my car recently developed this problem.
the rpm needle bounces and shakes now. i don't know why. usually when i drive 70 on the highway, it reads 2k rpms. however, its reading 2300 rpms instead , and is shaking around. what could be the cause of this? even at idle, it shakes from 500 to 700 rpms. how can i fix this wacky rpm needle?
thanks.

p.s. lg4, auto, 2.73's

 

TPS. Check out the tech article on adjusting them! Either that or you've got a tiny vacuum leak.

 

where is the article on the TPS? what is TPS? also, coudl someone show me where the leak is coming from?

 

One time when I forgot to hook up a spark plug wire, the arcing caused the tach to jump (without the engine RPMs actually changing). Check for a bad plug wire.

It's just the tach bouncing, not the engine speed, right?

 

https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

TPS = Throttle Position Sensor

It tells the ECM where the RPM is (basically) and from there the ECM figures out if it needs to add more fuel, or lean it out or what be it.

As for a vacuum leak, you just have to make sure that all of your vacuum hoses are connected, and not corroded. You may wish to do a few in order to expand your knowledge on both

 

that's correct, the engine speed is not increasing, but the tach is bouncing.... i'll check the spark plug wires. any other ideas on what it could be?