Thread: 1998 gtp wont drive in 4th NO SLIPPING THO

Hi im ben from michigan. i just bought a 1998 gtp and it needs some tlc. heres the problems. it gets an average of 15 mpg driving around and smells like fuel at exhaust at an idle and also has a roughf idle. When i drive the car it will NOT stay in drive (4th gear) it shifts fine 1st to second and second to third and if you let off the gas it upshifts up into drive (4th gear) but as soon as you give it gas it goes back into 3rd gear. reminds me of a 700r4 i had in a camaro and the tv cable (kick down cable) was messed up. it only get about 15-16 mpd on the display. i just bought this car a couple days ago and drove it home about 150 miles and didnt even notice the trans problem we where never on the highway tho and it drives nice. very driveable with 1 2 3 gear as surprising as it sounds. the other problem is the supercharger when it would hit boost on the gadge on dash it would cut out the motor, like miss real bad so i took the belt for the super charger off and all that went away runs great just smells like unburnt fuel at exhaust and idle miss and poor miles pere gallon (15) any idea's?????? any info would be great. also the cars check engine light dont work AT ALL. lol iv checked it when you turn ke on and all others things to get it to come on and it wont, i can see it in the dash it just wont light up. weird as heck. but i got the car cheap and man is it awsome nice leather great audio very comfterble and the car drives itself. I love it. well anyway thanks for any imput you guys have and i will get this figured out and post all changes unlike other people who get the car fixed working great and never come back to post what did the trick.... thanks again

guys im not sure forth is out. it does not rev up in fourth like a slipping gear. it only goes into 4th if you let off the gas it goes into 4th gear but as soon as you go to give it gas it drops back into 3rd gear. is there somthing that locks 4th gear in? it does not at like fourt is gone it just wont stay in fourth gear. unless the computer knows it gone and thats why it wont stay in 4th and goes back to 3rd the instant you tuch the gas pedal. its not like its reving in 4th it only drops in 4th when you let off the gas but instantly goes back to 3rd when you touch the gas peddal.

today i put new plugs in allong with new air cleaner. took all sensors out even the egr and sprayed them out with carb cleaner. after the tune up i threw the super charger belt back on and took it out for a spin and she runs great 100% better engine is very very peppy and no missing at all. this thing hauls balls too as for the trans it still not using 4th gear. it falls into 4th if your going 50 + and let off the gas it goeas right into 4th but the instant you touch the gas peddal it puts the trans back into 3rd!!!!! funny thing is that the car dont mind it and i never even noticed anything at all while driving just was concernd about the bad gas milage it was showing on the dash around 14mpg and i think the car runs rich at idle. but anyway the car does not act like a clutch slipping or anything at all ever. no weird noises nothing. car shifts great 1 2 3 and fun as he.l for a cheap beater heads up dis leather seats awsome audio tons of power. anyway thanks and please any info into the tras would be great

please any info into the tras would be great

4th is GONE. Will never come back. You will be forever driving in 3rd on the highway. Save up some $$ and get the parts Bill suggested and fix it yourself, or a rebuilt one from TEP and swap it in. It'll far outlast any stock one, even if its a "rebuilt" one from another place.

If you don't want to attempt the hard parts install then maybe find a low mileage unit from a 98-02 GTP (must be a GTP as a GT trans has a different gear ratio) and swap it in and drive that one until it strips the 4th clutch hub again like you have now.

The only downside to the OD being gone is less mileage (as you've noticed). It will be turning higher rpms than w/ OD. May cause a bit more heat too, but not to the point of burning the rest up assuming the fluid/filter has been changed recently.

When you swap in another trans. may want to think about installing an aux. cooler as well to help keeps temps down.

