1998 GMC Sierra P0306

  • 1 POST
  • 1998 GMC SIERRA

Engine Performance problem
1998 GMC Sierra V8 Four Wheel Drive Automatic 130000 miles

I am @ my wits end. I have a dead hole in my 5.0 engine. I pull a p0306, cylinder 6, misfire. I have changed the cap, rotor and plugs, spider assembly, upper and lower intake gaskets, the cmp sensor, the Bank 1 sensor 2 O2 sensor, the bank 2 sensor 1 sensor, ECM, and a new fuel pump/module is on the way.
I have done some limited scans, and bank 2 fuel trims are rich, still, even after gasket change on lower intake. I did find #2 intake runner gasket was bad, along with front coolant port. I have done a vacuum test around 13# steady. Did compression test and running compression test, found nothing out of the ordinary. However fuel pressure immediately drops, when fuel pump stops running with key on engine off. I have traced the pump to be leaking(pinched both fuel lines, only than does pressure hold). However unsure why is only picking on bank 2 cylinder 6 edpecially. I pulled banks 2 plugs. All are black, EXCEPT CYLINDER 6? Cylinder 6 is still whitish, with minimal black. This truck only has 1 coil, for all 8 cylinders, why is 6 a problem, when static, and running compression is still in range with all ojer cylinders?

This is a fiend's truck, I did also find MAF sensor in backwards, I did clean it, install correctly. However also only getting 8.4 g/s on scans. I am going nuts here, what am I overlooking?

Do you
have the same problem?
Wednesday, May 27th, 2009 AT 2:30 PM

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