Kv average per cylinder

[roadrunner_70]

Have a question for some master techs out there. The average Kv for each cylinder is between 10Kv and 12Kv, except for one cylinder, which is around 6-8Kv. The coil wire is showing about 15-17Kv. Could this mean that there is low voltage going to one cylinder due to distributor? Rotor? Module? Coil?, or a bad wire/plug? Wires and plugs are near new.

[AKWE-gt]

Originally Posted by roadrunner_70

Have a question for some master techs out there. The average Kv for each cylinder is between 10Kv and 12Kv, except for one cylinder, which is around 6-8Kv. The coil wire is showing about 15-17Kv. Could this mean that there is low voltage going to one cylinder due to distributor? Rotor? Module? Coil?, or a bad wire/plug? Wires and plugs are near new.

i think the meter is reading ohms not volts if your reading the resistance of the wires. the 6-8kohm wire is probably the shorter wire and the 15-17kohm wire is probably the longer wire, this seems pretty normal.
is it missing or something?

[J-Ri]

You can measure voltage with an inductive pickup. If one cylinder is not getting enough voltage, it could be one of four reasons. As you said, it could be a problem with the distributor. The conductor in the wire could be cracked, which creates a voltage drop. The third reason would be that cylinder is running lean. The fourth reason is low compression. I hope it's not that. Low compression on just one cylinder usually means cracked rings, worn cam, bent lifter, burnt valve, etc. Swap the wire on the lower kV cylinder with another (swap on distributor too). If the low reading follows the wire, replace it. Otherwise it's probably either lean or low compression.

[roadrunner_70]

It's the #5 cylinder on a 4.3L, so it could be running lean. I tend to lean toward the wire having a poor connection. Thanks, I'll try the wire swap when the engine's cool.

[skipr]

What are using to test KV? You have an old school Sun scope, or a fluke ociliscope? If you suspect low commpression do a leakdown test. It narrow's down the cause, it's the opposite of compression test.

[AKWE-gt]

Originally Posted by J-Ri

You can measure voltage with an inductive pickup. If one cylinder is not getting enough voltage, it could be one of four reasons. As you said, it could be a problem with the distributor. The conductor in the wire could be cracked, which creates a voltage drop. The third reason would be that cylinder is running lean. The fourth reason is low compression. I hope it's not that. Low compression on just one cylinder usually means cracked rings, worn cam, bent lifter, burnt valve, etc. Swap the wire on the lower kV cylinder with another (swap on distributor too). If the low reading follows the wire, replace it. Otherwise it's probably either lean or low compression.

how can a lean condition and low compression cause the distribitor to deliver a lower voltage to a cylinder?

[J-Ri]

I takes more voltage to arc in compressed air, because the molecules are packed togeter, increasing the resistance. I'm sorry, I got the rich/lean mixed up. Running rich takes less kV to jump the gap.

[roadrunner_70]

I'm using an "Alltest 5400" tester with inductive pick-up. It gives a readout of average Kv on a digital display.