1993 5.7 one cylinder no spark

[Jmcm]

Good evening, chasing a gremlin that I can’t figure out. Felt a miss today and narrowed down to #2 is not getting spark from the distributor cap on the #2 wire. I swapped two wires from each other, changed the cap rotor and coil and still no luck on that #2 post. Any thoughts?

 

[SUBURBAN5]

Oem parts?

 

[Jmcm]

thanks for the reply, no not oem but I’m confused why faulting on only one cylinder all of a sudden

 

[SUBURBAN5]

That's a new one for me. I would test the parts. If there good quality name brands that's one thing. But if there some knock off Chinese that's another. I'm use to the vortec caps . I know the tbi is a different set up. Having spark on 7 cylinders makes me suspect something is crossing over or at that position something is blocking spark. Vortec caps are known for this but ours are sideways set up as to your top fed setup.

 

[Schurkey]

HOW are you testing to find no spark on one cylinder?

Depending on your test method, a fouled plug is likely. (Has spark, but the voltage bleeds-off before it builds high enough to jump the plug gap.)

 

[Jmcm]

I used my timing gun and put it on the #2 plug wire ( one not firing)to test for spark . I also swapped the plug wire with another cylinder and still had the same problem on the #2 cylinder

 

[Jmcm]

Problem solved, bad pick up coil

 

[Schurkey]

An inductive pickup functions on voltage build-up. A fouled plug doesn't allow voltage build-up, so the inductive pickup has nothing to trigger it.

I have no idea how a GM HEI pickup coil can cause no-spark to one cylinder. Ford or Chrysler...maybe. It would be extremely unlikely, but possible. GM? No.

 

[Jmcm]

Well back to the drawing board, was running as smooth as can be ran if around town for 30 minutes. Parked it for two hours went back out and now no spark at the same cylinder. I do know this cylinder has a bad oil ring ( plug was gummed up) refreshed with a new plug and still no spark. I’m clueless. Have been using my timing gun to verify spark. Even swapped the wire with a known good one just to verify

 

[Jmcm]

Well back to the drawing board, was running as smooth as can be ran if around town for 30 minutes. Parked it for two hours went back out and now no spark at the same cylinder. I do know this cylinder has a bad oil ring ( plug was gummed up) refreshed with a new plug and still no spark. I’m clueless. Have been using my timing gun to verify spark. Even swapped the wire with a known good one just to verify

This motor is tbi, does not have a hei distributor