Should the engine run WITH both cam sensors UNPLUGGED?

777funk · Post by **777funk** » 29 Jan 2025, 03:22

My son bought a XC-70 as his first car with a blown head gasket. He was able to repair the car. No more breached head but has been getting timing codes. No idea if they were there before since it had unknown issues. We retimed it so that with the crank on the mark, both cam slots (rear of engine... i.e. drivers side in US) are parallel to the seam of the cam cover/head after several engine rotations. So we're pretty sure it is perfectly in time. But we're still getting cams over advanced codes. This led me to next question if maybe there is an electronics issue.

I unplugged both cam sensors and there was no change in sound and the engine kept running. Is this normal?

dikidera · Post by **dikidera** » 29 Jan 2025, 05:31

Yes it is normal. But if you are getting codes, I don't believe you have timed it right. You also didn't say if you correctly timed the VVT hub(or hubs).

777funk · Post by **777funk** » 29 Jan 2025, 06:13

dikidera wrote: ↑29 Jan 2025, 05:31 Yes it is normal. But if you are getting codes, I don't believe you have timed it right. You also didn't say if you correctly timed the VVT hub(or hubs).

I think it is timed correctly. The crank is on its mark and both cams were clocked full CW (top of gear turned right) when facing the belt. At the rear of the engine (opposite the belts), the cam slots are perfectly parallel to the seam of the head/cam cover. Several revolutions of the engines were spun to double check that this timing repeats and it does.

dikidera · Post by **dikidera** » 29 Jan 2025, 06:17

It has been a while since I last timed my engine, but I did use a tool for that. I can't remember if the cams were supposed to be parallel to the seams, or to each other for that matter.

Post by **jonesg** » 29 Jan 2025, 08:17

if the cam tool was used to remove th hubs and it was in time before the job they should still be good,
slots should be in line, intake up, exh down.

I think the problem is the cam sensors , I'm not saying they're bad, vida would show where the problem is.
It can be a lack of oil pressure to the vvt solenoid resulting in slow reaction, that causes the cam sensors to register mis-timing.
If you don't have vida...get it.
In the meantime ensure you have 5v reference voltage at the cam sensor plugs.
The wrong oil can cause this problem, as can swollen O rings in the opil pan feed tube for the vvt solenoids.
The wrong oil at this time of yr can be like treacle, I know I fixed mine with just an oil/filter change.
All of the above is from vida, its not my opinion.

dikidera · Post by **dikidera** » 29 Jan 2025, 08:36

Btw, the reluctor wheel breaking is a common issue, so that should be checked as well

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