Overdrive works.. sometimes...

[maroon111993]

97 Grand Prix GTP.. So, in the morning around 6am when I go to work, the car will never kick into overdrive. When I come home at 4:30, it goes in no problem. But when it won't go into overdrive on its own, if I mash the gas and let off real quick, it will shift into overdrive. But I have to do this every time I want it to go into overdrive. Also, when I have my cruise set at 70, and it IS in overdrive.. when I hold the Coast button or step on the brake to disengage cruise, it will stay in gear for about 5 seconds and then start slowing down.

I have a friend who seems to think it's a vacuum issue? Don't know if 97s have a vacuum-controlled overdrive.. Any ideas?

I did check the vacuum lines on the supercharger (they are larger now than stock) and a couple were loose on the 'pegs' they slide onto.. one of them went back to the firewall, and around the fuse box and then looked like it went down below the engine (maybe to transmission?) I tightened them all but haven't tested it out yet, because it seems to only stay in 3rd when it's cold in the mornings.

Also, just regular city driving it'll want to stay in first forever and rev at 4k for awhile before shifting, and when I got on it and was going about 90, it redlined in 3rd and wouldn't shift until I let off the gas, THEN it went into 4th.

ANOTHER thing... SOMETIMES in the mornings it will act like it's a manual with the clutch only half engaged.. I can get on it and it doesn't 'slip' by any means... just feels way underpowered like it doesn't want to go.. But when I move the shifter down into 1st, it accelerates fine.

Any ideas with any of these issues please let me know. I've already checked my transmission fluid and it's fine.. had a little grayish in the bottom of the pan when I changed the filter to do my shift kit a few months back.. but nothing alarming.

[MattStrike]

Sounds like a seal in the trans is leaking a little. Putting it into 1st bumps the line pressure up. Have you tried the Lucas trans fix yet?

[maroon111993]

I had it in when I did my first filter change before the shift kit. Might have to try some now too. It came with all new seals and everything though.. Guess it's worth a shot

[KnightBonne02]

So what did the issue end up being