Running rough and smells like gas/rotten eggs

1996 CHEVROLET S-10
163,000 MILES • 2.2L • 4 CYL • 2WD • MANUAL
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MIDORI95
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Background: Truck was having a cylinder 3 misfire. Replaced spark plugs, works great after. Leave truck parked for a week without running, cylinder 3 misfire pops up again. Replaced spark plug wires and fuel filter. Cylinder 3 misfire, rough idle, going into third is too much and smells like gas/rotten eggs. Lots of shaking when turning air on. Anything else to look at?
Jan 9, 2021 at 12:29 PM
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ASEMASTER6371
  • ✓Experienced Mechanic
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Good morning,

I would start by checking the compression to be sure there is no internal issue.

https://www.2carpros.com/articles/how-to-test-engine-compression

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Can you give me the code numbers that were set?

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Roy
Jan 10, 2021 at 12:05 AM
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MIDORI95
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Thanks for the response Roy! I will look into getting the compression test. As for the code it is P0303.
Jan 11, 2021 at 9:36 AM
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ASEMASTER6371
  • ✓Experienced Mechanic
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Thank you. The 303 indicates number 3 cylinder misfire.

Let us know the results of the compression test.

Roy
Jan 11, 2021 at 11:17 AM
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MIDORI95
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Here are the results from the compression test:
Cylinder-PSI
1-137
2-135
3-110
4-93
Jan 16, 2021 at 11:56 AM
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ASEMASTER6371
  • ✓Experienced Mechanic
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Thank you.

Number 4 cylinder is the issue. Number 3 is close behind.

https://www.2carpros.com/articles/symptoms-of-low-compression

https://www.2carpros.com/articles/the-reasons-for-low-compression

You may have either bad valves or piston rings.It would be better to consider replacing the engine with a good used motor than repairing this engine.



Roy
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Jan 16, 2021 at 12:17 PM
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MIDORI95
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Thank you, I appreciate the guidance!
Jan 16, 2021 at 12:25 PM
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ASEMASTER6371
  • ✓Experienced Mechanic
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You are welcome.

Always glad to help.

Roy
Jan 16, 2021 at 12:27 PM
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