Crankshaft sensor

[CTE]

My car will not start!....having checked several things it appears there no feed to the coil pack, and whence no spark. The engine is a BOA V6 running an Emerald ECU. The ECU has been checked out at Emeralds and is fine. Dave Walker says its most likely to be something to do with the crank shaft sensor. I have checked the wiring as best I can with limited equipment, and it all looks ok, and have subsequently removed the sensor. The question is...how do I check the sensor operation? I have put my continuity meter accross the terminals and then moved the sensor accross a bolt head. The sensor is currently open circuit and there appears to be no change in this condition when moved accross the bolt head. Am I doing the right thing, or am I wasting my time??

Thanks

[stevieturbo]

CTE said:

My car will not start!....having checked several things it appears there no feed to the coil pack, and whence no spark. The engine is a BOA V6 running an Emerald ECU. The ECU has been checked out at Emeralds and is fine. Dave Walker says its most likely to be something to do with the crank shaft sensor. I have checked the wiring as best I can with limited equipment, and it all looks ok, and have subsequently removed the sensor. The question is...how do I check the sensor operation? I have put my continuity meter accross the terminals and then moved the sensor accross a bolt head. The sensor is currently open circuit and there appears to be no change in this condition when moved accross the bolt head. Am I doing the right thing, or am I wasting my time??

Thanks

You say you have no feed to the coils. No power feed to the coils has nothing to do with the crank sensor.

So do you have 12v to the coils or not ?

[Graham]

The emerald ecu has an indicator LED on it that flashes each time it picks up the crank sensor, whats yours doing when you turn the engine over..

[CTE]

Thanks for your thoughts..the ECU light is on red, but is not flashing. I pulled the 4 pin connector off the coil pack and with the negative probe of the volt meter onto the engine block, I did not get any readings from any of the four pins. The iginition was on, but it was not practical to turn the engine over when doing this.

[stevieturbo]

CTE said:

Thanks for your thoughts..the ECU light is on red, but is not flashing. I pulled the 4 pin connector off the coil pack and with the negative probe of the volt meter onto the engine block, I did not get any readings from any of the four pins. The iginition was on, but it was not practical to turn the engine over when doing this.

So once again, the problem is you are lacking 12v power to certain devices.

That has nothing to do with the crank sensor.

[CTE]

Stevie, i`ll give you a bit more of the picture...

The car has sat outside over the winter months under a car cover, and the few occasions I ran it up during the worst of the cold weather, it started fine. I decided to fit the cover a little looser early Feb (to allow it to breath and stop condensation), and then we had some strong wind and rain (doh!), the result of which was the inner sill bacame flooded, and the fuse board with some relays sits in this sill. The ECU sits above on a bracket fortunately. When I came to start the car a couple of weeks ago, it was all dead, and when I connected another battery the fuel pump fired up as did the electric fan, which turned out to be short circuited relays and a wet fuse board. I have fitted new relays and dried and checked all the fuses, which were all fine. At some point when it all got wet the fuel pump and fan must have started up and run until they flattened the battery. The iginition would have been off during this time. I have checked all the wiring and components in this area and all seem fine, and as we know it turns over with fuel getting to the cylinders fine, there`s just no spark.
It`s about 5 years since I wired this up from one of Emeralds schematics, and it was all fairly straight forward, but all my notes are buried under tons of garage stuff in our back garden because we are having an extension built with an all important decent garage...whence why the car is in a fieled under a cover. If its not the crank sensor, then it must be soemthing to do with the feed to the coil pack...could you remind me where this comes from? I guess the firing signals come direct from the ECU, but is there a seperate +/- voltage supply to the coil pack?
I agree there is no reason for the problem to be the crank case sensor, nothing has changed down there and it was all covered in a film of oil, so there would be no short circuits etc. The sensor itself should be a pretty reliable device?

[Mr2Mike]

The crank sensor should not be open circuit if it's a variable reluctance sensor (the vast majority are). These sensors are effectively a coil of fine wire, with a typical resistance of 300 ohms up to maybe 1200 ohms depending on make and model.

[CTE]

This one has a black plastic case with an approximate 2mm dia metal pin flush at the crankshaft end of the sensor body, and its magnetic?

[stevieturbo]

CTE said:

Stevie, i`ll give you a bit more of the picture...

The car has sat outside over the winter months under a car cover, and the few occasions I ran it up during the worst of the cold weather, it started fine. I decided to fit the cover a little looser early Feb (to allow it to breath and stop condensation), and then we had some strong wind and rain (doh!), the result of which was the inner sill bacame flooded, and the fuse board with some relays sits in this sill. The ECU sits above on a bracket fortunately. When I came to start the car a couple of weeks ago, it was all dead, and when I connected another battery the fuel pump fired up as did the electric fan, which turned out to be short circuited relays and a wet fuse board. I have fitted new relays and dried and checked all the fuses, which were all fine. At some point when it all got wet the fuel pump and fan must have started up and run until they flattened the battery. The iginition would have been off during this time. I have checked all the wiring and components in this area and all seem fine, and as we know it turns over with fuel getting to the cylinders fine, there`s just no spark.
It`s about 5 years since I wired this up from one of Emeralds schematics, and it was all fairly straight forward, but all my notes are buried under tons of garage stuff in our back garden because we are having an extension built with an all important decent garage...whence why the car is in a fieled under a cover. If its not the crank sensor, then it must be soemthing to do with the feed to the coil pack...could you remind me where this comes from? I guess the firing signals come direct from the ECU, but is there a seperate +/- voltage supply to the coil pack?
I agree there is no reason for the problem to be the crank case sensor, nothing has changed down there and it was all covered in a film of oil, so there would be no short circuits etc. The sensor itself should be a pretty reliable device?

AArrgghhhhhh

You say you have NO 12v to the coil. FIX THAT.

It has nothing whatsoever to do with the crank sensor. FACT.

I have absolutely no idea how your car is wired to even suggest where the coil is fed from. An obvious step would be to trace the wiring !

[maniac0796]

Most crank sensor's are self inductive, so set your multimeter to AC volts, and see what you get then. I would imagine at idle around 1 to 2 volts

[fatjon]

"The sensor is currently open circuit and there appears to be no change in this condition when moved accross the bolt head. Am I doing the right thing, or am I wasting my time??"

If you are checking it correctly with a known good multi meter then it IS faulty. It should not be open circuit! I have fitted several emeralds and many many other engine management systems using VR sensors for the crank position. Take my word for it, if it is open circuit it is screwed.

What you should see is a resistance of between 300 and 1500 ohms and it should generate a small voltage spike as you move a steel bolt head quickly towards it or away from it. The spike will be no more than a fraction of a volt and most digital meters will not see it very clearly. An older anolog meter is better or an oscilloscope. Most of the sensors are less than £30 so if you are SURE it's open circuit just buy a new one.

[fatjon]

BUT

I agree that zero volts on any of the coil pack connectors is also a fault which will also need sorting if it is to run.

[tinker-27]

The emerald should have two 12v feeds to it check them , check the earth to the ecu , CHECK the 12v to the coils , even if you disconnect the coils the led on the ecu should go green on cranking . If the crank wheel is external it might have gone rusty which causes problems, it could be inductive or digital sensor , I've had a few cars and bikes in after winters that have had wires chewed by mice !!! It's very common . Does the fuel pump prime for a second of so when you put the ignition on ? . One last thing what's the battery voltage needs to be 11+ (12 +really) ,