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My mechanic is stumped

Tiny
MHILLING
  • MEMBER
  • 2003 CHEVROLET SILVERADO
  • 47,000 MILES
OK here is the problem. On my 2003 silver auto with the 4.7 I'm getting constant misfire only on cylinders #4 & #6. Had the coils, plugs, and wires replaced. Didn't fix it. Had the injectors replaced. Didn't fix it. Had the computer replaced. Didn't fix it. Had a compression test done, everything is good. Checked for vacuum leaks, there are none. Checked fuel pressures, they are fine. Replaced fuel filter. Still looking into it and I will update everything done to it.

Need some ideas on where to look next
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Tuesday, January 24th, 2012 AT 5:31 AM

3 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check for vacuum leak and also the crankshaft position sensor-
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Tuesday, January 24th, 2012 AT 5:42 AM
Tiny
JACKSPRAT
  • MEMBER
  • 46 POSTS
Check wiring harness between injectors and ECU, if your mechanic has an oscilloscope he can check the injector activation.
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Tuesday, January 24th, 2012 AT 9:41 AM
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Vacuum leaks and a continuity test for the injector wires.
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Tuesday, January 24th, 2012 AT 9:48 PM

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