Steve98Z

For everyone who hasn't read the old thread about my cam sensor problems here is a brief summary of what has happened. I went to start my car, it was hard to start and the SES light came on. P0343 cam position sensor high output, I replaced the sensor and the code remained and the car was still hard to start. Took it to the dealer and they gave me the run around and said my PCM must be bad.

After talking with several people one name kept coming up who they were sure he could fix my car. It has been at his shop for three days and he and I both are puzzled. The PCM is fine and so is all the wiring. With the cam position sensor out of the car and you car wave a metal object back in forth in front of it and the computer sees the signal. That rules out the sensor, wiring, and the PCM. The problem is when you put that same sensor back in the car it picks up nothing (shows a flatline on his scope). With a mirror and a flashlight you can look down inside where the cam sensor sits and see the reluctor ring on the cam and it is not damaged. What is going on and what do I (him) need to check next? Everything works during the simulation but you put it in the car and get nothing. Somebody give me some direction here

Pro Stock John

iTrader: (34)

Is the cam sensor a hall effect sensor? If the camshaft has major endplay could that cause the trigger wheel to go out of range for the sensor?

Steve98Z

Yes the cam sensor is a hall effect switch, as far as end play in the cam I don't know, it only has a few thousand miles on it

Pro Stock John

iTrader: (34)

What mods do you have? What did you change, if anything, before this problem popped up?

If the sensor can't see the trigger portion on the cam it might be clipping out. When was the cam changed?

Steve98Z

I haven't done anymods lately, all of the mods were done at once a few months back including the cam. I talked with Sean Freese a few minutes ago and he said the only thing he could think of is that if the cam plate bolts backed out and the cam walked forward this would cause my problems. Really thats the only thing that makes sense right now because all the wiring and grounds tested good, so did the PCM and we have tried three different sensors.

C4VetteLS1

Id guess cam plate bolts as well

Steve98Z

I just got back from the shop where my car is and guess what the cam has walked! Whats weird id, it didn't come forward it walked backward about a quarter inch. The lifers are so far forward on the lobes that an area about the thickness of two sheets of paper of the roller lifters are not even touching the lobes. It would make sense if the cam plate bolts loosened the cam could walk forward, but how in the hell did it walk backwards?

Pro Stock John

iTrader: (34)

That's what I thought was happening.

Terry Burger

iTrader: (4)

I have an extra set of '98 sensors (all the same I think?) for sale if you think it might be the sensor.