Joegr and other LS guru I need assistance

[Diplomat 1]

If you haven't seen my other thread I have a 2003 LS v8 with codes 308 and 316. All plugs and coils have been replaced with motorcraft parts. I have swapped coils and plugs and still cylinder 8 has the misfire. I did a compression check and have good compression all around. I put a noid light on the fuel injector connector and it works. I tested for spark with a tester and see spark. Now I'm stumped. I was thinking maybe timing but someone said timing is set by computer. Here is a video of the misfire.



Does it sound like motor knocking? What other possibilities could cause it to misfire if I have spark fuel and compression? Could a clogged cat cause this? I am very confused please need major help frm you guys. Thanks

 

[joegr]

Well, I'd say bad fuel injector, but that wouldn't explain the noise. I have no good idea.

 

[Diplomat 1]

I forgot to mention I just changed the fuel injector on cylinder 8 also. I feel like I have checked everything (spark fuel compression and air) but still have a misfire. I really am hoping motor isn't shot but before I do condem the motor I like to be sure. What should my next step be? Cylinder leak down?

 

[joegr]

Yes, I think the leak-down test and internal inspections are what is left.

 

[04_Sport_LS]

Bad cam follower/tappet???

 

[04_Sport_LS]

I feel like I have checked everything (spark fuel compression and air) but still have a misfire.

Did you actually do a compresion test? Both dry and wet... with a compresion gauge??? Sticking a finger in the spark plug hole isn't a true compression test. The video/audio was hard to listen to through my laptop,,, but i thought I heard a couple of different noises.

I heard the "lope", (putt, putt), of the missing cylinder,,, but I also thought i heard some sort of ticking or rattle. While Joe is not incorrect to suggest a "leak down" test of the cylinder in question... I think you may want to pull the valve cover on the suspect side of the engine,,, and observe and feel any and all moving parts... to see if something is "loose".

Pull at least the fuel pump fuse,,, so the engine doesn't start. Then look and feel for something that doesn't seem right on cyl #8... while the engine is "cranked". To me,,, the sound seems more mechanical,,, but not directly valve related. Somewhere in between the cam and valves.

In past research on my part... you may have an isue with the VVT/VCT cam phaser. More of a problem with the passenger side than the drivers side... but if milage and ownership unknown on your part... then anything is possible at this point