feels like trans or front end jumps shifting gears & after releasing accelerator

[FlaminWhite97GTP]

Hello eveyone on the Grand Prix forum, Newb to this site. I had a question about my 1997 Grand Prix GTP that I just picked up today. When me & my dad was driving home & got on the expressway we noticed as we got about 55-60mph we felt a mild jerk & when we went to about 75-80 it felt like the car was engine braking/downshifting & jerking, and my boost guage was surging & my dad was barely stepping on the gas. I don't know what it was because when we were driving in the city it was fine, shifted very smooth & when I got home the trans fluid was was light pinkish-red & it wasn't burnt (trans fluid had about 1000 miles on it). The SES light is on, but it from the o2 sensor going bad & the ABS & Check tire pressure light is on because of the wheel sensor. So could anyone give me some advice & is this expensive to fix. Oh & forgot to mention that I was getting 27-32mpg on average coming home. So I don't thing its the TCC, but I could be wrong

Thanks
Don

 

[Trannyman95]

Re: GP jerking at highway speeds (55-80mph)

It sounds like you may have an ignition problem causing a misfire so the first place I would start is to look at the ignition components such as spart plugs, plug wires, and definately check the coil terminals where the spark plug wires connect to as this is a very common area for rust and corrosion. If you have access to a scan tool it will show individual cylinder misfire. If everything checks out good here then I would look at transmission data-pending you have access to a scan tool- and watch TCC apply% and TCC slippage rpm and see what is going on when you feel the bucking, but again I would really lean towards an ignition problem or at least rule it out first.

 

[FlaminWhite97GTP]

Re: GP jerking at highway speeds (55-80mph)

Hello eveyone on the Grand Prix forum, Newb to this site. I had a question about my 1997 Grand Prix GTP that I just picked up today. When me & my dad was driving home & got on the expressway we noticed as we got about 55-60mph we felt a mild jerk & when we went to about 75-80 it felt like the car was engine braking/downshifting & jerking, and my boost guage was surging & my dad was barely stepping on the gas. I don't know what it was because when we were driving in the city it was fine, shifted very smooth & when I got home the trans fluid was was light pinkish-red & it wasn't burnt (trans fluid had about 1000 miles on it). The SES light is on, but it from the o2 sensor going bad & the ABS & Check tire pressure light is on because of the wheel sensor. So could anyone give me some advice & is this expensive to fix. Oh & forgot to mention that I was getting 27-32mpg on average coming home. So I don't thing its the TCC, but I could be wrong

Thanks
Don

 

[FlaminWhite97GTP]

Re: GP jerking at highway speeds (55-80mph)

Thanks for the help. I drove it today a little more & it stopped the highway jerk. But when I'm driving in the city it was like jerking & clunking (it does't pull me forward like a trans slip, but it feels like the engine & trans lifts up & down)after each gear change & when I let off the accelerator too fast. It does it intermittenly, like I drove for like 2 hours in the city & the trans shifted great. Like I said, I don't think it's the TCC because I am averaging 24.5mpg in mostly city driving & 32 on the highway, but I could be wrong. I am going to run the codes tomorrow. I am thinking that it the mounts, because when it's Idling in Park, you can hear a rattling sounds, & when i'm driving I feel the car shaking a little & there is vibration in the steering wheel. I know it's a old car & I know I'm asking alot of question, but I just need is this a major problem

 

[BillBoost37]

Re: feels like trans or front end jumps shifting gears & after releasing accelerator

At that MPG I doubt your O2 is bad. Sounds like it's working great.

Is the code a P0171, if so..it's not likely an O2 sensor.