Question about 2003 Chevrolet TrailBlazer

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Yes i have a 1999 chevy suburban and i been having problems it keeps giving me codes of po301 and po172 so i replaced spark plugs wire cap rotor i replaced the post o2sensor on bank one tried haven the garage run a test to check out fuel pressure that was good also had them ckeck injectors they are fine checked volts on egr valve, maf,and all other sensors also tried filling gas up with 93 octane and running a can of sea foam through system and then tried to puting a half can of sea foam in with the oil just to see if the valve guides were gumed up after all this i still have not found out what the problem is anyone have info that might help fix this problem

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Check for injector "O" ring sealing issue. Not the first one of these I have heard of . The ring gets cut or damaged during assembly and over time as the ring hardens they develop a vacuum leak that causes the lean miss fire problem.
Also check the intake runner for leaking a cylinder head mating surface or vacuum accessory ports leaking.
A can of carb cleaner lightly sprayed at the injector and intake seal will change the idle quality if seal or gasket is bad.
Good luck, let me know.

Posted on Mar 04, 2009

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