dealer will. Just Call Nelson, explain to him that the computer was reflashed by the dealer and get him to send you a new tune.