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Bad Crank Position Sensor?


LeftHander

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I've got a 2000 short cab/short bed 3.0L 4x4 auto that won't quite start. Been sitting with a bad trans, but ran nice.

Made the mistake of taking off the coil to swap onto my '96 to diagnose a rough engine. The 2000 coil was mounted backwards, so when I put it back I rotated it to the correct position, and it wouldn't start. Plug wires were now wrong. Re-did the plug wires by copying the '96 3.0L.
No start. Checked the book for wires, and it agreed with the other engine.

P.O. had the heads replaced, H2o pump, and other stuff. I wondered if they might have installed the CPS out of phase to match the coil (or vice versa), so I swapped that 180*, and no change. Played with that for a while, and am no longer sure what it was originally set at. Now have it where it belongs, according to the book.
Discovered that it has no connection to the ignition system. Computer and crank sensor is all they use.
So, swapped in my old '96 computer, and get the same result. Sounds the same, coughs and bangs a bit, like it wants to start, but sounds like it is too far advanced.

So, any suggestions? The only thing I haven't tried yet is a new crank trigger sensor. NOT taking that off the '96!
Judging by the '96 computer (which came off a running engine), that is not the problem, but I fail to see how the trigger could be bad. If it wasn't working, would the ignition even fire?
 


RonD

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Crank sensor is working if it "pops" at all

Good picture here of the Coil pack, its the same for 3.0l and 4.0l: https://www.taurusclub.com/forum/attachments/maintenance-repair/66821d1371256829-ford-taurus-mercury-sable-coil-firing-order-reference-taurus-sable-coil-firing-order.jpg

You see where the 4 wire plug in is, it is usually located between 3 and 2 spark plug wires.
Doesn't matter what direction the coil is mounted, can be upside down it you want
Just look at where the 4 wire connector is and that tells you where 3 and 2 and then 1 go

Once you have 1, 2 and 3 cylinders/wires connected then you just need to PAIR THEM
across from 3 will be 4
2 is paired with 6
1 is paired with 5

So you will have
3 4
2 6
1 5
front

or
1 5
2 6
3 4
front

or

1 2 3
5 6 4
front

There are only 3 coils in this coil pack
So 2 spark plugs must fire at the same time, those are the PAIRS
 

LeftHander

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I'm fairly sure the plug wires are correctly positioned in the coil pack. I'll take a flashlight out and take another look to verify I haven't gotten confused.

Forgot to mention that in the middle of all this I replaced the coil with a new one. The result was dramatic, but I don't know why. It went from firing so far in advance that it would nearly stop rotating (big thumps), to a more sedate cough like it is just a bit too far advanced, and almost starts. All wiring was exchanged from coil to coil one at a time to avoid mistakes.

The apparent change in timing when the coil was swapped makes no sense.

Confirmed correct plug wire routing:
3-4
2-6
1-5
front

Might do new plug wires tomorrow. No idea how old they are. Maybe they're cross-leaking arc.
 
Last edited:

RonD

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Unless the coil pack is labelled with correct order, Reverse the order and see what happens
1 5
2 6
3 4
front
 

alwaysFlOoReD

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Quadruple check the 465 order. I goofed even after checking twice.
 

LeftHander

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2WD
YES!
Reversed the end wires, and it runs.

Thank you, Ron.

I'm guessing the wiring harness on the truck side is wrong, and not the coil, since more than one coil pack exhibits the reverse effect. Explains why they mounted the coil backwards, to keep the plug wires in the normal location.

Truck has had prior work done, so I'm guessing somewhere along the line, a plug or pins got swapped.

Next project: fix the trans...
 

RonD

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Good work :icon_thumby:

Thanks for posting the fix
 

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