LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Reading my spark plugs

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Old Feb 4, 2007 | 10:35 PM
  #1  
archangelus2's Avatar
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Question Reading my spark plugs

I was wondering if you guys could take a look at my plugs and give any recommendations/critiques you might have.

Brief History:
  • -7000 miles: Replaced Head Gasket, Plugs (NGK TR-55), Wires
  • -2000: Replaced Plugs again (Platinum AC Delco's)
  • Idle is a little shaky
  • Slight misfire after startup
  • Scantron reads long term fuel trims from 114(idle) to 128(slight accel)
  • Slow coolant leak
  • Idle likes to hover around 1500 until Coming down to proper rpm

I am currently fixing a header slip-tube leak and rebuilding throttle body, should be finished in a few days. 2000 miles ago plug 7 was arcing very badly on itself and I had all the plugs replaced. Ran good for about 2 weeks or so. If you look at plug 7 I have circled what appears to be "splash", did some reading and supposedly this is caused by misfire, fuel injectors or old carbon flung off after installing new plugs.

Ideas so far:
  1. Check the rest of the plugs
  2. seafoam the car (never done it before)
  3. Replace plugs
  4. Test fuel injectors? (no clue how this is done)
  5. Compression test
  6. Re-adjust Rocker arms with engine running
  7. Opti, ICM, Coil....

If you have anything to add or modify I would greatly appreciate it.
Thanks,

-Gabriel





Old Feb 5, 2007 | 12:15 AM
  #2  
SS RRR's Avatar
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From: Jackstandican
Originally Posted by archangelus2
[*]Slow coolant leak
Where's it at?
Old Feb 5, 2007 | 12:59 AM
  #3  
archangelus2's Avatar
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Posts: 66
Honestly I don't know where the coolant leak is at. It doesn't seem to be from anywhere obvious, I don't find any coolant under my car or anything. My oil color is good (not milk chocolate). My exhaust does put out a little bit of smoke at full throttle but I thought that was normal? I was thinking about trying to pressurize the radiator to see if something sprung a leak as was suggested on here before. I'm just not sure how to go about finding the leak so I have put off addressing the issue.
Old Feb 5, 2007 | 02:39 AM
  #4  
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From: Jackstandican
Check all your plugs and see if one is cleaner than all the others. If you don't have an external coolant leak and your coolant level is down then it's highly likely a head gasket has let go. Even if your oil checks out good you can still have a broken gasket that leaks from one of the water jackets into the cylinder. Keep track of what spark plug was pulled from the cylinders.
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