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Old 03-17-2019, 12:05 AM
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Shade Tree Welder Shade Tree Welder is offline
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Join Date: Jun 2004
Location: Kankakee County, IL
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Quote:
Originally Posted by Whitetrash View Post
Ron, perhaps a direction to look as you chase this. My thought right away is how does the sense the dist. timing and adjust advance.
The ignition timing on your truck is electronically controlled by the engine controller. Turning the distributor does not change ignition timing, but getting it in the right spot is very important. With the timing controlled by the engine control module, you can't set the timing on these engines with a timing light. It's just all over the place.
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Putting the distributor in the right position on these is called "setting sync". This is best done with a dealer scan tool, but can be done with a voltmeter. You are setting the rotation so the cam sensor (inside the distributor) toggles its signal voltage at the perfect time. It needs to be within 10 degrees of 0 (preferred is 0), if its closer to 20 degrees it will set a code for intermittent loss of cam or crank signal, and if its far enough out it will actually send spark to the wrong pole on the distributor cap, or it will fire to two wires at once. Here is the procedure to set the distributor on your truck without using a dealer scan tool.
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Connect a voltmeter to the distributor sensor connector by removing the end seal and carefully back probing the connector. Connect the positive lead to the sensor output pin (pin 3, either a tan wire with a yellow tracer or a gray wire, depending on vehicle application). Connect the negative lead to battery ground.
Rotate the engine clockwise as viewed from the front, until the number one mark piston Top (TDC) compression on the vibration damper should line up with the zero degree (TDC) mark on the timing chain case cover.
Continue to rotate the engine slowly clockwise until the V6 or V8 mark on the damper(depending on engine type) lines up with the zero degree (TDC) mark on the timing chain case cover. The V8 mark is 17.5┬░after TDC and the V6 mark is 147┬░ after TDC.
NOTE: DO NOT ROTATE THE ENGINE COUNTER CLOCKWISE. IF THE ENGINE IS ROTATED BEYOND THE MARK, RETURN TO STEP 6 AND REPEAT THE PROCEDURE.
With the distributor clamp bolt loose and the ignition switch in the ON position, rotate the distributor slightly in either direction until the voltmeter switches between the sensor transition point of 0 and 5 volts.
Adjust the distributor as close as possible to either side of this transition point and tighten the distributor clamp bolt

Someone else on another site was good enough to post this. The computer handles everything, but you have to set the starting point.
I am going to have to read that a dozen time to understand that...

But thanks.

Here is what the advance was doing.
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