I Was driving the other day and everything started to go crazy! first thing i noticed was the Tach going crazy over 3krpm then the check engine light came on. On closer inspection it threw all those codes. (plus a torque converter clutch code which disappeared. Anyone had a similar issue? I'm guessing that everything didn't decide to go at once... and that I have a gremlin somewhere. Any help would be greatly appreciated. Thanks.

 

Look in the Codes section & think of what they may have in common. Something like a faulty ground wire to a fuse box could fubar a number of things all at once. When you were driving did you hit a springtime pot hole or a large puddle at decent speed? Just trying to think of what was going on when things went haywire may help.
A tach jumping around could be the crankshaft position sensor - but usually thats only if the engine has had really high revs or a bad knock etc. <--- personal experience on that one

 

Sorry for the late response things got crazy and had to focus on other things. No it was a progressive thing when it started happening. The first time I started noticing it was when i was bringing my father for a appointment 50 miles away and it started doing it around 4-5k ( was going up hill and passing on the highway) then it started to become more frequent to the point now and has been anything over 3k rpms it starts spazing. It was dry and i'm guessing around 70 degrees. Wasn't doing any work on my car at the time either. I replaced the crankshaft position sensor to no avail ( seems slightly better but is still doing it) and there is no kocking going on with my engine. Thanks - Mark

 

Did you do a CKP relearn procedure?
Install the scan tool.
Apply the vehicle's parking brake.
Block the drive wheels.
Close the hood.
Place the vehicle's transmission in Park (AT) or Neutral (MT) .
Idle the engine until the coolant temperature reaches 65°C (150°F) .
Turn OFF all the accessories. IMPORTANT : If the CKP System Variation Learn Procedure cannot be completed successfully, refer to DTC P1336 Crankshaft Position (CKP) System Variation Not Learned for additional diagnostic information.
Enable the Crankshaft Position System Variation Learn Procedure with the scan tool. IMPORTANT : After the ignition switch is turned to the CRANK position, the VCM must see a change in the state of brake switch (Released to Applied) to run the learn procedure. Also, the service brakes, not the parking brake, must be held throughout the duration of the learn procedure.
Apply and hold the service brakes. IMPORTANT : While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine will respond to throttle position after the learn procedure is complete.
Slowly raise the engine speed to 4000 RPM .
Immediately release the Throttle when the engine speed decreases.
Turn OFF the ignition for 15 seconds after the learn procedure is completed successfully.
If it still has an erratic tach you kay need a CKP spacer GM part number 12565102.
I also checked the dist. cap, it was off a little bit.