720 Sync

[Mattb]

Im having trouble getting 720 sync. I have had the car running before in 720 sync mode but removed my cam cover and cover position sensor to replace a cam cover gasket. Upon replacement I can't seem to get 720 sync. I have put the cam position sensor back in the same position and I'm I can see from the sync log one cam event every 720 degrees but on cranking the car is showing "360 sync". I can't for the life of me work out what I've done.

Any ideas where to start.

Heres an image of the sync log

IMG_4263 by Barkley Dogue, on Flickr

[stevieturbo]

How does the synclog compare to previous ones where everything was ok ?

You mention one tooth per 720....although it's hard to tell from a poor quality screenshot it looks like you've cam teeth of different size there ?

You're saying the engine runs indefinitely in 360 ?

Synclog shows engine starting, running briefly in 720 then stopping again.

[Mattb]

Hi Steve,
yes its a not a great screen shot. Ive now got the logs from the garage laptop.

From the log there, i didn't actually run the engine, that was purely cranking it. I had previously seen 720 sync when cranking. I think the variance in width of the cam tooth is due to the speed of cranking.

Ive taken the cam sensor out and it has a crack in it, so I'll be replacing that first. Although I'm not sure that will change anything it seems the sensor is incredibly sensitive to proximity to the cam tooth.

[stevieturbo]

What engine etc is this ?

Looks like crank sensor polarity is incorrect ?

And other than some noise....falling edge of cam signal is very inconsistent, although rising edge looks ok. I would definitely not be using the falling edge as the trigger.
No idea if that's a sign of a bad sensor though, or just how your config might behave.

How is it all configured ?

[Mattb]

It's a tvr Tuscan running with crank and cam sensor. It was running perfectly in 720 sync but has been off the road while I did some work. There doesn't seem to be a consistent position for the cam sensor for some reason no matter how much adjustment I do taking it closer to the cam trigger or further away, so have ordered a new one.

[stevieturbo]

It's a tvr Tuscan running with crank and cam sensor. It was running perfectly in 720 sync but has been off the road while I did some work. There doesn't seem to be a consistent position for the cam sensor for some reason no matter how much adjustment I do taking it closer to the cam trigger or further away, so have ordered a new one.

Again, rising edge looks ok. Falling edge looks terrible.

I'm sure some Syvecs team could comment better, but your crank scope trace has wiring reversed over what would be deemed normal and a falling edge triggered signal.

Not sure if your wiring like that, and rising edge are considered the same thing. But again, without knowing how everything is configured, hard to say.

And even with a slightly problematic cam trigger, you could select to ignore cam once in 720sync

But IMO it all needs checked out to see if it is correct.