Does the Crank Position Sensor affect Injector Pulse?

[Clinton131]

I have a 02 4.6L Merc with a no start condition that I have linked back to no fuel injector pulse. Does the CKP signal the PCM to pulse the injectors? Or does it only affect spark?

 

[2000StreetRod]

injector pulse timing

I don't know about the 4.6L V8 but I suspect it is like my 4.0L SOHC V6. The camshaft position (CMP) sensor only "tells" the PCM if #1 cylinder is on the compression stroke or the exhaust stroke. All timing (ignition and injector) is referenced by the PCM to the crankshaft position (CKP) sensor. If the PCM loses the CKP signal while the engine is running it attempts to maintain timing based on the last known reading.

 

[waskly]

the theft light goes out with key on engine off?

 

[Clinton131]

I don't know about the 4.6L V8 but I suspect it is like my 4.0L SOHC V6. The camshaft position (CMP) sensor only "tells" the PCM if #1 cylinder is on the compression stroke or the exhaust stroke. All timing (ignition and injector) is referenced by the PCM to the crankshaft position (CKP) sensor. If the PCM loses the CKP signal while the engine is running it attempts to maintain timing based on the last known reading.

Thanks for the reponse. Car did not throw a code for the CKP but I am suspicious of it.

Does anything else come to mind that could prohibit the fuel injectors from pulsing? I was looking for suggestions in another thread:

http://www.explorerforum.com/forums/showthread.php?t=360804

Any suggestions would be great. I am running out of ideas.

 

[Clinton131]

the theft light goes out with key on engine off?

Don't believe that it is a PATS issue if that is where you were going. Already brought it to the dealership in reference to this. They advise it is not a PATS issue. Their diagnosis: All 8 injectors plugged at the same time. They did program a second key. Most expensive key I have ever purchased. See the following thread for more info:

http://www.explorerforum.com/forums/showthread.php?t=360804

 

[thedogzeus]

Crank Position Sensor, does control injector pulse AND ignition spark.

Often these little buggers become intermittant. A little tap with a spanner will usually bring the sensor back online, but suggest to replace it ASAP.

Have seen these causing no start condition on an intermittant basis, without generating a DTC, making them hard to diagnose.

 

[mesqrob]

Crank Position Sensor, does control injector pulse AND ignition spark.

Often these little buggers become intermittant. A little tap with a spanner will usually bring the sensor back online, but suggest to replace it ASAP.

Have seen these causing no start condition on an intermittant basis, without generating a DTC, making them hard to diagnose.

Man, I've got a 97 5.0 with the same issues. I've replaced everything fuel & spark related, & it still acts up. I'm gonna check this Crank position sensor. Thanks for the post