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Showing results for tags 'knock retard'.
Hey yall! New member here, sorry for creating a thread so early on, but my warranty expiration is creeping up on me fast and I need to get this sorted- so here's my issue. I have a 2015 2500HD with the 6.0 and about 95,000mi, and for the past 6 months, I've been having this issue where It'd start pulling timing ( up to 15 degrees of KR) under moderate to heavy throttle, as soon as it hits 3000RPM. There is no audible knock, but 15 degrees of KR sounds very excessive. Higher octane fuel makes the issue better, and usually after long interstate drives (no heatsoak), it runs great, but generally, it's very bad. Towing a 32FT trailer full of band equipment up a mild hill, it struggles to get out of first gear, and slams into the next gear because the timing is so far retarded before the shift, that it screws with the shift timing. I have used various fuel system cleaners ( now trying Amsoil Pi, as I know its well proven ) but so far, none have made any difference. I want to check the fuel pressure, but I don't see a test port, and I can't get any OBD app to display fuel pressure. Here's what confuses me: Sometimes, under the same conditions, It'll run just fine and pull hard straight through 3000 RPM. The only thing I can find different between the times that it runs like a POS and times that it runs like its brand new, is that when it's running like crap, it shudders at idle- enough to be felt throughout the entire truck. It pulls the most timing at around 3000, and tapers down as the revs increase. I got it used, with about 76,000mi, so I'm not clear about its past. Back when it was running horribly I was considering that It might have been tuned by the previous owner, but lately, its been randomly running just fine. Its been fine for the past week or so, but I'm still very curious about what could be going on. I have TorquePRO recordings of the issue happening, which I may upload later if that would be of any help. I've been hoping for a CEL but of course- no pending or stored codes! Thank you all! Sorry for the length of the post!