I have a 2005 1500 with the 5.7L Hemi. I'm getting random misfires. I changed all 16 plugs but the issue didn't improve. I had a shop look at it and said there was a crack in my intake manifold. After changing that it's still misfiring. They said there was a lot of sludge they noticed when changing the manifold. They also ran a compression test and say one of the lifters is sticking which is causing a valve to stay open. Can sludge really cause all this? I kinda feel like they are giving me the run around. Any thoughts?

 

Really need help here. The shop had it all week and still say its sludge and carbon build up. They say I need to replace all the lifters. This just doesn't seem right to me. Any ideas???

 

Sludge will easily cause this.
What did the compression test say?
Are all the coils getting the same-ish volts?

 

Not sure of the specifics on the compression test. They just told me at first it was the lifter in cylinder 3 but now it's multiple lifters that are sticking. It only misfires when the engine is cold so I guess sludge could really be the issue. I'm just not sure what my next step should be. Is there a way to get rid of sludge? I've only had the truck for about 10 months and only put 4k miles on it. They said they flushed the engine about 5 times and put multiple fuel cleaners in but nothing changed. I don't have the time or money to keep guessing with this. Just wanna pinpoint the issue and fix it.

 

Try running some seafoam through the vacuum line, it might help with the sticky lifter. Can't hurt.

 

Yeah, google sea foam, they have some good vids and instructions on their website for how to use it to clean you engine. Also some threads on here about using marvel mystery oil in your oil, amount etc. like adding to your oil, running 300 miles or so, then do an oil change.

 

Change your 02 sensors. Mine kept throwing a misfire code. I watched the voltage drop out on 1 of my upstream sensors when given slight throttle.

 

sluge build up comes from lac of oil changes and yes can cause a lot of head achs on internal engine componets.try the sea foam and some injector cleaner when i do a tune up lucas injector cleaner is part of the tune up

 

I agree with you on changing o2 sensors for a misfire, but for his lifter Seafoam would help, some people even use marvel mystrey oil

 

Im a firm believer in Marvel Mystery oil. I use it in everything. Im just assuming that the shop hes taking it to sucks because they also told him fixing his leaking manifold would fix the problem. And unless I saw them diagnose the sticking lifter with my own eyes I wouldn't believe them. A stuck lifter is going to cause more problems than a "random" misfire.