tng196664

Hello, I need help please. I have a 2003 silverado 5.3 ,,,random misfire cyl.3 left side . Verified coil is ok , good new plug wires, new plugs , fire from coil to wire, out of wire to bottom of plug . OK I know this might not be good to do or safe ,while engine is running I unplugged a couple of the injectors . Each one I unplugged there was a noticeable difference in idle other than the misfiring cylinder . I cleaned injectors and swapped one from a cylinder that was firing good . Still no fire on 3rd cylndr.Very little white on plug on misfiring cylinder. 204, miles . Changed knock sensors & intake gasket bout a month ago . Had misfire before that. Have tried spraying brake clnr .didn't find any leaks. I can smell antifreeze,not overheating. Again, had misfire b4 chnging snsrs and b4 smell of antifreeaze.

tech2

do a compression check

tng196664

Guys I'm really lost,,,help .? I borrowed a compression tester today . I saw 3 different ways to check . #1-instructions with gauge said with engine warm remove all plugs,,compare each cylinder by turning engine over. Watching needle increase 5 times/turns.only 60-75psi.... #2 said on one forum- the same way except turn over 7-8 times.120-140psi. #3 said turn engine over until needle stops going up .170-190psi. Either way I did it ,wrong or right each cyl. all stayed within about 10 or so psi. Here's total lost/confusion!!!? The 3rd cyl. left bank is where misfire is . It stayed good,no leak down or nothing . The 2nd cyl. same bank right beside 3rd slowly leaked down . Now what? Where do I go?? What's all this mean ?

tech2

I do six hits. the throttle should be held wide open when the engines cranking. the fuel injectors should be disabled so the fuel doesn't wash down the cylinder walls. disable the coils also. the battery should be fully charged. all plugs should be removed.
what the first hit. it should be 1/2 of the final pressure reading.