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Phantom Accelleration, and Hard To Downshift

8

88XJSport

NAXJA Forum User
Location
Michigan
As of late, when I take off from a light, I will let the engine rev to say 2500rpm. While keeping the pedal in the same spot, the revs will smoothly go up, like normal, but then it will jump very fast (pedal didn't move) to around 3200 and then shift to second. This happens at all speeds, while smoothly accellerating, the revs will rise themselves. And no, it is NOT downshifting, the pedal is in the same spot.


I also have a problem with down shifting. I almost have to press the pedal to the floor, then it will finally realize I need to down shift (to pass traffic) and it will down shift, revs will go too high very quickly, 4000rpm. Of course this is too high, just to pass traffic, or increase speed.

Are these two problems related? How can I fix this. It just started to happen recently.

TPS is 5 months old.
 
So when I press the skinny pedal, hold it, and it will act like I pressed the pedal a little bit more, sounds like a TPS?

Ill check it anyway.
 
you need to rule out possibilities. tps does control the tranny depending on throttle position.

also check for vacuum leaks. how does it idle? may want to check throttle linkage for binding

i believe there is also a TV cable that control downshifting.
 
could it be slippage. though u wouldnt think that would cause the downshifting issue. it might, im no tech
 
Maybe check tranny fluid level too.
 
I am assuming it is an 88 from your user name. With power off, disconnect the TPS connectors, and check the ground connections on both TPS wiring harness side, connectors to the battery negative post, both should read a steady reading of less then 1 ohm. If it is higher, or if it jumps when you wigle the wiring harness anywhere, then you need to run a new ground wire from the TPS wiring harness connector (cut an splice in a new ground wire) directly to the battery negaive post clamp. Also check the connectors themselves, they can get old, week and ditry and imitate a bad tps with poor continuity at the connectors.

If the TPS got wet, it may be bad already, if not it is likely a ground wire connection problem, been there done that!!!!!!!
 
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