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  1. CruelJung

    IAT Always Reads 32°

    Earlier this year, I solved a cold start issue with my 2008 Yukon XL (5.3 LMG) by replacing my ECT sensor. I discovered a few other issues along the way to that fix and one of those issues is that my intake air temperature consistently reads 32°, regardless of environmental conditions or engine...
  2. CruelJung

    Rough Idle @ Cold Crank (Worse in Cold Weather) + Fluctuating RPM in Drive

    SOLVED - Engine Coolant Temperature Sensor It's that rare time of year in my state, when the weather dips into cooler temperatures, which gave me the opportunity to test solutions again. Before replacing the ECT sensor, I swapped my MAF sensor for a new one to see if anything changed--nothing...
  3. CruelJung

    Rough Idle @ Cold Crank (Worse in Cold Weather) + Fluctuating RPM in Drive

    I see. The vacuum gauge was unchanging, unless PCM adjustments would be movements as small as a 64th to 16th of an inch--which I don't so much recall as I can imagine I would have thought unimportant at that time. Upstream O2 sensors are not old. I had those replaced (with Bosch models, I...
  4. CruelJung

    Upholstering SLT Door Panels To Match Denali Trim

    Can't help but agree with you. Considering the sheer amount of faux materials in these vehicles, though, I've come to accept the rubber/plastic parts for now. I think, unless I find a great deal on a set of Denali/Escalade panels for a swap, I'll hold out for a full upholstery job on all the...
  5. CruelJung

    Upholstering SLT Door Panels To Match Denali Trim

    I almost did that after finding some mint condition Escalade door panels that matched my color and panel style (07-09), but passed on the almost $900 purchase. I would have tried to negotiate a better price, but I still didn't think it was worth it considering where else that money could go...
  6. CruelJung

    Rough Idle @ Cold Crank (Worse in Cold Weather) + Fluctuating RPM in Drive

    I replaced the check valve to booster grommet (with one from a universal multi-pack I had on hand) and that corrected my STFTs the same way plugging the booster hose did. Afterwards, I purchased a new (genuine AC Delco) check valve and grommet and installed with no new improvements. It seems my...
  7. CruelJung

    Rough Idle @ Cold Crank (Worse in Cold Weather) + Fluctuating RPM in Drive

    I was hoping the white plastic swivel piece might be a quick fix (if that's the check valve), but I haven't done any further testing/searching since I vacuum tested last night. In the video, it looks like it can pop right out of the booster, so it's likely a cheap buy if available separately...
  8. CruelJung

    Rough Idle @ Cold Crank (Worse in Cold Weather) + Fluctuating RPM in Drive

    The spark plugs and wires are 2 years and just under 30k miles old. I don't have the exact part information on file, but my mechanic will only use OEM parts for repairs--aside from performance upgrades--so I have no doubt they are true AC Delco. As far as the iridium aspect, I'm not sure unless...
  9. CruelJung

    Rough Idle @ Cold Crank (Worse in Cold Weather) + Fluctuating RPM in Drive

    I ran a vacuum test on the brake booster hose and attached images of my scan tool data. STFTs seem right with the hose plugged and I'm thinking the LTFTs are likely deep in the negative numbers per the ECM trying to reconfigure with the leak absent. I presume that after the booster is replaced...
  10. CruelJung

    Rough Idle @ Cold Crank (Worse in Cold Weather) + Fluctuating RPM in Drive

    Thanks! I've included some screenshots of my video recording below; the results line up with your description. More on that to follow. Okay, that's what I've seen on all the displacements in videos explaining the replacement process--with the implication being the ones removed are 'factory.' I...
  11. CruelJung

    Rough Idle @ Cold Crank (Worse in Cold Weather) + Fluctuating RPM in Drive

    I would be happy to find the intake gaskets are not the source. Mine do have a metal framework around them, which seems to indicate they are not original? I don't recall the color of the actual seals within the framework (I want to say I could see a bit of teal), but I can post an image if that...
  12. CruelJung

    Rough Idle @ Cold Crank (Worse in Cold Weather) + Fluctuating RPM in Drive

    I know the spark plugs and wires are AC Delco, and I suspect but have not yet confirmed if the intake gaskets were done when the AFM was deleted--I would expect they were, though, since the valley plate had to be removed. Is there any superficial observation I could make to determine if the...
  13. CruelJung

