COULD A FAULTY MAP SENSOR CAUSE AN ENGINE TO BLOW SMOKE?

  • Tiny
  • wmika@frontiernet.net
  • 1987 Chevrolet S-10
  • 69,000 miles

Replaced head, push rods, and water pump
Running good for 2 weeks, still a little rough at cold starts.
Just started to blow smoke at idle after running at highway speed. Clears up after back up to speed. Oil is clean, not losing any anti-freeze. Could this be a failing MAP sensor (slow response)? What else could it be?

Friday, July 13th, 2012 AT 5:40 AM

3 Answers

  • Tiny
  • ASEMaster6371
  • Expert
  • 25,551 posts

Could cuase it to run rich, black smoke. If you have white from overheating, did you check the head for being cracked?

Roy

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Friday, July 13th, 2012 AT 11:43 AM
  • Tiny
  • wmika@frontiernet.net
  • Member

The original head was cracked so I'm very familiar with the smell of burning coolant. I replaced it with a reconditioned one. Engine temp. Is steady so it's not overheating. The smoke kind of smells like sulfur (fireworks) so I'm thinking it's running very rich coming off highway speed and the MAP sensor is reacting slowly and after a little time, responds correctly and the smoke stops.

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Friday, July 13th, 2012 AT 12:20 PM
  • Tiny
  • ASEMaster6371
  • Expert
  • 25,551 posts

Start with a compression test. Make sure the cylinders are good.

Have you replaced he basic components? Plugs, wires, coil?

What kind of vacuum do you have? Is it flutuating or steady and how much?

Was the cat ok before this repair?

Roy

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Friday, July 13th, 2012 AT 12:34 PM

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