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  1. John03Z71

    Help diagnosing two issues 1) misfiring/stumbling 2) coolant loss

    Thanks for all the replies. I haven’t had much time to focus on this since the holidays, but the misfiring / hesitation issue reared its ugly head last night by finally throwing a P0301 code, and it got realllllly bad during one acceleration period that caused the check engine light to start...
  2. John03Z71

    Help diagnosing two issues 1) misfiring/stumbling 2) coolant loss

    Thanks! I was going to pick up a can of cleaner from the parts store and try that. If that doesn't work, I'll swap the part out and see if that makes any difference. How much would you want for yours that you say is still in working order? Feel free to PM me.
  3. John03Z71

    Help diagnosing two issues 1) misfiring/stumbling 2) coolant loss

    Thanks for the info. Wouldn't the MAF throw a check engine light and code? I just took the oil filler cap off and besides some slight oil residue it's dry, no milky snotty stuff.
  4. John03Z71

    Help diagnosing two issues 1) misfiring/stumbling 2) coolant loss

    Thanks for the feedback. I'm doing some research to see if it's legal in my state (NC) to remove the cats, or if I have to replace them. Would much rather just cut them out but we have yearly emissions inspections.
  5. John03Z71

    Help diagnosing two issues 1) misfiring/stumbling 2) coolant loss

    My 2003 Tahoe 5.3 has about 270k miles. For the past year or two there has been a slight misfiring / hesitation on acceleration that has gotten progressively worse. Over this time period, I've replaced (not just due to this issue) plugs and wires, intake manifold gaskets, knock sensors, valve...
  6. John03Z71

    Misfires and Sputtering on acceleration

    Thanks for the reply. I just scanned for codes a few different times and all of them returned 0 stored codes. Misfire monitor "OK". I just took a quick look and did notice the very small vacuum line from the fuel pressure regulator has a little crack in the rubber boot at the top...
  7. John03Z71

    Misfires and Sputtering on acceleration

    About 10 days ago I replaced the knock sensors on my '03 Tahoe Z71, and replaced the intake manifold gasket while I had it off with a genuine Fel-Pro gasket. After I put everything back together and took it for a quick test drive down the street and back, I could immediately feel an increase in...
  8. John03Z71

    Help me find this oil leak please!

    Apparently the PCV system varies on different year models from my understanding... but on my '03, I literally pulled the vacuum hose straight up and off the valve cover gasket (rear of engine on driver's side). My PCV valve came off with the hose, all I had to do was pull the old one out and...
  9. John03Z71

    Help me find this oil leak please!

    Forgive my ignorance but can you please explain a bit more about exactly where / what I should look at? The oil leaks have slowed down considerably since I replaced the PCV valve... BUT I'm still getting "Check Oil Level" message on the dash once a week or so (which is about 300-400 miles or...
  10. John03Z71

    Help me find this oil leak please!

    Yes I just pulled the vacuum hose off the valve cover (drivers side rear of engine). The PCV valve is in the end of that hose. I was able to pull the old one off with just my hands and a little elbow grease... put the new one in, then popped the hose w/ new PCV valve back in the top of the...
  11. John03Z71

    Help me find this oil leak please!

    Thanks for this suggestion (and the previous). I checked the PCV valve today and the bottom side of the fat end (facing down into valve cover) had a very thick layer of hard residue buildup that was definitely blocking the hole, it was caked on so thick that when I sat it down on the ground it...
  12. John03Z71

    Help me find this oil leak please!

    Last night after swapping out my O2 sensor I spent a little time trying to figure out where the oil leak(s) is coming from. I started the engine and crawled underneath for several minutes watching for drips. I found that there is an area above that O2 sensor (bank 1, sensor 1 - driver's side...
  13. John03Z71

    Help me find this oil leak please!

    Reviving this thread from almost exactly a year ago, as my leaks never completely went away and now it's quite bad again. I'm losing about a quart of oil per week now (about 250 miles +/-). Seems to be more in the front of the engine this time as everything up front is soaked in oil, and I...
  14. John03Z71

    Check engine scan tool, quick question...

    Thanks, I’ll replace the O2 sensor. As for the fuel level sensor about 6 mos ago it started giving me problems, once I get down to half a tank or so it bounces back and forth from empty to 1/4. My current fuel gauge is via personal trip gallons used lol, reset at each fill up. Just hoping that...
  15. John03Z71

    Check engine scan tool, quick question...

    Can anyone help me understand the following from an Actron Elite AutoScanner (Advance Auto tool)? I tried Googling, searching the forum, and searching the user manual for the tool itself but still have some questions. HISTORY "MIL NOT REQUESTED" (does this mean the specific error has been...
  16. John03Z71

    Misfires and visible spark outside rubber plug boot

    Y’all were right, I just pulled the plug and sure enough it’s cracked all to hell. Popped the new one in and took it for a test drive, now purring smoother than ever. Many thanks to all for your input and suggestions!!
  17. John03Z71

    Misfires and visible spark outside rubber plug boot

    No, I have not taken the plug out to inspect it but I can try to do that this evening. The only thing that concerns me is that this problem (snapping sound with simultaneous engine misfiring at idle, and stumbling on acceleration) still existed before I swapped the plugs and wires, it's just...
  18. John03Z71

    Misfires and visible spark outside rubber plug boot

    I have an 03 Tahoe Z71 5.3 that has been running a bit rough for quite some time. When I say a bit, I mean a few misses when idling, slight hesitation when accelerating before normal performance, shuddering/shaking randomly on and off when stopped in traffic or at red lights. Enough to be...
  19. John03Z71

    Help me find this oil leak please!

    Yes, if you scroll up a handful of posts it turned out to be my rear main. I popped the inspection cover off the flywheel and it appeared mostly dry but a reputable shop pointed out some oil collecting around the bottom/inside area and others that weren’t so easy to spot at first glance. I...
  20. John03Z71

    Help me find this oil leak please!

    Thanks for the input. What other symptoms would be present if cats were clogged? Idle has been a bit rough and also fast/heavy acceleration, without flooring it (staying in same gear), is pretty sluggish and “jerky”, especially noticed it this summer when a/c compressor would be on it would be...
  21. John03Z71

    Help me find this oil leak please!

    I had a check engine light a couple weeks ago that stayed on for about 3 days then went off, hasn't come back on since. I did check the crank sensor behind the starter, no leaks there.
  22. John03Z71

    Help me find this oil leak please!

    Just had the rear main seal job finished up this morning. My BAD oil leak is gone (the drop every couple seconds off the starter and where bellhousing meets oil pan), now it’s just leaking a drop every minute or two from the same place, so am glad the rear main solved the bulk of the leak...
  23. John03Z71

    Help me find this oil leak please!

    Thanks all. Had it diagnosed by a very reputable shop today as the rear main seal. Sucks......
  24. John03Z71

    Help me find this oil leak please!

    So I spent over an hour last night getting dirty trying to find the leak with zero luck. First thing I did was pull the starter off, since I dried everything up the night before and the very first drips started forming on the starter bolt closest to the block. Crankshaft position sensor...
  25. John03Z71

    Help me find this oil leak please!

    Thanks. I did replace the oil pressure sending unit about 3-4 years ago, is it common for them to fail again like this? When I replaced it before it was due to the gauge reading way too high pressure, no leaking. Also I reached my hand way back there last night and felt all around but didn’t...

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