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Discussion Starter · #1 ·
2013 LR4 - 137k miles - 5.0 Engine (owned for about 100k miles, with no engine-related issues until now)

Recent History:
  • A few weeks back it busted the dreaded crossover pipe (front one). Replaced it along with water pump and thermostat. (don't believe it ever ran hot for long at all)
  • After that repair, I thought all was good, then it started misfiring, mostly on Bank 1. Tried some sub-par injection cleaning before I heard about the BG44K which I have now, but haven't yet been able to use. And then I replaced the original spark plugs with the OEM Laser Iridium NGKs.

Misfires seemed to be fixed and all was good... until it runs for about... 30 minutes to an hour and then BOOM. Misfires and here comes the rising temps. And now, the misfires are exclusively on Bank 1. (2, 4, 6, and 8) If I was just idling in the driveway, I think it would run all day long, but driving around a bit, and at some point, it goes into this misfire mode with the Restricted Performance. I was afraid of blown head gaskets, of course, but I've only had one puff of white smoke out of my tail pipe, ever. Other than that, temps are maintained perfectly, drives perfectly, everything great until it's not. I have not done a block test yet, and perhaps I need to, but it doesn't seem like blown HG's to me.

Things I've investigated and know from the GAP tool so far:

-Fuel rail pressure comes up to the 2175 on the dot during cold start high idle, and it seems correct at most times, but before starting,I think the LPFP is maybe weak, because I've never seen it higher than around 65psi before cranking. I don't know if that would lead to any issue, because it never has any trouble cranking, and once cranked the HPFP seem ok most of the time I'm looking at the live data. Sensors appear to be in the healthy voltage range as well.

-Actual VVT position on the Exhaust banks look ok. Very close to 120 (118-121) while idling, but Intake banks look a bit strange to me. While Bank 2 maintains around 72.5-74.5, Bank 1 is consistently a bit higher at 74.5 to 76.5.

-Fuel injectors show the same signals for all 8 cyl.

-Probably unrelated, but despite running it for hours and blasting full heat on both front and rear AC's, I cannot for the life of me get the last bits of air out of the coolant system in order to get the rear AC to blow hot air. I think I may have what I need to do the vauum pump thing, but haven't fully investigated how to do it. I've just been bleeding and bleeding, and topping off, and bleeding and bleeding, both bleeds... I'll park with front way up, bleed, top, bleed top, run.... park flat, repeat.... what is wrong with this dang thing and the coolant flow?

So, there we are. I need this thing reliable for my wife, and can't have it randomly going into this restricted performance mode and heating up.

Thank you for any and all suggestions/help!
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