Transmission Codes P1870 and P1811

2001 Oldmobile AURORA P1811.
TRANSMISSION REBUILT. NEW SOLENOID BOOST KIT PUT IN TRANNY LOTS OF INVESTIGATING. Question: MY AURORA IS SHIFTING HARD IN EVERY GEAR. IT DOESN'T DO IT ALL THE TIME OR EVERY DAY BUT DOES SEEM TO DO IT AFTER YOU SIT FOR A WHILE OR DRIVE FOR A WHILE! SOMEONE SAID MY MANIFOLD GASKET COULD BE LEAKING CAUSING IT TO DO THIS!!

PLEASE TELL ME WHAT YOU THINK MY CAR HAS BEEN LOOKED AT FOR A MONTH NOW AND THE MECHANIC CAN'T FIGURE IT OUT! PLEASE HELP ME.

Answer:
Hello and welcome. First i would need to know if the transmission in your Aurora was rebuilt to repair this code or was it rebuilt for another reason- and now the code and shifting hard are occurring. Is this the original problem or did the mechanic cause a new condition with the transmission? I will wait for your reply. No, a vacuum leak at the intake manifold or anywhere else on the engine will not cause the shifting problem you are having. That would cause a rough or unstable idle as well as a check engine light with lean codes.

oldsmobile aurora

1998 Chevy Tahoe codes p1870. Checked the computer codes. Transmission slipping. Checked fluid, full, and clean (red). I believe the fluid psi solenoid is bad.
Question = normally the vehicle runs fine. Then when put under a load or driven hard (highway), the engine light comes on and the transmission shifts funny. When the trans acts up, the 1-2 shift is very harsh, and a burning smell is present.

Upon sitting parked for around 1 hour and letting the car cool down the transmission is fine until you drive and apply heavy throttle and torque to it again. I will be changing the filter and fluid tomorrow just to try something but would like your opinion on this problem.

Answer:
P1870 is -component slipping. This can be caused by a problem in the valve body but with that many miles on Your truck it may just be time for an overhaul because of slipping components. As for the condition of the fluid being burnt, that means transmission needs to come apart and the mechanic will look for a failure. Again, with that many miles it is probably just worn out. Try the filter and fluid change to see if it helps. The hard shifts are most likely caused by the line pressure being raised to compensate for a slipping component. This system is adaptive. Meaning that if there is a problem of slipping then the line presure is raised to try correct the condition and keep the car shifting. That adaptive feature can only do so much.


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