S-10 no spark bad compression

Tiny
BERGUM
  • MEMBER
  • 2010 CHEVROLET S-10
I have a 93 s-10 4x4 (143,000mi) with a 4.3 (z VIN)with an automatic tranny. It has a slight knock during acceleration and feels like it's missing. If I keep it in park and keep the RPM's up there is no noise only in forward gears.I found a plug that had broke and replaced it but no fix, since then I changed the 02 sensor, knock sensor and fuel filter.I had a guy check for spark at the distributor cap and I think it was #3 & 5 did not have spark at the cap. He then did a compression check on the number 3 cylinder and said it was only at 50 pounds. Will no spark affect the compression of a cylinder since the coil is unhooked for a compresion test. At my whitts end trying to figure out why my truck isnt running right. Any help would be greatfull.
Friday, May 18th, 2007 AT 7:43 PM

5 Replies

Tiny
SERVICE WRITER
  • MECHANIC
  • 9,123 POSTS
Since the gauge is where the plug would go, the cylinder wouldn't have spark anyways. You obviously need to resolve the spark issue if you havn't already. I would try cleaning the intake valves to see if that helps the compression. There may be a carbon build up, preventing the seal.
One product I like is seafoam, although GM top engine cleaner is also good as is castle products.
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Friday, May 18th, 2007 AT 8:30 PM
Tiny
MATTHEW999
  • MEMBER
  • 2 POSTS
  • 2000 CHEVROLET S-10
  • 200,000 MILES
4.3l fuel pressure. 60psi good spark at end of coil wire but no fire at plugs, installed new dist. Cap and rotor button
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Monday, July 13th, 2020 AT 1:14 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
What about the coil wire to the distributor?
Roy
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Monday, July 13th, 2020 AT 1:14 PM (Merged)
Tiny
MATTHEW999
  • MEMBER
  • 2 POSTS
Strong fire at end of coil wire, none at end of plug wires
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Monday, July 13th, 2020 AT 1:14 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Re check your cap and rotor. Something wrong in there

Roy
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Monday, July 13th, 2020 AT 1:14 PM (Merged)

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