Pontiac Repair: knocking under acceleration, crank shaft, sensor positions

Question
QUESTION: 1998 sunfire gt, 2.4, 4 spd auto. code po342 circuit low input.  already replaced cam and crank sensors.  still getting this code. engine knocks under acceleration and low power. hooked up to dcv meter to cmp ground(b) and cmp sensor signal(a) reads 10.5 on target with cam.  also reads 10.5 throughout full manual rotation with breaker bar at harmonic bal. bolt.  what's wrong and how do i fix it.  i rebuilt the motor 3 weeks ago and was running great,  turned it off, has knocked since and shows the code po342.  thx for your help.

ANSWER: Hey Gene:

fist off what kind of knocking noise? Pinging or like a metalic knocking noise? You said you rebuilt the engine? did you replace the crank shaft in this car? the engine may be out od time? the timing chain may be off a tooth or 2. if the timing is out you could get a 342 code. if the crank was replaced you need to do what is called a crankshaft corolation relearn. This is done with a GM scan tool it makes the engine computer learn the crank and cam sensor positions. If that wasn't done it can set codes as well. I'm concerned about the noise you are talking about.....

---------- FOLLOW-UP ----------

QUESTION: first, thx for the reply todd.  crank is original as are cams.   the head is new as well as oil and water pump and new timing chain and all gears and tensioner. no oil burning, was running perfect the night before. son started it the next morning-knocks under acceleration and slightly while idling.  u think the balance shafts have slipped out of time?  once again, has been running great for 3 weeks. new cam and crank sensors and new ignition components as well. i even pulled the timing cover and it's in perfect time. i'll leave you alone after this.  thx for your help. gene.

Answer
If the timing chain is right dead on and the chain didn't jump time. How about the shoes that the chain rides on? the one on the top between the 2 cams has a tendency to break. if all is well there then it is possable that the chain on the oil pump/balance shafts in the pan could have loosened up. that runs at half speed of the crank shaft so the noise shoudl sound like 1/2 the speed of the engine. none of this explains the crank/cam codes though. are all the gound wires attached? or did one of the ground wires loosen up on the transmission mounts of the one big one on the block near the oil filter? if they loosened up or if they have bad connection that can cause all kinds of issues.... good luck :}