Anyone that has a tachometer gauge acting strange and showing unusually high RPM speeds and bouncing. Make sure the tone wheel on the crank is clean and no grease and grime in the tone wheel. Then make sure ther sensor is in good condition and the gap is correct. 

 

After I got the truck fired up it had a very wild tach and jumped all over the gauge randomly. After I power washed the engine 99% of that went away. Now showing correct numbers and no longer jumping wild high numbers like banging 4.5k randomly. 

More than likely its a bad gauge cluster that the 06's are known for. The main thing that fails is the tach. 

 

You should get a CEL if the rpms vary between the CPS and Cam sensor. 

Edited April 26, 20214 yr by AH64ID

Actually its a bad crank sensor. Finally tossed a code couple days ago and refused to start. Thankfully I've got my new sensor sitting in the front seat.

Another issue fixed..  bad crank sensor.

Finalized the install of the sensor its held in with a Allen screw. It's kind of hard to spot with crap ton of dirt and grease. Verified the tach signal against a live data tool its about -100 behind the tach on the dash but not bad. Reset the two codes for crank sensor performance and Crank Sensor A circuit issue. Sorry I didn't keep the error codes...