What EXACTLY does the crank sensor do?

[streetknight]

Does it control fueling thru the injectors or is that the cam sensor? My car is cranking just fine when it's cold, BUT after you drive it for a while and get it hot and try to crank it back it's like the timing is way high.

and every now and again when it does crank it rolls a little black smoke.

I just built the engine and heard a little clicking sound which I thought I had narrowed to the crank sensor scraping on the balancer. I took it loose to adjust and my crank sensor was in 3 pieces. The little tabs that hold it in the bracket on one side were gone. Could this be causing my problems?

Also, I know I have to have a new one. Are they dealer only, discontinued, parts store or what?

Thanks

 

[bruce]

Does it control fueling thru the injectors or is that the cam sensor? My car is cranking just fine when it's cold, BUT after you drive it for a while and get it hot and try to crank it back it's like the timing is way high.

and every now and again when it does crank it rolls a little black smoke.

I just built the engine and heard a little clicking sound which I thought I had narrowed to the crank sensor scraping on the balancer. I took it loose to adjust and my crank sensor was in 3 pieces. The little tabs that hold it in the bracket on one side were gone. Could this be causing my problems?

Also, I know I have to have a new one. Are they dealer only, discontinued, parts store or what?

The crank sensor generates what's called the *Distributor Reference Pulses*. They are set to occure at 10d BTC. When cranking, and at less then 400 RPM the ecm, is in batch fire mode. Once the RPM goes over 400 RPM, the ecm switchs the EST to active, and then the ecm takes control of the timing. About the same time, the ecm will see a cam reference signal, and go to batch fire mode. Mind you, this is all happening with in a few msec., of the engine starting.

A loose or broken crank sensor can play havic on when the ecm *sees* the reference pulse, ie it has no idea of when 10d BTDC happened.

Some liberties were taken in the exactness, just to make it an easy read.

GM, AC/Delco, is the place for ignition stuff, IMO.

 

[getchasum]

What do you think broke the bracket? You may want to check the balancer and crankshaft end play before installing a new one.

 

[chrisgarrett]

Make sure your balancer is torqued correctly. It may be wobbling. Or the fins on the back of the balancer may be out of alignment.

 

[streetknight]

The bracket isn't broken. Just the sensor itself. You know the little tabs on top and bottom of the sensor that hold it in the pinch bracket? Both of those are broken off the back side where it wobbles in the bracket.

 

[bruce]

The relustor/ vanes are out in the open, a piece of gravel could go thru there, and wreck the sensor, and you'd not know it, until the pieces fell out.