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Thread: Backfire from intake manifold

  1. #1
    Member VE HSV R8's Avatar
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    Default Backfire from intake manifold

    Hi all, so just finished installing new mild cam lifters oil pump timing chain and all relevant gaskets to my LS3 auto Clubsport,now I’ve sent it off to get tuned and all’s going well until it started backfiring through the intake manifold and had a bit of a miss at idle,so realised that I needed to change the plugs(oem to Tr6’s) and changed the leads (2die) and tested for vacuum leaks aswell (nothing).
    So back on the dyno,warmed up then started a pull rev’s got to 4800ish it started backfiring from the manifold..again, tuner made afew adjustments and ran again..same thing again,he reckons timing and fuel is good,we take it for a drive runs great pulls hard all the way to limiter afew times,so now just driving on freeway (speed limit 60mph) cruising in top gear floor it,it drops back two gears revs hard to 5500...bang!! Started backfiring again,we now don’t know what to do all try,so any ideas would be greatly appreciated
    Also sorry about the long drawn out story. Thank again for any help.

    Jeff
    Last edited by VE HSV R8; 06-12-2018 at 03:11 AM.
    08 HSV R8
    LS3 A6 with Camaro pan.
    3.45 truetrac,cradle inserts,
    Whiteline swaybars front & rear.
    AP Racing Brakes with QFM hex Pads all round.
    VCM OTR.
    Billet Catch Can.
    1 3/4" pacemaker extractors,200cell metal euroV cats.
    2 1/2" Manta exhaust.
    Current Mods; VCM 21 cam-217/225* 600/580 lift Crow Cams Double valve spring kit,Smith Bros trunnion bush set...425hp 450tq current tune by Shannon Summers TuneCorp,WA.Just been retuned on hub Dyno 446 hp 498tq
    Mods to come:3 exhaust,machined TB,more braided hoses
    12.6@110mph.

  2. #2
    Moderator, Retired -Ray-'s Avatar
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    Default

    My feeling is the cam was installed too far advanced. Was it checked when installed?
    Rest in Peace Charlie!

    Sold


    Just a GT


    Quote Originally Posted by RichsGreyGT View Post
    this site is hardcore modding central.

  3. #3
    Member VE HSV R8's Avatar
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    Yeah ended up installed dot to dot which degreed at 109* and suggested install was 111*
    08 HSV R8
    LS3 A6 with Camaro pan.
    3.45 truetrac,cradle inserts,
    Whiteline swaybars front & rear.
    AP Racing Brakes with QFM hex Pads all round.
    VCM OTR.
    Billet Catch Can.
    1 3/4" pacemaker extractors,200cell metal euroV cats.
    2 1/2" Manta exhaust.
    Current Mods; VCM 21 cam-217/225* 600/580 lift Crow Cams Double valve spring kit,Smith Bros trunnion bush set...425hp 450tq current tune by Shannon Summers TuneCorp,WA.Just been retuned on hub Dyno 446 hp 498tq
    Mods to come:3 exhaust,machined TB,more braided hoses
    12.6@110mph.

  4. #4
    Member VE HSV R8's Avatar
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    Pulled the plugs today and found that it is running really rich and I don’t know how this will affect it but it’s going back tomorrow to see what my tuner thinks.
    08 HSV R8
    LS3 A6 with Camaro pan.
    3.45 truetrac,cradle inserts,
    Whiteline swaybars front & rear.
    AP Racing Brakes with QFM hex Pads all round.
    VCM OTR.
    Billet Catch Can.
    1 3/4" pacemaker extractors,200cell metal euroV cats.
    2 1/2" Manta exhaust.
    Current Mods; VCM 21 cam-217/225* 600/580 lift Crow Cams Double valve spring kit,Smith Bros trunnion bush set...425hp 450tq current tune by Shannon Summers TuneCorp,WA.Just been retuned on hub Dyno 446 hp 498tq
    Mods to come:3 exhaust,machined TB,more braided hoses
    12.6@110mph.

  5. #5
    Moderator, Retired -Ray-'s Avatar
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    So the springs can't hold the intake valves closed?
    Rest in Peace Charlie!

    Sold


    Just a GT


    Quote Originally Posted by RichsGreyGT View Post
    this site is hardcore modding central.

  6. #6
    Member VE HSV R8's Avatar
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    Don’t know,I thought they’d be fine,duel springs 140 on the seat and 355 open
    08 HSV R8
    LS3 A6 with Camaro pan.
    3.45 truetrac,cradle inserts,
    Whiteline swaybars front & rear.
    AP Racing Brakes with QFM hex Pads all round.
    VCM OTR.
    Billet Catch Can.
    1 3/4" pacemaker extractors,200cell metal euroV cats.
    2 1/2" Manta exhaust.
    Current Mods; VCM 21 cam-217/225* 600/580 lift Crow Cams Double valve spring kit,Smith Bros trunnion bush set...425hp 450tq current tune by Shannon Summers TuneCorp,WA.Just been retuned on hub Dyno 446 hp 498tq
    Mods to come:3 exhaust,machined TB,more braided hoses
    12.6@110mph.

