code of PO171 erratic engine idle and serious engine vibration

2000 FORD WINDSTAR
150,000 MILES • 3.8L
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POPPASMURF
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  • 2 POSTS
engine runs rough from idle up to about 2500 rpm then smooths out a little bit. the check engine light does not come on. The intake manifold and gaskets, coil, plugs, plug wires, and fuel pressure regulator were replaced about four years ago. What it acts like is at least one cylinder is firing too soon. Thanks.
Mar 6, 2017 at 8:38 AM
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STRAILER
  • ✓ASE Certified Mechanic
  • 54,832 POSTS
  • ASE Certified Mechanic
Hello,

It sounds like you have a compression problem in one of the cylinders like a head gasket is blown between two cylinders. Please do a compression test and record each cylinder,

here is a guide to help you

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

Please let us know what you find so it will help others.

Best, Ken
Mar 8, 2017 at 12:18 PM
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