[Northstar97hell]

I just purchased this 97 DeVille, was running fine, January 2014 had head casket repair. Now showing P0340 code. Replaced CMP sensor, still rough on idle. Took to local shop and they are telling me that it is the timing and you have to spend 12 hours just to get timing right. Does this sound right? Should I replace CKP sensors first? Help, I can't afford to spend much on this.

 

[rodnok01]

Wrong forum, a mod will move.
Post the code with definition please.
A rough idle can be a TB needing cleaned or vacuum leak. As for timing being off it is possible they dorked the repair work up. I'd do a lot of other things before digging into timing.
And of course welcome to CF.

 

[Ranger]

:welcome:

Since the motor was apart, it's hard to pin point it, but if it was valve timing, it would have been that way right from the git go. Was it or did it just start?

CKP sensors don't usually cause a rough idle. They tend to cause a stall.

I'm with Rod, clean the TB and rule out vacuum leaks.