I have a 98 Mazda 626 GF 2L with a 2 pin camshaft position sensor.
I hooked up to the ecu to monitor it and was wondering how often it should be switching from Low to High.
The scan tool is returning a data sample approximately every 75 milliseconds ( I was logging 6 pid's ) and it was almost always returning low. Very rarely it would show a burst of high readings for about 450 milliseconds.
On a dohc engine I'm assuming the cam rotates at half the crank speed, so if it's idling at 600 rpm lets say then the cam will rotate 4 or 5 times per second. So if the crank has say 34 teeth and the cam gear 68 then a tooth would pass about 340 times per second or every 3 milliseconds?
So the signal would switch every 3ms?
The thing is there is no DTC code relating to the camshaft sensor.
Should I try logging again with just the one pid to try and get more frequent data samples? Or is my only option to backprobe the wire with an oscilloscope?
So I took off the valve cover, and apparently the cam sensor reads a bump on the camshaft gear:
OK, so at 600 rpm idle and camshaft running half speed, I should see the bump go by on a scan tool or oscilloscope about 5 times per second - i.e. the signal should go high about every 200 milliseconds? So even if I'm getting a data sample every 75ms I should see it with no problem I think.