• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

Jumping/Fluctuating RPMs

B

birdgm

New member
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
 


mine's doing the same thing, on ramps and some hills. i'm assuming the transmission's going. was it a new or used transmission? i know you said new, but i'm just making sure. this started happening with mine around 135k. i usually just let off the throttle and then gun it so it downshifts.

one way i think about it is that i'm like confusing the transmission. like, it gets to the shift point, and lets the clutch out, but once that happens the rpm's get high enough to put it back into the same gear. and then the rpm's go back down to the shift point, and so on... sorry if that's confusing, it's just what i hope is happening so i don't need a new transmission
 
the torque converter is locking/unlocking and its never going into full lockup. it might be the transmission or the pressure solenoid.
 
hoping that it's not the transmission, is there an easy/cheap way to fix the pressure solenoid? i know absolutely nothing about transmissions...
 
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
 
sounds legit to me. mine has also stopped slipping because i kiss it goodnight when i get off work. seriously. hasn't in like 2 weeks.

it does make sense though. if something happens and the pressure drops, you could have sporadic shifts
 
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!
 


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.
 
You must log in or register to reply here.
Back
Top