transmission problems

hi everyone
i own a 2001 grand prix gt,need help,
the tranny is shifting little bit hard,but it only sometimes not all the time the car is running,i soones i start driving the shifting is smooth and nice and after few miles it start shifting hard and if i stop and set in parking for a minute,and continue driving it start shifting smooth again,
anyone with some info on this i will be so thankfuiam hoping it will be some sensor!

If certain transmission codes are set, it causes the PCM to command full line pressure, which will cause a hard shift...some codes do not turn on a CE light, until the test fails on two consecutive "trips"....

Need to have codes in PCM read....

When was the last time you changed the transmission fluid and filter? If it hasn't been serviced in a long time that would be a good start.

Oscar.

hi oscar
i did change the transmission fluid and filter,thinking that i was the problem,but still doing the samething,is just weird,because i can be driving for awhile and start shifting hard and i stop in a red light,and continue after green and start shifting smooth with no problems,it come and goes,and is been doing that since i got the car 3 months ago and never show me any engine light or nothing?

How is the engine performing?

The PCM relies on different engine sensors to control the transmission behavior too. Are you having any DTC's? Do you have access to a live data capable scanner?

Oscar.

yep the engine performing is good no issue on that,and no i dont have any way to hook it up to a scanner,unless i take it to a tranny shop and pay about $75 dollards,i dont know if autozone scanner will pick it up the codes for this specific issue?
and what's is a DTC?lol sorry dont know to much about this

I see,

DTC stands for Diagnostic Trouble Code, the ones you pull with a scanner ;).

I asked about the live data scanner in order to get the actual readings from some of the engine sensors, that way you could find out if you have any engine problems that you haven't noticed. The autozone scanner should be able (sometimes not possible) to access common transmission problems. It wouldn't be a bad idea to see if you have any pending DTC's which don't trip the Check Engine Light (CEL).

I'm not very knowledgeable with transmission problems, maybe you should wait a little and see if other users have any opinions or just bite the bullet and pay the $75 to have it properly diagnosed instead of just throwing random parts at it to see if it fixes the problem.

As a final note, did you replace the entire transmission fluid (torque converter drained) or only did a pan drop?

Oscar.

i only did the pan drop,and i will take it to autozone ,and see if they scanner will pick any code,thanks for all your help!
and i just realize your are from irapuato,mex.
nice iam from nuevo leon,mex.

Paisano!! ;) Good to have a country fellow around here.

The pan drop method is a good start but unfortunately it doesn't replaces the entire fluid; it takes only about half of the actual capacity in the transmission. Which might still be the cause of your problem. According to my manual the pan drop drains 7 qts out of 13.4 qts in total from the transmission.

Shops can do a fluid exchange for you, however some users don't recommend it because they sometimes use too much back pressure which can do more harm than good to the transmission internals.

The other method is to do it yourself through the cooler lines. You need to disconnect one of the lines from the radiator (I think it's the lower one) and add a piece of hose so you can direct the fluid into an appropiate container.

Start and idle the engine until you see the fluid flow seems erratic (pump starts cavitating and shouldn't take more than a couple of minutes), immediatly shut off the car (better to have an assistant). Measure the amount of fluid so you know how much to refill. Repeat the process until you have used about 13.4 qts.

As a reference the amount of fluid pumped should be around 2 qts. in 30 seconds. You might want to use previously marked (at each qt.) milk jugs so it's easier to know how much fluid is being pumped.

It's an easy but tedious task and your choice to either do it or not. At this point you might want to focus on diagnosing it first so you don't spend money on repairs you might not need, however keeping the fluid in good condition is a MUST to ensure a longer life of the transmission.

Oscar.

Checkout the thread at link below for 4T65E autotransaxle hard shift/P1811 issues.

http://www.automotiveforums.com/vbulletin/showthread.php?t=899929