4L65E shift problems denali
 

Wife drove to work fine . 12 hours later coming home it ran 3500rpms to go 55 . problem is she was about half way home before calling . Fluid is not perfect but i have seen much worse . have reverse and takes off fine in drive .around 25-30 the problem starts . it will shift if you back off a second , but then get to around 50 and running 3500rpm . only engine codes are P0449 vent solenoid and P0455 purge solenoid . no tranny codes . temp gauge for tranny was around 150* . Had the check engine light on for a few months , but not sure if it was both codes or just one until today . checked all tranny related fuses under the hood . would either of the emissions codes cause such a problem ? trying to convince myself we won't need a new tranny ! thank you

Re: 4L65E shift problems denali
 

3-4 clutches burned up?

Re: 4L65E shift problems denali
 

What year Denali? '07-'08? I wouldn't think that the purge and vent codes would cause transmission issues. I just saw those codes on a friend's Tahoe. Weird thing is, they also had an alert for "service stabilitrac". It shifted fine to me but it might have an effect on shift strategy, points etc?

On our '04, rpm would flash on the 1-2 shift. It went that way for quite a while until we saved up for a rebuilt that I installed.

Clinebarger is pretty well regarded as an automatic trans oracle here. He helped me spec out the parts and upgrades for our 4L65E. Couldn't be happier with the transmission which is going on a couple of years of my wife abusing it.

Re: 4L65E shift problems denali
 

06' ,,, yes 3-4 it is . I have looked at used with miles all over the place anywhere from 700 to 1200 $ . rebuilt with 6 month warranty 545$ but they don't ship so I drive 6hrs or pay them to meet half way . I have changed many trannys over the years always on my back and no tranny jack . regular jack with a piece of plywood . Not doing that now . one vehicle down because of a deer .
rent a jack $80 .. will buy one for $200 before doing that . Local reputable shop $1550 with a year warranty . took it in yesterday and they started today . everytime I looked at the math I would save maybe 400$ by doing it myself , but little or no warranty and taking a day off work . bit the bullet but struggled ... first time I have ever paid someone to do something on a car that I am capable of doing . getting older , but don't know if I am getting smarter or not !!