Thread: Jumping/Fluctuating RPMs

Hey GP Community,

Quick question for anyone who can help me with a small issue I have with my GP.

I drive a 2000 GTP with 176 K. New transmission installed approx. 2 years ago (previous owner) when the car had 145 K.

Currently the car shifts/drives well, with the exception of one small problem.

As I enter onto the freeway and slowly accelerate (this does not happen with rapid acceleration) the RMPs jump from 1500 K to 2500K. I can also hear the car revving slightly. This happens as I reach 90-100 KMs. If I touch the gas harder, this no longer happens. I also notice this happens if the car is on an incline while again driving quickly.

Any thoughts?

Mike

Hi All,

So an update on this issue. I was able to dig through the paper work and determined what the prev. owner did with the car at 148,000.

Converter, seal kit, 4 claim hub, plumatary gear set, chunnul plate sleeve, filter, oil, bands

So it appears I was incorrect when I said a new transmission was put in. Rather it appears that it was a converter.

The car loves to bounce RPMs when I'm up in the 100-120 KM/H range.

Looks like I'm going to have to get it checked out at a transmission place.

Thanks,

Mike

I have the same exact problem. I have 135k on mine. I am the original owner and never raced it. But I do a lot of hwy driving.

I heard if you get a pcm tune or canned tune it would boost up the hydraulic pressure to the press/solenoid and help eliminate the oscillations. Also the skip shift crap.

Anyone heard the same?

Update:

So today I took my car into a reputable transmission shop near my house. The guy took it for a road test with me and thought that it was the torque converter (as mentioned in this discussion). He took the car for a few hours. He also was having difficulty getting the code scanner to work, and thus began to wonder if this was something electronic. He cleaned the battery and re-set the computer...and lo and behold...the problem went away. The car now runs better then when I first purchased it. According to him he has seen this before...in his words the computer can get confused and sometimes needs "rebooting." Does this make any sense to anyone here? If the problem returns I will make sure to update you guys.

Thanks...Mike

My car develpoed the same problem. I was able to tune it out by adding 5% to the minimum TCC duty cylce. You are also correct about having to "reboot" the computer. This erases any learned, and adapted memory the computer has stored to compensate for "warp and wear". This is especially important to do if the transmission has been completely overhauled, any extra pressure, or shift timing the computer has
adjusted for the old tranny can cause harsh, or erratic shifting.

Thanks for the Update.. I know exactly what to do. I'll get back to y'all when I am done. Mikey!

I did the old trick I use to do when I was restoring '80's era BMW's.

I took the battery cables off and connected them together and then to ground for about an hour. This completely erases or clears the memory the PCM and all associated capacitors throughout the electrical system that may inadvertently restore some parameters.

Reconnected and it worked like a champ. No more 3rd &4th gear oscillations and the car even runs better!

Thanks BirdGM for reminding me of that old trick! Hope yours is running great too!

No problem...glad we could help each other out!

Man!!! What a relief! I was about to replace the tranny too. Saaaaawwweeeeeet!

same problem on my car but i have 100k. only happens in 4th gear and around 47-63 mph when its geared low. so when i give it slight gas to accelerate, the rpms flunctuate up and down rapidly but only is 200rpm intervals (probably twice every second) and then stops once i stop accelerating. it does it so often that i just give it enough gas to shift down into 3rd. my transmission seems fine so idk where to start. my friends gp has the same problem. il try the battery thing and see if it works.

Does your tranny shift smooth at lesser speeds (i.e. 25-40 MPH)?