Help? Cranks but no start

71boss351

Member
Took the car out yesterday. Ran fine but i noticed the Tach was jumping around. Shut the car off went to work came out and the car cranked over but wouldn't fire? FAST XFI and TR 6 ignition. Wild guess is the crank sensor?
 

turbo nasty

Turbo Dojo / MNTR
Took the car out yesterday. Ran fine but i noticed the Tach was jumping around. Shut the car off went to work came out and the car cranked over but wouldn't fire? FAST XFI and TR 6 ignition. Wild guess is the crank sensor?
Tach jumping was the TR6 kicking out a code. Crank sensor is spark and cam sensor is fuel. Look at your leds on your XFI box during cranking you should see Crank, Cam and the Injectors lights. And go from there
 

TurboBob

Resident mad scientist
Staff member
The relationship of cam and crank sensors is a little more involved. The crank sensor is the trigger for both Spark and Fuel, but until the ignition module (TR6 in this case) detects a cam sensor, no crank sensor signals are allowed to pass thru to the ECM (XFI in this case)

Look inside the TR6 unit at the LEDs, my guess is that the CAM led does not change state when cranking. Could be the cam sensor itself, or electrical connections at the TR6 or cam sensor.

Bob
 

turbo nasty

Turbo Dojo / MNTR
The relationship of cam and crank sensors is a little more involved. The crank sensor is the trigger for both Spark and Fuel, but until the ignition module (TR6 in this case) detects a cam sensor, no crank sensor signals are allowed to pass thru to the ECM (XFI in this case)

Look inside the TR6 unit at the LEDs, my guess is that the CAM led does not change state when cranking. Could be the cam sensor itself, or electrical connections at the TR6 or cam sensor.

Bob
Good info as well...My mind was check at XFI first and thats the furthest point in the circuit. Good luck 71 Boss
 
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