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View Full Version : LBZ cam/crank waveform


schwoch1
November 17th, 2014, 05:36 PM
Sooooo.... does anyone out there happen to have a good waveform of the cam/crank relationship on a LBZ Duramax??? Just into the beginning stages of a custom project using the LBZ controller and I need to know what the relationship of the cam and crank is so I can get the trigger wheels mounted correctly to my engine!

THanks in advance
Mike
asmithIII
November 30th, 2014, 09:38 PM
Seems that two sensors are used to determine position. The combination of sensors varies depending on if the engine is at idle or not at idle. Thinking that both crank and cam position sensors are used. If you think that the LMM engine waveform is helpful, then we'll work together on your question. We need to see if EFI Live can scan and record those two sensor outputs as just external analog voltage inputs into the FashScan.
DURAtotheMAX
December 1st, 2014, 03:24 AM
The sensors are hall-effect sensors.

The ECM requires both to run. With either the cam or crank sensor disconnected, the engine will not start. The ECM uses the CMP sensor for #1 cylinder TDC reference, and the CKP sensor for RPM.
schwoch1
December 3rd, 2014, 03:18 PM
The sensors are hall-effect sensors.

The ECM requires both to run. With either the cam or crank sensor disconnected, the engine will not start. The ECM uses the CMP sensor for #1 cylinder TDC reference, and the CKP sensor for RPM.

Thanks for that info! I was kinda wondering if they ran when/if it drops the cam sensor. I know most GM systems will run without a cam reference, but beings GM did not design this system, I was kinda curious!

Mike
DURAtotheMAX
December 4th, 2014, 08:36 AM
I know most GM systems will run without a cam reference, but beings GM did not design this system, I was kinda curious!

Its not because GM didnt design the system..........its because its a common rail diesel.........

The ECM absolutely HAS to know when cylinder #1 as at TDC compression stroke.

Yeah, with a gas engine, the ECM can transition to backup tables/waste-spark/batch-fire when it loses cam position signal, and it will run with no cam signal. But this isnt a gas engine. You cant just fire each injector once per crankshaft revolution on a diesel engine and expect it to work.

Ben