Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: CBH on 21 October 2010, 13:58:23
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Ok what's the point of cam shaft sensor.
The engine timing comes from the crank shaft sensor.
The crank shaft and the cam shaft will stay timed unless the belt slips, if it breaks and the cam shaft sensor detects the shaft has stopped it won't stop the engine in time
My V6 was running very odd, sometimes it had no power, or it would take an age to start, also got autogear boxes message on the display.
Check the error codes had 127
So swapped the sensor for a spare and all the problems have gone away it's like driving a new car again.
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The camshaft sensor tells the ECU which phase the cams are in relative to the crank. The four strokes of the engine take 2 turns of the crank, so the crank sensor can't tell the ECU which cylinder is firing when.
e.g. When cylinder 1 is at TDC, cylinder 4 will also be at TDC. Which one is starting its' power stroke depends on the position of the cams.
This information is needed because the Omega has a fully sequential injection system where each injector is squirted individually when the appropriate cylinder is on its' intake stroke.
Later models have coil-per-plug ignition which also requires a knowledge of the engine phase, as does proper knock control.
Very seldom does the V6 cam sensor give trouble, though.
Kevin
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Thanks Kevin
So do you think that there was another problem and because I had it apart to put the sensor on that i put something else right.
I change the crank sensor a couple of weeks ago an that did not fix it.
cbh
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Well, if it fixed the problem then something was wrong. I was just commenting that it was an unusual failure. If all is OK then that's fine. :y
To expand a little, if the ECU doesn't see a valid signal from the cam sensor the engine can be run, because it's not essential, as you say. The drawbacks will be that the knock control system won't work, so the ECU will probably retard the ignition timing to a "safe" value and may impose a rev limit. That's where your drop in power comes from.
It will also be injecting fuel with a "random" timing relative to the cycle of the engine so this can make it run lumpy. Some of the fuel will be "wetting" the walls of the manifold as it's not being injected onto an open intake valve any more. Plenty of non-sequential injection systems did this in the past with no problems but it will put the mixture out slightly and make it a little less efficient.
Kevin
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Hello Kevin
Thank's for the explanation
I always like to know how things work.
Maybe the cam sensor wiring had got old as the car has done 235K and I have no record of it being changed, (I got a lot of paperwork with the car as it was an ex-lease)
cbh
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Cam sensor can throw up weird transmission codes, had this on a 2.2 lately. changed it and all clear!!