    Rough Idle @ Cold Crank (Worse in Cold Weather) + Fluctuating RPM in Drive

    I have seen other posts about similar issues to what I'm experiencing, but I haven't been able to glean any solutions from them as of yet. However, I've been doing what I can and collecting information over the past month, so hopefully the process of elimination has a head-start. Issue In...
    • CruelJung
    • Thread
    • cold start cold weather diablo predator 2 p0171 p0174 p0300 rough idle
    • Replies: 23
    • Forum: Engine & Drivetrain
  14. CruelJung

    2008 5.3 Engine Oil/Filter + Octane Rating

    I thought it would be good to close this out with some install images and an update: All things considered, everything went well. I did this in early January and haven't experienced any oil or vacuum leaks resulting from the install. Oil loss is still occurring, due to the pre-existing...
  15. CruelJung

    2008 5.3 Engine Oil/Filter + Octane Rating

    That's encouraging, thanks! My OCC (Moroso #85481) and valve cover (OEM #12570427) are on the way, so that will be the beginning. Once those aspects are finished I'll be moving on to the upper engine investigations. Thanks for the links! I'll definitely plan for a thread. Something else I...
  16. CruelJung

    2008 5.3 Engine Oil/Filter + Octane Rating

    Thank you for all the links and information! It's definitely good to know the experience of someone who uses or has used the same product. I made my first Amsoil purchase from a local dealer (different than my current) and even he told me 4-5k was an ideal OCI, as he was a high mileage Suburban...
  17. CruelJung

    2008 5.3 Engine Oil/Filter + Octane Rating

    Thank you! It's too bad I can't determine which valve cover I have with certainty unless I remove it. I suppose if find that my cover is already updated, then I may very well have to perform this piston soak. In a similar vein, I would be pleased to source the oil leak back to my oil pressure...
  18. CruelJung

    2008 5.3 Engine Oil/Filter + Octane Rating

    I've only heard good things about Wix, so far, and I can't say Wix is responsible for whatever caused my filter to leak that one time. The reason I switched to Amsoil (oil and filter) is because of the reviews I had seen and the personal experiences of some people close to me. The reason why...
  19. CruelJung

    2008 5.3 Engine Oil/Filter + Octane Rating

    Well, that's great! It's certainly been a positive experience so far and, for my first major dive into automotive work, this community has been a gold mine. Right. I've been mulling a few over since our initial conversation and I don't mind paying for the convenience, peace of mind, and...
  20. CruelJung

    2008 5.3 Engine Oil/Filter + Octane Rating

    When the leak was first discovered--before I noticed the oily filter and created this thread--I checked that plate in the hope of it being the problem and not my rear main seal; unfortunately, no leak there. Also, the leaky oil filter was a one-off. I kept that filter and plan to open it to...
  21. CruelJung

    2008 5.3 Engine Oil/Filter + Octane Rating

    Thanks so much for responding to this late reply. I appreciate the advice and personal experience. I've been holding off on these engine components while trying to absorb as much information as possible, since I'm a novice in these areas, but it hasn't been for a lack of desire to do the work...
  22. CruelJung

    Thinking of Buying a 07-14 NNBS Tahoe/Suburban? Look Here

    I had this issue with my front driver side door. I wrapped yellow pipe thread tape around the top of the rod before re-installing the lock knob and that solved the problem for me--figured it was the plastic knob components rattling on the metal rod internally, rather than the lock knob rattling...
  23. CruelJung

    2008 5.3 Engine Oil/Filter + Octane Rating

    I have quite a few questions, really, and background information to add to the questions. All of the replies to this thread were great, but I was new to most of these concepts and especially unfamiliar with engine modifications when making the initial post. That being said, I have at least a...
  24. CruelJung

    2008 5.3 Engine Oil/Filter + Octane Rating

    Based upon that description, I don't think my engine is experiencing any spark knock with any of the octane ratings I've tried now (87, 89, 91, and 93). In fact, I recently added a fuel system cleaner (Amsoil PI) when filling my tank and that recurrent noise I described earlier seems to have...
  25. CruelJung

    2008 5.3 Engine Oil/Filter + Octane Rating

    I just filled up with 93 to see if the engine ran differently and, while it could just be a placebo effect, the engine seems to run a bit more smoothly than before. On the note of 'knock,' I have had a rumble/rattle sound since I acquired the vehicle that seemed to occur on regular, looped...

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