ToxicWS6

i have a 2004 gmc sierra 5.3L with prc 2.5 stage heads and a mid range cam, has a built 4l65e that was installed by previous owner so details are unknown, has a 3600 stall torque converter, 5.13 gears and 38s

the issuse its had since ive gotten it is if i drive around in 3rd everything's all good and dandy and when i hit 45mph + i can manually shift it into 4th and it goes into 4th and everything's good, well if i drive around in 4th (D) taking off from a stop it will take off in 1st maybe the first 3-5 times then it will not shift back into 1st no matter what, accelerating it wont down shift and coming to a complete stop nothing, even if i manually downshift into 1st it stays in 2nd and takes off like a slug, it does pop a solenoid code (i haven't drivin the truck in 6-8months and finally getting it back on the road so i dont remember witch but it had to do with first or second gear) if i turn the truck off and let sit for a few mins it all resets and u get 1st gear back as long as u dont use D to drive in

would this be the transmission taking a **** or a bad tune with the stall converter?

thanks, and sorry for run ons/grammar, on phone atm

mrvedit

A code is not something to just ignore - I immediately suspected a sticking solenoid. I would suggest replacing both shift solenoids and the 3-2 downshift solenoid (which can cause strange problems.) That is only about $40 plus your time to do it.

That won't guarantee a fix, but the first step is to always fix all trans and engine codes and go from there.

ToxicWS6

im not ignoring i just didnt know if it was a side effect of a higher stalled converter, would u say its transmission related then?

mrvedit

No, a higher stall converter will cause codes related to slippage, not solenoid codes. (EDIT: Appears I was wrong - see below - a high stall converter can cause solenoid codes.) A high stall converter can also cause engine misfire codes. Any of those codes can cause the trans to go into "limp" mode which then starts in 3rd gear. Also these codes can prevent the TCC from locking and give a very harsh 1-2 shift.

Hmmm, you did mention the trans started in 2rd gear. Actually that was probably limp mode and you started in the super sluggish 3rd gear.

If you haven't been tuned for a high stall converter, that should be your first step. If problems persist, replace those three solenoids.

flattusmaximus78

iTrader: (1)

That happened to my 02 z. Converter slippage cause it to throw a shift solenoid code. It got stuck in 3rd I believe. Set the code to no report and good to go.

ToxicWS6

i might be getting stuck in third then not 2nd, and i have hptuners now when i didnt back then, yeah i can clear codesnor let truck reset so, the guy i got this vehicle from put a shitty tune on the rest of the truck so i was guessing the transmission wasnt any better

thanks guys! my title came in the mail today for it so when i get back from vacation ill try it out, thanks!

poltergeist 02

iTrader: (65)

Have your tuner delete P0751 and P0757. I had the same issue and this took care of it.

mrvedit

Thank you for the information that a high stall converter can cause a solenoid code - I corrected my post in #4. Always eager to learn.

Hopefully that will work for the OP and he can report back if/when it does.

ToxicWS6

i will report back when i get a chance to do this, i dont get back crom T-day vacation till 2nd so dont hold yalls breath lol

ToxicWS6

so i got the tune in my truck, i deleted the above codes and adjusted some other non tranny things and have been driving around in D for the last 2 days with no issues at all, truck drives awesome, only thing i want to play with now is try to up first gear shift mph so it dosnt shift so soon into 2nd then feel like a pig as the converter slips

thanks guys! it fixed my problem!

mrvedit

Congrats on fixing it with a tune. And thanks for updating us.
I tweaked my shift points dozens of times before I had it the way I like.
HP Tuners or EFI Live can really make the car more enjoyable.

l96a1

Thanks for the update

Roarin_8

iTrader: (5)

I know that this is an old thread but also make sure to delete PO756, I was getting that code randomly and causing the car to stay in 3rd. Using the Aeroforce Interceptor to read the DTC and then clear it would cause the trans to get back first and second, so I deleted it with HP Tuners and no more issues with it.

Looking at my HP Tuners, I don't even have a PO757 listed and PO751 is still checked to go off but I've never had any issues with that particular code so I'm leaving it alone.