firehawk408

Hey new to this forum and new to my GMC Seirra. I just purchased an 04' 2500HD last week. It has the 6.0L with 4WD and about 16K miles. This truck is great.

Tonight on the way home I noticed when at WOT in second gear there is a flat spot or hesistation in engine acceleration right at 3800 rpm. Only happens in second gear at WOT and at 3800 rpm from what I can see. Only lasts about a second and the needle on the tach just chills at 3800 for a second you feel the acceleration pause then it continues to pull again. So far I can make it happen everytime. Truck is completly STOCK. Is this normal or what. Thanks in advance for your help.

TXsilverado

iTrader: (19)

click on that nelson link in my sig and he will turn your truck into a totally different animal

firehawk408

Nobody else experiencing this hesitation????

I took my truck into the dealer for it and they stated there were no faults, no bulletins and that my truck has the latest software. The tech compared it to another truck and the other truck was supposedly worse than mine. Don't really want to get tuning for it yet untill one my warranty expires and two I get someting done to it like CIA and cat back. Make the tuning worth it.

bud8fan

iTrader: (9)

i dont remember my hd having any flat spots but i do remember how much of a dog it was before adding a mac cai,magna flow aft-cat exhaust and then nelson tuning to the mix...fixed it right up. the cai was very noticable even before the tune...

firehawk408

hey bud8fan, how much was the nelson tune for your truck? I'm sure the flat spot will go away with tuning, I'll probably just wait until I get those mods to do the tuning.

bud8fan

iTrader: (9)

i dont remember but you can go to nelson performance web page and his prices are posted there...you wont regret it...his custom tune is bad *** dude..

BlownChevy

iTrader: (20)

How about a mechanical issue? what MPH does this take place at? Throttle Position?

SS_bnoon_SS

iTrader: (3)

It's called torque management. GM sees fit to pull timing out on the shift to second gear to keep the weak link bands from failing early. If you're going to do any heavy towing, you're going to want to keep at least some of that in there to preserve the life of your tranny. If not, have Bryan at PCMforless pull it off with his custom tune. His customer service is top notch and he answers all of my "stupid" questions via email, even when I'm not buying something from him at that particular time...

BLACKND

iTrader: (5)

I was thinking that too about the torque management, but wasn't too sure about how noticable it was with the HD. I assume you've got the 4L80E transmission, so you should be fairly safe to pull all the TQM and abuse mode out with the tune. Unless you plan on making alot of HP/TQ. Another thing to think about is that on the 03-up motors they have the electronic drive by wire throttle body. These seem to pronounce the loss due to torque management quite a bit. I know my 04 and now my 06 both have the flatspot there. My 99 sierra didn't seem to have that flatspot, and I didn't notice the torque management near as much.

firehawk408

BlownChevy it only happens at WOT and I can't currently remember at exactly what speed but I want to say around 55mph.

Sounds like torque management huh? It definetly feels like timing is just pulled back at the wrong time. I do not plan on any major mods, probably just intake and exhaust. It does have the 4L80E and the most it will do is eventually an occasiaonal towing of my firebird to the track.

Will have to look into the nelson tune. I know I should probably be asking these questions there but is it worth waiting for mods then tuning or tune now and again later after the mods. Thanks for all the replays. I love the truck!