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  • LS engine miss

    My 6.0 in my trailblazer, I'm staring to fill a misfire when setting cruise. I put my scanner on it and watched it on my way to work and it is #7 and sometimes #3. I'm going to put a set of AC plugs in it and thought about changing the coils. My thoughts....Do coils need changed a set at a time or can you replace just one and everything fine. Also anybody have and luck or can feel differences on aftermarket coils? Would like accel improve performance or do they have it pretty well figured out with the stock ones?

    Info if needed: Mines a 01 cast engine in a 05 trailblazer. 6.0 shortblock 5.3 heads and intake.

  • #2
    I'd go for coils/wires too. Those cyls being driver side.. not common to misfire.
    if right bank o2 is taking over, that may be rich on the left.

    the stock coils are the super versions, don't get much better.
    I'd be one to play with aftermarket anyway.

    A good plug wire at least.
    Any codes at all adds fuel, someone may lie to you and tell you different...only dominoes a firing problem.

    edit:
    come to think of my own errors, (but not full misfire) levelling off...
    it was hints the fuel pump was on its way out. Lost it eventually.
    Last edited by Barry Donovan; July 29, 2015, 07:17 AM.
    Previously boxer3main
    the death rate and fairy tales cannot kill the nature left behind.

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    • #3
      Its not throwing an codes but my scanner shows when it does it. I still dont have it fully tuned where it needs to be either. Next week I'll be going in for my 4th tune to play around with it. Its hard when no one around had a dyno to really know what is going on. I changed the gears from 3.42 to 3.73 and that gave it a boost also. The next tune we fo we gotta lower the speedo reading 10mph

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      • #4
        I'd move the plug wires around (like two cylinders over) and see if your mis-fire tracks with them. That's assuming you don't find any obvious burn marks or damage on the two suspected cylinder ones. You can change them individually and I'd stick with OE replacement ones instead of the aftermarket.
        Escaped on a technicality.

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        • #5
          definitely, move coils to see if the misfire follows the coil. pressure cleaning the injectors would be next. As far as changing them, I dont think you need to, its just deciding whether these are at the end of their life so the other 6 might soon follow. Injectors is a do them all deal when you are pulling the top of the engine off to get to them. Pretty sure yours are pretty easy to get to, at least my 6.0 in the 03 are, but same deal as the coils, they fire often and work alot, gotta be a life cycle to them..
          Last edited by anotheridiot; July 29, 2015, 07:52 AM.

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          • #6
            had a friends who traced a LS misfire down to coolant leak. Since you swapped the short block could a gasket have ripped? just think outside the box before you go buy unneeded coils.
            Neal

            Drag Week 2010, 2011, 2012, 2013

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            • #7
              Good question.. Have no Idea. But I haven't lost any coolant. I think Im going to see what the plugs look like and prolly change anyways and buy new wires and go from there. I had the engine put in by a shop and he couldnt remember if he had changed the plugs or not. The wires have about 175,000 miles on them. If they are oringinal..so ill prolly change them also.
              Last edited by chevybuytroy; July 30, 2015, 07:29 AM.

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              • #8
                Just priced MSD coils...$490.00 for a 8. I dont know if I want to spend that much and possibly have no results on the "family car." The MSD wires are 80.00 so I'll prolly go that route

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                • #9
                  Originally posted by chevybuytroy View Post
                  Just priced MSD coils...$490.00 for a 8. I dont know if I want to spend that much and possibly have no results on the "family car." The MSD wires are 80.00 so I'll prolly go that route
                  try a search on here for Dieselgeek and MSD coil. I'm pretty sure I remember them testing and the GM coils were as good or better than the MSD coils...
                  Flying south, with a flock of bird dogs.

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                  • #10
                    Found it thanks!! Wow what happened where we dont get tech threads like that anymore?

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                    • #11
                      Randall told you to stick with stock coils...

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                      • #12
                        Originally posted by Deaf Bob View Post
                        Randall told you to stick with stock coils...

                        Yes... and looks like thats what im going to do. I just couldn't wrap my head around if there is aftermarket isn't that better sydrome..

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                        • #13
                          Was your trailblazer a 4.2 originally? Did you have to change the trans as well? I think I would like my Wife's TB if it had a 5.3 and suburban / silverardo front seats. I would do plugs and wires then get a set of used coils and replace as needed. (But I am a hack )
                          http://www.bangshift.com/forum/forum...-consolidation
                          1.54, 7.31 @ 94.14, 11.43 @ 118.95

                          PB 60' 1.49
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                          • #14
                            Originally posted by Russell View Post
                            Was your trailblazer a 4.2 originally? Did you have to change the trans as well? I think I would like my Wife's TB if it had a 5.3 and suburban / silverardo front seats. I would do plugs and wires then get a set of used coils and replace as needed. (But I am a hack )

                            Mine was orginally a 5.3 engine that spun a rod when I got it. If you got from a 4.2 you need to change the bellhsg on the trans (removable) But all else is the same. When my trans goes out on this one I'm going to put a 4.2 liter Torque converter in it for a higher stall. Mine is a 3rd row also. I wanted something I could take the family in and still pull a trailer no problem if need be.

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                            • #15
                              Try plugs and wires first. Those coils usually don't go bad, if they do - it's at WOT you will notice it first, not light load. It's not likely to be an injector, If plugs and wires don't fix the problem, I would then start moving coils around. Make sure your grounds to the cylinder head(s) are in place, that's where the coils are grounded. Needs to be on the head too, not intake or block.
                              www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

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