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Old June 9th, 2003, 08:15
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satan satan is offline
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Join Date: Apr 2003
Location: Lakewood, CO USA
Posts: 327
I see that no one has offered-up the Distributor's sync sensor as a place to look -- I'll detail a few tips below -- The Sync sensor is used in combination with the CPS to determine just which piston is at TDC (the CPS can only show crank position and #1 and #6 are at TDC at the same time, one on compression and the other at exhaust)... If the data from the DistSync is ambigous or missing, the ECU will try to fire the #1 cylinder, every other time the TDC mark flys past the CPS - if the engine doesn't start, then it'll skip one of the TDC instances and try to fire #1 180* off from where it started before... This could be part of why you're getting good starts & bad starts.

The Dist Sync signal does have a tendancy to drop it's ground reference and become unpredictable -- Leme type some thoughts:

So the sync connector out of the dist is a round 3-position connector --

Pin A = Black - Ground - (chassis gound, both in the dist and for the harness - you can unplug the connector to check both grounds seperately - it's OK to add a chassis ground to this line)

Pin B = Blue - Output - (to pin C16 of the ECU - should show about 5 volts static between Pin-B and Pin-C - connected to harness, key on, engine off)

Pin C = Gray - Supply (should be about 7VDC from pin C5 of the ECU)

While you're looking at the static voltage between Pin-B and Pin-C, if you crank the engine, you should be able to see the voltage fluctuate as the sensor rotates (qty=1 wiggle per rev, so it's not that impressive)

[edit] I seem to remember the gray wire on Pin-C having a stripe as well... -- was just looking at a dist yesterday, but can't remember much more [/edit]
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