will not run smoothly

2003 CHEVROLET SILVERADO
180,000 MILES • 4.3L • V6 • 2WD • AUTOMATIC
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JOHNNY COLLINS
  • MEMBER
  • 1 POST
Truck stopped running while driving down the road, towed it home. put a complete tune up on it still idle bad a buddy came over and scanned it he said that the crankshaft sensor was bad.I replaced it still will not idle smoothly. Why?
May 15, 2017 at 6:29 AM
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HMAC300
  • ✓Experienced Mechanic
  • 48,601 POSTS
try cleaning throttle plate on both sides and IAC hole with choke cleaner. this may be an injector problem as GM changed a lot of them due to poor running qualities. also check for a vacuum leak. like hoses. o-ring leaks around plenum and scan for codes.
May 15, 2017 at 8:48 AM
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STRAILER
  • ✓Experienced Mechanic
  • 55,673 POSTS
Hello,

If the rough idle seems to be consistent then I would do a compression test to see if you have one low cylinder.

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

Please run this test and get back to us so we can continue helping you.

Cheers, Ken
May 18, 2017 at 3:56 AM
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