Also, did you clean the MAF while you were cleaning everything else? That may help get another mile or 2 per gallon.

ok so today i noticed when im cruzing and it goes into drive 4th gear and i tap the brakes it does not drop into 3rd gear. i had a buddy with a camaro with the 3.8 and it was doing the same thing as my grand prix. he took it to the shop and come to find out that he just had a bad switch. adjusted the brake somthing and he has had drive ever sence. could i have somthing like that happing?

ok this will answer alot of questions for me. if fourth gear was gone would the computer tell it to go back to 3rd? like iv said when i let off the gas completely it will go into 4th but the instant i touch the gas peddal it goes back to 3rd gear. it never lets the engine race like the gear is stripped. and when im in 4th gear (giving no gas) and i tap the breaks it does not drop back into 3rd gear like it should.

Also my shift lock does not work. you gota jam a key or pencil in the hole to be able to get outa park. anyone know how to fix this?

ok im having a problem with my 98 gtp. it will go into 4th gear (drive) if i let of the gas but the instant i touch the gas peddal it goes back to 3rd gear. also if im cruzing and let off the gas and it goes into 4th (drive) and tap the brakes it does not drop into 3rd like it should. could something be outa alingment? i know a buddy had a camaro with the 3.8 and auto trans and his would not go into 4th gear and it ended up being something to do with his brake peddal sylinod or something like that. was an easy fix and he has had 4th gear ever sence. any advice would be great. im also having a problem with the shifter lock- i have a pen i stick in the hole to get shifter to unlock. any easy fixes???? thanks guys and i willpost results of anything i try.

When you are cruising in 4th and tap the brakes it should unlock the TC, but not sure if it drops you out of 4th as well. Never tried it on mine.

You may not see a huge rpm flair when it tries to go to 4th and cannot thus dropping back into 3rd, but its there. The ECM may be taking care of this for you. When stripped it will not just wildly rev into where 4th should be, hence it drops it back to 3rd. I'd be willing to bet that when you give it gas and it drops out of OD, and while it is like this you move the shifter from "D" to "3" that you will not see any difference in cruising RPM's. That's exactly what I saw when I lost OD. You symptoms exactly.

And here is a link that may shed some light on your shifter issue...

http://www.grandprixforums.net/stuck...ork-13995.html

NO in my car when you cruzin along it will never shift to 4th gear you Must let off the gas and rpms will drop way down you go to give it gas and its back to third gear. if you have it in drive it only shifts into 3rd untell you tottaly let off the gas then it goes into 4th gear and if you downshift it goes back to 3rd gear just like it would if you gave it gas. It does Not "wildly rev into where 4th should be, hence it drops it back to 3rd" and also my shift lock dont work. it should un lock with car started foot on brake peddal. thats why i think my problem may lie int he brake scitches or some crap. My Car Never slips in 4th its never even givin the opertunity! what i need to know.. Does anyone have a grand prix they can get cruzin in 4th (drive) gear and tap the brakes and see if it downshifts please as far as i know it should.

"1998 grand prix gtp" the car has never slipped or reved up or made any weird noise in drive (4th gear) its never had the opertunity seems like something is preventing 4th gear (drive) from being driven in. Its avoiding the car being driven in 4th is the problem

I think the thing that tell the trans to downshift from drive when you touch the brake is messed up and not letting the car be driven in 4ht gear (drive) lets say im cruzin down the road 55mph and i shift into drive and let off the gas it drops rpms and goes into drive. if i then downshift the rps jump up just like drping a gear and you can feel it. same thing if i was driven 55mph in drive and let off the gas it will upshift into drive but the second i touch the gas it goes right back into 3rd instantly and its even hard to notice at all that it does this. when i bought the car i drove home over 100 miles and never even noticed anything wrong! it dont make any noises dont act at all like a slipping transmission ever! and also i should add that my shift lock is not working and that also works off sensors off the brake peddal. just like the downshift of trans when in 4th gear (drive) and tap the brakes ( it downshifts) and im thinking this MAY have somthing to do with why my car is never given the opertounity to slip or be driven in 4th gear! and if i was right what an awsome post this would be an a huge help to the grand prix comunity as i will post results of anything that helps even if i do end up tearing the trans apart. thanks everyone