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Number eight spark plug not firing

Tiny
GLIDERBOY19
  • MEMBER
  • 1988 CHEVROLET 1500
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 625,340 MILES
I changed the distributor, wires and plugs after having an intermittent skip in the engine. The old distributor was in bad shape. After completing the install I cranked the engine and the skip was still there all the time. I checked the compression on #8 and found it good. Tested with a separate plug and plug wire and found no spark at #8. Suspect the ESC or ECM. What might be the problem?
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Monday, July 22nd, 2019 AT 11:55 AM

10 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon,

What was the compression?

If you installed a new distributor and have no spark to 1 cylinder, then something is wrong with the distributor. What kind and where did you buy it?

The ECM has no involvement in spark to number 8.

Roy
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Monday, July 22nd, 2019 AT 12:32 PM
Tiny
GLIDERBOY19
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  • 6 POSTS
Bought the new distributor at O'Rielly auto. The old one did the same thing.
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Monday, July 22nd, 2019 AT 1:01 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Did you set the plug on the manifold to be sure there is no spark?

It does not make sense for not having spark on 1 cylinder with all the resr firing.

Is the wire grounding anywhere?

Roy
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Monday, July 22nd, 2019 AT 1:05 PM
Tiny
GLIDERBOY19
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  • 6 POSTS
Compression on #8 was 150lbs. This engine has 92,000 miles on it. The problem began as intermittent.
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Monday, July 22nd, 2019 AT 1:05 PM
Tiny
GLIDERBOY19
  • MEMBER
  • 6 POSTS
Tied the test plug to a good ground. Got the same response.
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Monday, July 22nd, 2019 AT 1:07 PM
Tiny
ASEMASTER6371
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Did you change the cap and rotor?

Roy
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Monday, July 22nd, 2019 AT 1:11 PM
Tiny
GLIDERBOY19
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Yes. Changed the rotor and cap. Also new distributor module.
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Monday, July 22nd, 2019 AT 1:21 PM
Tiny
ASEMASTER6371
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A new module should have come with the distributor.

None of this makes any sense. You have changed all the components with no result in spark for 1 cylinder.

Does the shaft in the distributor have any lateral play?

Roy
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Monday, July 22nd, 2019 AT 1:24 PM
Tiny
GLIDERBOY19
  • MEMBER
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No.
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Monday, July 22nd, 2019 AT 1:30 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Okay, something was missed somewhere.

Start over and recheck everything. Check the wire with an ohmmeter and tell me the resistance.

Roy
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Monday, July 22nd, 2019 AT 1:34 PM

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