2003 silverado 83000 miles , has a miss ,

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2003 silverado 5.3 83000 miles , has a miss , code shows #3 missfire , changed coil , still a miss , swapped plug and wires from another cyl , still missing , not sure if miss switched over , probly due for a little tlc since plugs and wires are original, plugs and wires dont look too bad
what say the general diyers out there ?
 
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Compression check?
Any valvetrain noise?
no , always ran good , dont drive much , garage queen, just took it out saturday to pick up tranny fluid for car and started missing , pulled up a 303 code
 
2003 silverado 5.3 83000 miles , has a miss , code shows #3 missfire , changed coil , still a miss , swapped plug and wires from another cyl , still missing , not sure if miss switched over , probly due for a little tlc since plugs and wires are original, plugs and wires dont look too bad
what say the general diyers out there ?
Why not??

I feel like this information you need before more shots from the parts cannon
 
What kind of scanner do you have? I mean, can you do some real time monitoring? or is the plan to just clear and see if the miss error code pops up on a different cylinder after a while, after moving plug and wire to a different cylinder?
 
What kind of scanner do you have? I mean, can you do some real time monitoring? or is the plan to just clear and see if the miss error code pops up on a different cylinder after a while, after moving plug and wire to a different cylinder?
i dont have means to do some real time monitoring , i can read codes and thats it
 
Could be injector, that is what happened on my 2000 LS1 WS6, very similar setup as truck 5.3.

You really need a better scanner so you can see if the miss moved.
 
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How old is the fuel in the tank?

If the gas is kinda old, and you cranked it a few seconds without it firing, then cranked again, it could have made the plug wet giving you a misfire. Yours may crank till it starts when the starter is engaged so may not pertain.

If it's a steady miss, could be a coil pack.

Check for chewed wires from rodent damage.

Just a few ideas.
 
I was going to suggest a full tune up to start with and then check that cylinders coil pack if the issue still persisted. I have a 2004 GMC w/ 5.3 120k miles and it runs great just need to replace those knock sensors and the harness. Mine has been great but it's always the common problems that show their ugly faces.
 
I was going to suggest a full tune up to start with and then check that cylinders coil pack if the issue still persisted. I have a 2004 GMC w/ 5.3 120k miles and it runs great just need to replace those knock sensors and the harness. Mine has been great but it's always the common problems that show their ugly faces.
I have 244k on my 05 and the knock sensors and intake gaskets have still yet to fail. Any symptoms that they could show prior to getting a code or completely failing? I keep an eye on long term fuel trims for intake gasket failure, but not sure about knock sensors.
 
2003 silverado 5.3 83000 miles , has a miss , code shows #3 missfire , changed coil , still a miss , swapped plug and wires from another cyl , still missing , not sure if miss switched over , probly due for a little tlc since plugs and wires are original, plugs and wires dont look too bad
what say the general diyers out there ?
if you switch the parts with another cylinder, and the code and misfire return on the new cylinder, then it isone of the parts you switched. If the code stays in the same spot, the issue is likely electrical in coil wiring or injector wiring.
 
I have 244k on my 05 and the knock sensors and intake gaskets have still yet to fail. Any symptoms that they could show prior to getting a code or completely failing? I keep an eye on long term fuel trims for intake gasket failure, but not sure about knock sensors.
Sadly no, they failed pretty much without warning but typical running rough and the inevitable cel and is a very common problem on these. I haven't washed the engine but most people say to not do that because there is a foam piece underneath that traps water in there and causes them to fail, most times when reassembling they leave that piece out. I have all the parts to do it just waiting for the funds which will be this fall but I've been running it the last few years as is. I want to have the coolant flushed and replace all the hoses because it's practically 20 yrs old now.
 
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