06-30-2014, 01:10 PM | #1 |
M6 9 second club
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L99 with low compression on AFM cyls only
2011 L99 completely stock internals with Maggie, 9psi, headers, rotofab, and solo catback
While on road course one of the h/f cats collapsed completely and car started running bad. cruised it home and started checking it for problems and ultimately found the bad cat. It drove normal at cruise only ran bad under load. Gutted cats, still ran bad........ Checked plugs, wires, injectors and compression etc Found #6 low only 50 psi Pulled head and piston was broken/cracked (same side as bad cat) Replaced piston, rod, rings for cyl 6 Went ahead and eliminated afm lifters, installed all new ls3 lifters and trays, valley cover from Magnuson for LS3, new o rings and gasket from dealer. Cleaned out oil pan, screen etc (skirt had broken off piston also) AFM was already turned off in tune. Also installed new plugs and wires Stock vvt cam was left unchanged. Car still runs bad. We turned on misfire counters in the tune and found all afm cylinders misfiring intermittently. Checked compression again, all afm cylinders are at 150ish and all non afm cylinders are 190-200. So obviously this is the problem, But my question is what could cause this only on those cylinders? All valves, pistons, etc visually looked good and compression was pretty equal before piston was changed.(maybe all cylinders within 15 psi of each other, don't remember the exact numbers Any ideas? Im starting to think rings are bad just doesn't make sense that's its on those 4 cyl only.
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06-30-2014, 07:56 PM | #2 |
COTW 5/06/2013
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cam is probably an issue, vvt function is operated by oil in the front of the cam, I would go with the cam first. , potentially causing a premature valve to open. then check to make sure all valves are sealing and not leaking
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2017 Grand Sport, Borla X Pipe.....Enough Said
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07-01-2014, 01:39 PM | #3 |
Drives: 2013 A6 GT 5.0 Join Date: Nov 2009
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Can the stock AFM cam even be used with LS7 lifters? Also why not change to a small VVT cam with out AFM?
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07-01-2014, 02:28 PM | #4 |
Drives: 416 w/TH400 Join Date: Mar 2012
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did you do a leak down test?
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07-01-2014, 02:39 PM | #5 |
Svt lol
Drives: 2011 ss inferno orange blown Join Date: Jan 2012
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Just delete all that crap, swap out the cam and front cover so you won't run into issues also if you start to swap things out, if you haven't already, turn off the dod setting in the tune. You're computer is probably confused as to why parts aren't in working together and firing as if there're all l99 parts in there.
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plasti dip is not a mod.......and a cold air intake doesn't make you fast!
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07-01-2014, 03:33 PM | #6 | |
Drives: 2010 RS/SS Join Date: Dec 2010
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Quote:
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07-01-2014, 03:53 PM | #7 | |||
M6 9 second club
Drives: A 4000 Lb BeaSSt Join Date: Jul 2009
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Quote:
Cam was left in due to budget constraints. Lifters were swapped out because heads were already off to check all Pistons so it made sense to swap lifters since a cam was in the future plans. I just don't think anybody has ever done the lifter swap on stock cam. gonna try that but its still at 150-160 compression so I doubt that will help. But I will ck compression on the cylinder with new piston and rod which is a afm cylinder. If that one is low, then I know for sure the piston or rings is not the issue since those are new. Quote:
Quote:
Sent from J-Rod's Continuum Transfunctioner
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TEAM LS3 Best pass: 9.61 @ 146 with M6
TBDRWHP TBDRWTQ ECS S/C 408, YSi, m6, Mantic Triple, ZL1 diff #BuiltByJRod.... J-Rod's Speed Shop.... Tuned by: Matt Sorian @ MS Tuning Check out my youtube channel: http://www.youtube.com/user/6410Jrod Follow me on Instagram: @J_Rod6410 |
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07-01-2014, 06:34 PM | #8 |
Svt lol
Drives: 2011 ss inferno orange blown Join Date: Jan 2012
Location: Topeka
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Swap the cam you'll be good to go.
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plasti dip is not a mod.......and a cold air intake doesn't make you fast!
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07-01-2014, 07:01 PM | #9 |
Drives: Bitches Crazy Join Date: Dec 2011
Location: Houston
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2011 2SS Convertible Black on Black on Black, Magnuson TVS2300 Supercharger, LS3 Conversion, LS9 Cam, Kooks Ceramic Coated Headers, LS3 Exhaust, Roto-Fab CAI, BMR Sway Bars and Bushings, JDP Color Changing Halos with Synced Grill Lighting, Custom Magnetic Removable Front Plate *** RECORD HOLDER - FASTEST 3 WHEELED, 7 CYLINDER CAMARO LAP TIME AT MSR *** |
07-02-2014, 08:11 AM | #10 |
Drives: Camaro Join Date: Jun 2014
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You're computer is probably confused as to why parts aren't in working together and firing as if there're all l99 parts in there.
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07-02-2014, 03:23 PM | #11 | |
M6 9 second club
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Yeah got an LS9 cam on the way
Quote:
Sent from J-Rod's Continuum Transfunctioner
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TEAM LS3 Best pass: 9.61 @ 146 with M6
TBDRWHP TBDRWTQ ECS S/C 408, YSi, m6, Mantic Triple, ZL1 diff #BuiltByJRod.... J-Rod's Speed Shop.... Tuned by: Matt Sorian @ MS Tuning Check out my youtube channel: http://www.youtube.com/user/6410Jrod Follow me on Instagram: @J_Rod6410 |
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07-05-2014, 12:41 PM | #12 |
M6 9 second club
Drives: A 4000 Lb BeaSSt Join Date: Jul 2009
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LS9 cam is in, VVT crap is removed.
All cylinders are equal compression now and Matt is working on the tune. Sent from J-Rod's Continuum Transfunctioner
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TEAM LS3 Best pass: 9.61 @ 146 with M6
TBDRWHP TBDRWTQ ECS S/C 408, YSi, m6, Mantic Triple, ZL1 diff #BuiltByJRod.... J-Rod's Speed Shop.... Tuned by: Matt Sorian @ MS Tuning Check out my youtube channel: http://www.youtube.com/user/6410Jrod Follow me on Instagram: @J_Rod6410 |
07-06-2014, 12:48 AM | #13 |
Drives: Bitches Crazy Join Date: Dec 2011
Location: Houston
Posts: 142
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L99 with low compression on AFM cyls only
All went well in the end. Was misfiring on a few cylinders on the dyno. Still had pieces of the melted cats in the muffler. Swapped the Solo catback for a stock LS3 catback and it cleared up. Made 500/480 on last pull. Needs a MSD BAP adjustment so it may have a few more horses in it.
www.h-towncamaroclub.com
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2011 2SS Convertible Black on Black on Black, Magnuson TVS2300 Supercharger, LS3 Conversion, LS9 Cam, Kooks Ceramic Coated Headers, LS3 Exhaust, Roto-Fab CAI, BMR Sway Bars and Bushings, JDP Color Changing Halos with Synced Grill Lighting, Custom Magnetic Removable Front Plate *** RECORD HOLDER - FASTEST 3 WHEELED, 7 CYLINDER CAMARO LAP TIME AT MSR *** |
07-06-2014, 08:02 AM | #14 |
Svt lol
Drives: 2011 ss inferno orange blown Join Date: Jan 2012
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Sweet glad it worked out and nothing broke internally.
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plasti dip is not a mod.......and a cold air intake doesn't make you fast!
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