I have a 525 merc engine that has starting missing at 4800 to 500 rpm the scan tool shows a code for ( vr sensor std) any ideas ??? I have'nt seen this before

Crank or cam sensor?

The crank sensor is the only thing that came up when we googled it we tried 2 different ones and still the same and the crank trigger wheel is not rusted it runs ok till the temp goes up ,the water temp is a little hi 180 thanks for the response

On our Formula 353 with 525s we had an issue at higher rpms there was a random "ping" sound , like tapping a hammer on hollow metal very lightly, starboard engine. Replaced the cam sensor assembly and fixed it. And yes it was $800 for the part.

I can get that external cam sensor for less than half of that. We have seen quite a few of them go bad and they usually cause a 4000 rpm rev limiter.
Eddie

These them Eddie ?
ACDelco 213-350 GM Original Equipment Engine Oil Pump Driveshaft with Camshaft Position Sensor
https://amzn.com/B000EQPA00

Now you tell me!