my mechanic is stumped

2003 CHEVROLET SILVERADO
47,000 MILES
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MHILLING
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  • 1 POST
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
Jan 24, 2012 at 5:31 AM
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RASMATAZ
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Check for vacuum leak and also the crankshaft position sensor-
Jan 24, 2012 at 5:42 AM
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JACKSPRAT
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  • 46 POSTS
check wiring harness between injectors and ECU ,if your mechanic has an oscilloscope he can check the injector activation.
Jan 24, 2012 at 9:41 AM
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MHPAUTOS
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vacuum leaks and a continuity test for the injector wires.
Jan 24, 2012 at 9:48 PM