Transmission slips. Not at first

Tiny
GT_3800
  • MEMBER
  • 1999 PONTIAC GRAND PRIX
  • 151,000 MILES
I have a 1999 Pontiac Grand Prix GT. It has over 151k miles on it. The problem that I am having is that my transmission slips into gears the longer I drive it?

What I mean is when I drive my car everyday to go to work; at first it wont slip into gear. It will do it after being in a traffic jam, or driving long distances. I can go to work, and it will be slipping by the time I get their, but when I head for lunch it will run like it did when I first start it ever morning. This repeats every time I drive?

Have any idea what could be wrong with my transmission
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Thursday, July 21st, 2011 AT 1:21 AM

33 Replies

Tiny
SATURNTECH9
  • EXPERT
Which engine do you have in your car the size?Also do you any codes in you computer?
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+1
Thursday, July 21st, 2011 AT 1:28 AM
Tiny
GT_3800
  • MEMBER
V6 3800 Series II. Check engine light is not on. No Diagnostic test
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Thursday, July 21st, 2011 AT 3:48 AM
Tiny
SATURNTECH9
  • EXPERT
Usually when the transmission slips it will set a code in the computer. So they told you since the check engine light wasnt on that they wouldnt check forcodes?Will they let you rent a scanner from auto zone to check for codes yourself?Thetwo main reasons transmissions slip is too low of line pressure inside the transmission or a leaking clutch pack piston inside the transmission.
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Thursday, July 21st, 2011 AT 4:17 PM
Tiny
GT_3800
  • MEMBER
I got a code P1811
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Thursday, July 21st, 2011 AT 6:19 PM
Tiny
SATURNTECH9
  • EXPERT
Ok now were getting somewhere that is saying its taking longer to shift then .65 seconds and the computer cannot shorten that time so it sets that code. If you keep driving it like that for too long then it will destroy the transmission.I would say its most likely you have a bad pressure control solenoid in the valve body in the transmission. But you would have to do some tests like a line pressure and control test on the transmission. Also need a scan tool with the correct sofware to do that super expensive and also need a transmission pressure gauge as well. You would also use that scan tool to look at the shift times between 1st to 2nd etc to follow the different steps on the trouble tree. Its best to take it in to a good transmission shop its not going to be a do it yourselfer on the diagnose part anyways the tools are expensive.
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Thursday, July 21st, 2011 AT 6:51 PM
Tiny
GT_3800
  • MEMBER
Could it also deal with relays, or low fluid?
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Thursday, July 21st, 2011 AT 7:15 PM
Tiny
GT_3800
  • MEMBER
Would it be cheaper just to replace it?
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Thursday, July 21st, 2011 AT 7:17 PM
Tiny
SATURNTECH9
  • EXPERT
Its not a relay its most likely a bad pressure control solenoind but without proper testing that would be a guess. As far as the fluid level you can check that I doubt its that though. As far as a replace verus a repair if they found a good amount of metal in your transmission pan then I would say yes. If itd just the solenoid then I would say no.
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Thursday, July 21st, 2011 AT 7:21 PM
Tiny
GT_3800
  • MEMBER
How much would this cost me for the tests (ballpark figure)?
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Thursday, July 21st, 2011 AT 7:51 PM
Tiny
SATURNTECH9
  • EXPERT
I would say 2hrs labor times shop labor rate I dont that it varies from city state etc.
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Thursday, July 21st, 2011 AT 8:23 PM
Tiny
GT_3800
  • MEMBER
How mush would it cost for you?
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Thursday, July 21st, 2011 AT 8:53 PM
Tiny
SATURNTECH9
  • EXPERT
Again it all depends on what shop etc I would say 80-100 per shop labor hr so 160-200 for 2hrs labor.
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Thursday, July 21st, 2011 AT 8:56 PM
Tiny
GT_3800
  • MEMBER
Ok. Thanks you.
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Thursday, July 21st, 2011 AT 9:09 PM
Tiny
SATURNTECH9
  • EXPERT
Your welcome keep me posted on what they find.
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Thursday, July 21st, 2011 AT 9:21 PM
Tiny
GT_3800
  • MEMBER
I have one more question. I check my fluids yesterday. It was really low. I put some in there. Today (12 hours later) I drove it. It ran with no slips, or hard shifting. The only thing was that the RPM's whent higher than normal once on the way to work. Should I still get the test done or drive it for the weekend, and see how it does?
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Friday, July 22nd, 2011 AT 12:48 PM
Tiny
SATURNTECH9
  • EXPERT
How low was it?Was there any visable leaks?If its shifting good now I would have the code p1811 cleared and see how it shifts and if the code comes back and go from there.
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Friday, July 22nd, 2011 AT 5:34 PM
Tiny
GT_3800
  • MEMBER
I will check for leaks, and reset the code, and tell you what happens.
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Friday, July 22nd, 2011 AT 6:22 PM
Tiny
GT_3800
  • MEMBER
It was below the first whole.
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Friday, July 22nd, 2011 AT 6:29 PM
Tiny
SATURNTECH9
  • EXPERT
How many quarts did you add?
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Friday, July 22nd, 2011 AT 7:02 PM
Tiny
GT_3800
  • MEMBER
About 1 quart
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Friday, July 22nd, 2011 AT 7:40 PM

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