Cyl 1 no spark / Crank sensor voltage question.

[sgordon1]

91 Explorer XLT
-sigh-
No spark to cylinder 1 (and only cylinder 1, cylinder 5 is just fine).

So far I have replaced: spark wire (swapped with next cyl), new plug, used CKP sensor, used ICM, used PCM, used coilpack (resistance checks out) with items from local pick and pull. I suppose I could be VERY unlucky and have grabbed something with the identical problem but...

At the crank position sensor, BOTH wires going to it read 1.5V when ign is on and sensor is unplugged. My Haynes guide is a bit vague, but I was expecting only one of the wires to read 1.5V and the other 0V or indeterminate. Could this be my issue? I unplugged the ICM and checked for a short across the two wires, there is none.

How the heck can cylinder 5 fire perfectly and yet not cylinder 1??? Don't they both spark at the same time??? They use the same coil. Surely I would at least see spark at #1 when #5 fires.

Note, I have used a tach with rpm sensor on the wire.

The number#1 plug is a bit dirty along the threads - I've tried to clean it a few times but surely this couldn't be the cause.

Any help appreciated. I'm ready to cry. Not pretty. Off to get an OBD code reader (not that I think that is going to help).

 

[sgordon1]

update - still could use some suggestions

So for fun I switched the wires for cyl 1 and 5 with eachother.
Cyl 1, firing from coil location 5 fires just fine at twice rpm.
Cyl 5, now trying to fire from coil location 1 intermittently fires below 1000rpm.

Above 1000 rpm I get no signal whatsoever on the pickup on the timing gun I am using.

So in effect, the vehicle is running slightly better.
I'm going to try another coilpack from the scrapyard.
I can't comprehend how it can be anything other than the coilpack at this stage but I'm hoping someone else on the forum has come across this before and can advise...

Much appreciated.

 

[Alan_V]

So for fun I switched the wires for cyl 1 and 5 with eachother.
Cyl 1, firing from coil location 5 fires just fine at twice rpm.
Cyl 5, now trying to fire from coil location 1 intermittently fires below 1000rpm.

Above 1000 rpm I get no signal whatsoever on the pickup on the timing gun I am using.

So in effect, the vehicle is running slightly better.
I'm going to try another coilpack from the scrapyard.
I can't comprehend how it can be anything other than the coilpack at this stage but I'm hoping someone else on the forum has come across this before and can advise...

Much appreciated.

Can you clarify what you mean by "Cyl 1, firing from coil location 5 fires just fine at twice rpm??" Also, what are your voltages for other coils?