I just changed the upper timing chain guide on my 12v vr6. after almost was all said and done the rear cam shaft sprocket slipped just a tooth (i think) as my brother put his weight on it. Instead of taking off the tranny and all that I unbolted the cam shaft and put it back on the correct timing. I then manually turned the motor over 3 times and brought it back to tdc. All the timing marks lined up and I finished up the job. I then drove the car daily for two weeks, and now it is throwing the P0340 code on an obd2 scanner which is the code for a misfire and timing/blah blah..I cleared the code but it comes back.. the motor sounds good idles and runs smooth all the way to top end.. no noise or performance loss...Id think if the cam was off ud be able to hear choking or some noise...anyone have any input?