2002 Cadillac Escalade PO 307 MISFIRE PROBLEMS

  • V8
  • AWD
  • 11,600 MILES
Ok I am a technician on Electrical Motors and know some things about vehicles. I have a OBD and did a test and came up po307 misfire on #7. I took it to a Chevy dealer. They told me it was a fuel pump low pressure. I didnt believe them but put the fuel pump on anyhow. I still have a po307. I decided to change all plug wires and Platinum Plugs with GM recommended plugs. I still have PO307. Today I changed the coil 7 with 5 and problem satyed with 7. I also noticed number 7 plug is very wet and fouled looking every time I change it. I went as far as tracing out wires to the injector and they are fine. I also ohmed the injector came back with 16-17 ohms just like the injector next to it. I am going nuts. I do not want to drive the truck running rough like this and am getting sick of paying mechanics to throw parts at it. Mileage is also down to 10 mpg. Do you think the injector is stuck open on #7. Is there any way to check this injector? I also pulled the plug wirte and put a different plug on it and layed on exhaust manifold. It does have spark.

i repaired it. Was and in injector cleaned with gumout runs great now!
Do you
have the same problem?
Thursday, May 28th, 2009 AT 4:38 PM

1 Reply

Listen to the injector with a stethoscope, long screwdriver, or other long rod, and compare it with another. It should make a metallic clicking. Check the fuel pressure, if at rest it drops off almost immediately that could indicate a leaking injector. Check the compression on #7 and compare with another. Does it crank evenly, or sound uneven that could indicate a compression loss. Are you using coolant?
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Friday, May 29th, 2009 AT 10:33 PM

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