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3rd to 4th transmision issues

Hamnjelly

New member
I have a 1998 grand prix gtp w/ 120k miles. The other day I was flooring it, when I reached 90 mph it wouldnt shift into 4th gear, so I let off on the pedal and pushed back on and it finnaly shifted. It has done this before, and it just wont shift for some reasob. Any ideas?
 


What maintenance have you done on the tranny? Ever change the fluid and filter? Check the fluid level or condition?
 


wide open throttle. So if you just keep it hammered in second it just keeps climing? What rpm do you end up letting off.
 
wide open throttle. So if you just keep it hammered in second it just keeps climing? What rpm do you end up letting off.

I wot threw 1-2-3, when I reach 3rd it just keeps reving at 6k rpm, stays at 6k and wont shift up unless I completely let up and the push down again. I only have this problem when wot it. My forth gear shifts normal, but for some reason im getting terrible gas millage even when I drive slow.
 
so when your WOT, you going over 120??? and then trying to shift into 4th????

1st gear is 45ish
2nd is 85ish
3rd is 125+
then its 4th gear.
at WOT

which is extremely fast.


I think you need to count the shifts to make sure exactly what gear you are having trouble getting into.


Maybe try a tune up and then see what your MPG's end up being at.
 
so when your WOT, you going over 120??? and then trying to shift into 4th????

1st gear is 45ish
2nd is 85ish
3rd is 125+
then its 4th gear.
at WOT

which is extremely fast.


I think you need to count the shifts to make sure exactly what gear you are having trouble getting into.


Maybe try a tune up and then see what your MPG's end up being at.

Maybe it is 2nd, ill have to try it out again.
 
It might be third. Let's say you have a ton of KR and a flashing check engine light etc that you didn't mention. Car can't make the power and if you are in third at 90ish.. the kr etc is probably holding things back.

Something as simple as a dirty MAF, bad TPS can mess with shifts badly. Also KR etc can.

Fuel mileage..your testing wide open runs with no maintenance and saying mileage is bad? Not saying this to be mean, but to open your eyes as to what I'm reading into when you say that.
 


It might be third. Let's say you have a ton of KR and a flashing check engine light etc that you didn't mention. Car can't make the power and if you are in third at 90ish.. the kr etc is probably holding things back.

Something as simple as a dirty MAF, bad TPS can mess with shifts badly. Also KR etc can.

Fuel mileage..your testing wide open runs with no maintenance and saying mileage is bad? Not saying this to be mean, but to open your eyes as to what I'm reading into when you say that.

This is where I was going. If you have a brand new-to-you car with higher miles and take it out to beat on it and see how fast it will go, but something isn't right, maybe you should consider doing some maintenance on it first.

I obviously would change the tranny fluid and filter. But things like plugs and wires can also do like Bill said and not allow the car enough power to shift.

But bottom line I think, if you are going to run your car hard, high RPMs and high MPH, you need to make sure it is in good mechanical condition and the maintenance is up to date. Otherwise, if it doesn't run right, you are just taking a shot in the dark of what it is.
 
I thought our cars wouldn't upshift into OD if at WOT? Either way, not a good idea to let it shift there at that high of RPM.

Would do a tune-up including fuel and air filter. Also, what octane of fuel are you running in it? You should be running 93 in it, or at least 91. Anything less and its a time bomb.

And if not, then this link will help you out shortly so you can replace the chipped pistons- Morad Parts Company - 3800 Motors, Transaxles, & Stock Parts
 
Mine would do the same thing and it wound up being the fourth gear splines on the shaft worn and wouldn't always let it shift out unless you let up off the pedal.
 
i was thinking that too max. when it happened to me i noticed i was doing 65mph at like 3500rpms and when i shifted into 3 from D it didnt downshift.
 


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