No spak at cylinder #4

[Billyd7795]

Hey, I am new to the forum. I have a 2008 yukon that is misfiring and giving me a P0300 code. I have replaced all spark plugs, coil packs and wires, still have misfire. I have done a spark test on all cylinders and I have no spark at cylinder 4 still. I don't know where to go from here any advice is appreciated.

 

[Tonyv__]

Hey, I am new to the forum. I have a 2008 yukon that is misfiring and giving me a P0300 code. I have replaced all spark plugs, coil packs and wires, still have misfire. I have done a spark test on all cylinders and I have no spark at cylinder 4 still. I don't know where to go from here any advice is appreciated.

Disregard my comment… I skimmed over the part where you replaced coil packs

 

[Trey Hardy]

Hey, I am new to the forum. I have a 2008 yukon that is misfiring and giving me a P0300 code. I have replaced all spark plugs, coil packs and wires, still have misfire. I have done a spark test on all cylinders and I have no spark at cylinder 4 still. I don't know where to go from here any advice is appreciated.

I’m having the same issue I’ve changed 02 sensors spark plugs coil packs wires gaskets evap and all vent lines with no luck I’m thinking I have a chaffed wire somewhere

 

[Doubeleive]

Hey, I am new to the forum. I have a 2008 yukon that is misfiring and giving me a P0300 code. I have replaced all spark plugs, coil packs and wires, still have misfire. I have done a spark test on all cylinders and I have no spark at cylinder 4 still. I don't know where to go from here any advice is appreciated.

going to have to trace the cylinder 4 coil wire to wherever the break is

 

[Fless]

Just a generic P0300 code? Seems like a #4 misfire would trigger a P0304. How have you determined there's no spark? Does the ECM have control?

Look at individual cylinder misfire counts if you have a scanner that can do that, to confirm.

A P0300 can be caused by a crank-cam mis-sync; for that a CASE relearn can be done (if you can do one, do it to rule it out).

The link below has a diagnostic procedure, but use the links at the top of the browser window to make sure you're looking at the correct vehicle and engine.

P0304 — 2008 GMC Yukon 2WD V8-5.3L Service Manual | Operation CHARM

Detailed repair manual for the 2008 GMC Yukon 2WD V8-5.3L.

charm.li

 

[j91z28d1]

check for power at the coil plug

 

[Billyd7795]

Just a generic P0300 code? Seems like a #4 misfire would trigger a P0304. How have you determined there's no spark? Does the ECM have control?

Look at individual cylinder misfire counts if you have a scanner that can do that, to confirm.

A P0300 can be caused by a crank-cam mis-sync; for that a CASE relearn can be done (if you can do one, do it to rule it out).

The link below has a diagnostic procedure, but use the links at the top of the browser window to make sure you're looking at the correct vehicle and engine.

P0304 — 2008 GMC Yukon 2WD V8-5.3L Service Manual | Operation CHARM

Detailed repair manual for the 2008 GMC Yukon 2WD V8-5.3L.

charm.li

Just a generic P0300 code? Seems like a #4 misfire would trigger a P0304. How have you determined there's no spark? Does the ECM have control?

Look at individual cylinder misfire counts if you have a scanner that can do that, to confirm.

A P0300 can be caused by a crank-cam mis-sync; for that a CASE relearn can be done (if you can do one, do it to rule it out).

The link below has a diagnostic procedure, but use the links at the top of the browser window to make sure you're looking at the correct vehicle and engine.

https://charm.li/GMC/2008/Yukon 2WD...ting and Inspection/P Code Charts/P0304/[/URL

http://

Just a generic P0300 code? Seems like a #4 misfire would trigger a P0304. How have you determined there's no spark? Does the ECM have control?

Look at individual cylinder misfire counts if you have a scanner that can do that, to confirm.

A P0300 can be caused by a crank-cam mis-sync; for that a CASE relearn can be done (if you can do one, do it to rule it out).

The link below has a diagnostic procedure, but use the links at the top of the browser window to make sure you're looking at the correct vehicle and engine.

P0304 — 2008 GMC Yukon 2WD V8-5.3L Service Manual | Operation CHARM

Detailed repair manual for the 2008 GMC Yukon 2WD V8-5.3L.

charm.li

I don't have a scanner tool, I have taken it to Oriellys and Autozone for the scanner they have hoping to get a specific cylinder. I found cylinder 4 when I attached wire to each coil pack and took a ground wire to check for spark at each one # 4 was the only one with no spark. I have now traced the wire from that plug back to the connector and the all have no breaks. Did continuity test with my meter. Thank you for the information you have provided any other advice or tips would be greatly appreciated.