Hey! I’ve got a 2009 Jeep Grand Cherokee 5.7 with about 82,000 miles (I’ve had it for about 20k miles and 2 years) and I’m losing my mind trying to figure out what’s going on. I’ve been having an issue with an intermittent rough idle for months as well as a rare stall out at stops and a bit of hesitation in higher RPMS if I floor it. Ive had it at 3 different places including the stealership and nobody can tell me what is going on as i’m not throwing any codes and apparently none of these guys know how to read live data. The only aftermarket mod I have is an aftermarket intake. Spark plugs were put in when I bought this thing and I’ve checked them, they look brand new. I’ve tried using a propane torch to find vac leaks to no avail. I did test my EVAP purge valve with a vac pump and it wasn’t holding vacuum pressure so I swapped that out a month ago and reset the ECU and this did calm the idle down a noticeable amount and I haven’t stalled out since but I’m still having ongoing issues. I did purchase an Autel OBD dongle to grab some live data with my phone. Any insight you can give would be much appreciated!
Pull off a valve cover and have someone turn it over. Watch the movement of the rocker arms. If they don't all move the same, you have the now famous bad hydraulic roller lifters that are eating the cam and need to be replaced along with the cam. This requires pulling the heads.
Ugh… I’ve done a head gasket on an old 4 banger S-10 and cams on an SOHC mustang GT but that might be more of a project then I’m willing to take on… I’m just curious, Doc… is it the wacky live data that leads you to believe that? I don’t really know that much about it but the timing being all over the place and having both positive and negative fuel trims seemed kinda odd intuitively…
All I'm saying is this is a common problem with hemis and it's easy to check out and eliminate as a possibility (hopefully).
Fair enough, I’ll see if I can check it out this weekend. Thanks!
Pulled a valve cover. Not sure I see anything obvious
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