From what I have learned, yes it can cause a rough idle. It has to be forced relearn with a capable scan tool. This happens anytime you move or remove the crank position sensor. It sets the retard correctly. Unlike the older simpler times when we could use a timing light. I am going to have to do it when I get my engine back in and I intend on doing it at the GM dealer (I don't have faith in my local shops). I have read that prior to doing the re-learn your vehicle might run pretty well, or it might run rough, however, it is not right until the scan tool forces the re-learn.

 

i have an appt w/ a guy here who i have dealt w/ for almost 10 years so he can scan the puter ad reset the cam/crank sensors and hopefully end all this madness so i can smog it and just drive it. i will post any/all findings as well as results upon completion. i really appreciate the time you and the others have spent reading and dropping ideas on this delima i have been having!!

 

ok, the pile of crap (a.k.a. the 4.3 motor) strikes again. i took it to get diagnosed and he "determined" that the timing was 60 before TDC. nothing else but the p0340 camshaft position sensor curcuit code. they dont work on cars but told me a tooth or 2 off on the distributer. took it home and one-by-one moved the tooth (being careful to mark and right down each and every move i made) moved the distributer one tooth forward, then 2 teeth forward, then 3 teeth forward and so on until i made a 360 degree circle through all 13 teeth with no results. after a full rotation of the distributer i thought maybe the timing chain jumped (what the hell else could it be) so i removed the timing chain cover and aligned the marks and it hadnt changed/jumped. i replaced the timing chain and gears anyway (since i had it apart). tried aligning the 2 marks on the harmonic balancer, getting the #1 cyl at TDC and aligning the dizzy w. the #6 on the dizzy base and nothing once again. it wont run at all now, back to that crap. today (13th day playing w/ the timing issue) im going to attempt to set the timing once again but i cant for the life of me get the alignment marks on balancer, $1 TDC and dizzy pointing at #6 mark.