  7. #7
    VIP Member STL_G8GT's Avatar
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    Quote Originally Posted by VE HSV R8 View Post
    Dont know,I thought theyd be fine,duel springs 140 on the seat and 355 open
    I think what Ray is saying is that if the cam events are 2deg off, it's possible that the valve events aren't lining up correctly with fueling/spark events.
    2009 PBM G8 GT
    Pat G 218/226 & TSP Dual 660s, ARP Bits, DSteck Tuned, Magnacharger Chrome 2300 1:1, RCR Ported/Polished TB, Blower, & L92 Heads w/ LS3 intake valves, Smith Brothers Trunion Bushing Kit, ARH 1 7/8 Magnaflow MidMuff/Solo Axlebacks, RotoFab, VaporWorx PWM 1:1 fuel system, ID1050x injectors
    Mike Norris Motorsports Catchcan, AEM 30-4100, JHP Boost/Fuel Gauge Pod
    TSW Nurburgring Matte Gray 18" w/Nitto 555 & 555R, Satin Black SS Brembo Fronts, BMR Trailing Arms, Pedders Sway Bars, Whiteline Bushings
    Gloss Black Valve Covers, 6k HID, V6 Handles, Interior/License Plate LEDs, Debadged, Holden Black Trim, Polk Dxi, GXP diffusor, a few bits from Crazy Paul

    Originally Posted by TonyKarter
    Anyone who has ever worked on a car has been in your position, and sitting cross-legged on a concrete floor with a dim shop light is its own kind of hell... Chalk it up as one of the rites of passage.
    RIP Charlie - GRRRR8
    RIP Chris Wells - Panzer Leader

  8. #8
    Member VE HSV R8's Avatar
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    Makes sence,I’m seeing my tuner tomorrow so I’ll let him know and see what he says,looks like I may be doing some more work over the weekend.
    08 HSV R8
    LS3 A6 with Camaro pan.
    3.45 truetrac,cradle inserts,
    Whiteline swaybars front & rear.
    AP Racing Brakes with QFM hex Pads all round.
    VCM OTR.
    Billet Catch Can.
    1 3/4" pacemaker extractors,200cell metal euroV cats.
    2 1/2" Manta exhaust.
    Current Mods; VCM 21 cam-217/225* 600/580 lift Crow Cams Double valve spring kit,Smith Bros trunnion bush set...425hp 450tq current tune by Shannon Summers TuneCorp,WA.Just been retuned on hub Dyno 446 hp 498tq
    Mods to come:3 exhaust,machined TB,more braided hoses
    12.6@110mph.

  9. #9
    VIP Member STL_G8GT's Avatar
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    Quote Originally Posted by VE HSV R8 View Post
    Makes sence,Im seeing my tuner tomorrow so Ill let him know and see what he says,looks like I may be doing some more work over the weekend.
    Ask your tuner if he adjusted eoit based on your cam... There's a dsteck spreadsheet and guide posted over on hp tuners forum.
    2009 PBM G8 GT
    Pat G 218/226 & TSP Dual 660s, ARP Bits, DSteck Tuned, Magnacharger Chrome 2300 1:1, RCR Ported/Polished TB, Blower, & L92 Heads w/ LS3 intake valves, Smith Brothers Trunion Bushing Kit, ARH 1 7/8 Magnaflow MidMuff/Solo Axlebacks, RotoFab, VaporWorx PWM 1:1 fuel system, ID1050x injectors
    Mike Norris Motorsports Catchcan, AEM 30-4100, JHP Boost/Fuel Gauge Pod
    TSW Nurburgring Matte Gray 18" w/Nitto 555 & 555R, Satin Black SS Brembo Fronts, BMR Trailing Arms, Pedders Sway Bars, Whiteline Bushings
    Gloss Black Valve Covers, 6k HID, V6 Handles, Interior/License Plate LEDs, Debadged, Holden Black Trim, Polk Dxi, GXP diffusor, a few bits from Crazy Paul

    Originally Posted by TonyKarter
    Anyone who has ever worked on a car has been in your position, and sitting cross-legged on a concrete floor with a dim shop light is its own kind of hell... Chalk it up as one of the rites of passage.
    RIP Charlie - GRRRR8
    RIP Chris Wells - Panzer Leader

  10. #10
    Member VE HSV R8's Avatar
    Join Date
    Oct 2013
    Location
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    I’ll ask when i see him today,thanks ����
    08 HSV R8
    LS3 A6 with Camaro pan.
    3.45 truetrac,cradle inserts,
    Whiteline swaybars front & rear.
    AP Racing Brakes with QFM hex Pads all round.
    VCM OTR.
    Billet Catch Can.
    1 3/4" pacemaker extractors,200cell metal euroV cats.
    2 1/2" Manta exhaust.
    Current Mods; VCM 21 cam-217/225* 600/580 lift Crow Cams Double valve spring kit,Smith Bros trunnion bush set...425hp 450tq current tune by Shannon Summers TuneCorp,WA.Just been retuned on hub Dyno 446 hp 498tq
    Mods to come:3 exhaust,machined TB,more braided hoses
    12.6@110mph.

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