YB Cosworth phase sensor gap

**OZMK1** · 29-03-2021, 08:47

My tuner checks it with the scope then a power run on the dyno before it leaves the workshop. Let's face it the phase sensor, for whatever reason is a problem (I'm not the only person who's experienced this) and have no doubt the digital hall effect upgrade will be worthwhile. Happy to report back on it Steve.

**stevieturbo** · 29-03-2021, 17:29

Yes it is a problem, if the OEM phase sensor in good order, does work, can work, so should not be a problem is what I'm getting at.

But absolutely, moving to a new and more modern hall setup, there are no downsides. I'd still do the 12-1 crank even with the new hall phase.

**OZMK1** · 30-03-2021, 11:00

Something I've been thinking about the past few days- After getting the car back from tuner in good working order, the clutch had to be replaced so I did that and also water pump, TIMING BELT, and tensioner. Yeah, it's safe to say the 5yo belt had some stretch in it and that's what the home sensor was set with. I reckon the new belt would have shifted the sync % The problem didn't occur until after 700km. Will a digital hall effect suffer the same problems due to belt stretch?

**Graham** · 30-03-2021, 11:09

bearing in mind its a very short belt length from the aux pully to the crank pulley i cannot see belt stretch being the issue. most cam/phase senors are up at the top of the engine, if a tiny bit of belt stretch would cause issues then 90% of cars on the road would have cam/crank correlation issues

**stevieturbo** · 30-03-2021, 16:54

I would say the belt is in no way an issue

**OZMK1** · 05-04-2021, 10:52

I would like to wrap this topic up and extend my thanks for all the help from fellow members.
I discovered yesterday the gap was not the problem, it was the rotation of the sensor. I was able to get the car running great from rotating the distributor which indicated the timing was shifting somehow. I put the timing light on and noticed it jumping between 10deg and 12deg before TDC. A quick google suggested the problem could be a sheared roll pin in the dizzy gear. And this is what was found