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  1. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    I’ll keep an eye on the misfires. With as many miles as this truck has, I know there will always be more work that can be done but I’m just trying to keep it reliable. Probably could use a new set of plugs and a fresh air filter too, and a maf cleaning. I’ll drive it like this through the...
  2. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    From 15 minute drive today. CMP retard and ignition timing advance are averages
  3. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    Ok so upon further review, my CMP retard was about -9.5 degrees. Loosened distributor a little, rotated it counter clockwise until the reading was about -0.5 at a little over 1000rpm and then tightened it down. This means everything should be good to go, right? truck runs better now than it...
  4. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    I looked again. Dashcommand for iOS is $10, then extended parameters are $10. The problem was dark mode. When I clicked on GM it was just blank, or so I thought. Just had to click through the lines to see what they are.
  5. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    Can you point me in the right direction on that? I cannot find a PID for this.
  6. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    Good to know, thank you for your input. May be worth the effort to shop around mechanics in the area for one that knows about timing these engines.
  7. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    I think that one is -2 to +2 degrees, but again I am no expert and I’m hoping I don’t need to be. From the looks of it, it doesn’t take a rocket scientist to put a distributor back in after all.
  8. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    Quick update for anyone in the future that cares to know this: Only check engine light I got today was P0158 for a known faulty post-cat O2 sensor (no big deal but I want to fix that, too). Everything else looks to be on the up and up, and truck runs beautifully. Calculated about 17mpg on a...
  9. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    Stabbed back in, all reassembled and purrs like a kitten. I'll be back with some data logs for a follow up, but I'm very pleased with the results. No CEL after 3 startups. Timing advance for #1 still seems high, about 20-25 usually while underway. Anyone know what this is about? Normal?
  10. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    The log was taken on my drive to work. No surge really noticeable, worst I could say I noticed was a rough idle. But by rough, it was really pretty consistent just a good amount of vibration consistently. Part of my problem might be that it’s been this way ever since I got it with over 200k...
  11. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    Update: Opened it up for intake gaskets today. Not as bad as I expected, and not in the places I expected but you can see where #4 was sagging. These were aftermarket FelPro gaskets but they were not the metal ones, just plastic. Broken in several places. The set I am installing is much more...
  12. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    Tested each injector circuit at the harness with a multimeter, 12V at each one during crank. It's an ugly mess in there and it's hard to believe it's not the problem but I don't think it is. The thing that's most frustrating is that it seems to run fine, or as fine as it ever has for me...
  13. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    So did a little more digging this morning. Pulled the #4 plug to check for rust, seems reasonable that if the manifold gasket was leaking that there would be some slight rusting or moisture present on the plug after sitting overnight. Dry as a bone. No fuel odor present at all. I can't stop...
  14. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    Yeah sorry for that, I copy pasted the list from the list I use to keep track of everything (edit: removed the irrelevant ones). I don’t know about head or intake gaskets. I haven’t done them but at 250k miles they *must* have been replaced by now. Wasn’t the problem with the originals from the...
  15. THerm

    SOLVED: 98 K1500 5.7L Vortec random misfire P0300 P030x

    Hello everyone, I'm hoping to get some help with my truck. It's been a great beater and I'm hoping to keep it running for at least a few more years. Currently, it has ~240,000 miles on it. For starters, here's the list of things I've replaced since I've had it: Part Replaced plugs 2018 wires...

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