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03 cobra 5.3 tt misfire
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<blockquote data-quote="chrisquirk187" data-source="post: 12128663" data-attributes="member: 89837"><p>Ok guys Ill skip the ranting and raving about how frustrated I am and just get to the issue.</p><p></p><p>I have a brand new MMR Mod 1000 5.3l stroker. Heres the mods</p><p></p><p></p><p>MMR Street Mod 1000 4V Longblock (4V, 8 bolt, 9 to 1 Comp 14-20lbs of Boost) </p><p>Upgrade to Boss Block</p><p>Upgrade to Stroker</p><p>Upgrade to Race Bearings Rod and Main </p><p>PC001Piston Coating - Ceramic Dome, Teflon Skirt</p><p>Head Porting of Cylinder Heads (Stage 3)</p><p>Stage 3 turbo Cams 4V with Manley High Performance 4V Springs</p><p>Timing chains, lifters, Rockers, Tensioners</p><p>Mainstud kit for 4.6/5.4 Iron Block</p><p>Upgrade to Cometic Head Gaskets</p><p>MELLING High Performance Oil Pump w/Billet Gears</p><p>MMR Street/Strip Oil pan for 4.6/5.4 </p><p></p><p>I then added a non-compund Hellion 64mm ball bearing billet wheel twin turbo set up that has just been rebuilt from Work Turbochargers. </p><p></p><p>The car has Lethals 1000hp return fuel system, 80lb injectors, electric water pump, SCT BA-3000 MAF, and I converted to a built 4r70w auto from TCI.</p><p></p><p>HERES THE ISSUE:</p><p></p><p>after an 800 mile break in I changed the oil and returned the car to the shop for its 18lbs of boost tune and we noticed a bad break up above 4k rpm. Datalogging showed a misfire from cylinders 3&5. This missfire is at any rpm as long as I hold the throttle steady its there. </p><p></p><p>a/f for the test is about 11.7 and volts are about 13.5. This is a well respected shop so I know the tune work is on point. </p><p></p><p>The shop and I have been troubleshooting this for 2 weeks now with no solution. Heres what we have done:</p><p></p><p>Switched all the injectors around</p><p>Switched all the coil packs around</p><p>Replaced all the power wires to zero gauge </p><p>replaced the ccrm</p><p>replaced the ecu </p><p>replaced the crankshaft position sensor</p><p>replaced the camshaft position sensor</p><p>Put in NGK BR7E at .28</p><p>Put in NGK TR6 at .32, .28, and .24</p><p>put a whole separate tune in the car</p><p>Did a smoke test for boost leaks</p><p>did a compression test </p><p>pulled the engine harness and tested each wire for breaks </p><p>did a leak down</p><p>replaced trigger wheel</p><p>and probably a few more things im forgetting about..</p><p></p><p>The only correlation between cylinders 3 and 5 are the ECU and the trigger wheel as far as I know. </p><p></p><p></p><p>PLEASE PLEASE PLEASE someone have a solution.</p><p></p><p>Thanks guys.</p></blockquote><p></p>
[QUOTE="chrisquirk187, post: 12128663, member: 89837"] Ok guys Ill skip the ranting and raving about how frustrated I am and just get to the issue. I have a brand new MMR Mod 1000 5.3l stroker. Heres the mods MMR Street Mod 1000 4V Longblock (4V, 8 bolt, 9 to 1 Comp 14-20lbs of Boost) Upgrade to Boss Block Upgrade to Stroker Upgrade to Race Bearings Rod and Main PC001Piston Coating - Ceramic Dome, Teflon Skirt Head Porting of Cylinder Heads (Stage 3) Stage 3 turbo Cams 4V with Manley High Performance 4V Springs Timing chains, lifters, Rockers, Tensioners Mainstud kit for 4.6/5.4 Iron Block Upgrade to Cometic Head Gaskets MELLING High Performance Oil Pump w/Billet Gears MMR Street/Strip Oil pan for 4.6/5.4 I then added a non-compund Hellion 64mm ball bearing billet wheel twin turbo set up that has just been rebuilt from Work Turbochargers. The car has Lethals 1000hp return fuel system, 80lb injectors, electric water pump, SCT BA-3000 MAF, and I converted to a built 4r70w auto from TCI. HERES THE ISSUE: after an 800 mile break in I changed the oil and returned the car to the shop for its 18lbs of boost tune and we noticed a bad break up above 4k rpm. Datalogging showed a misfire from cylinders 3&5. This missfire is at any rpm as long as I hold the throttle steady its there. a/f for the test is about 11.7 and volts are about 13.5. This is a well respected shop so I know the tune work is on point. The shop and I have been troubleshooting this for 2 weeks now with no solution. Heres what we have done: Switched all the injectors around Switched all the coil packs around Replaced all the power wires to zero gauge replaced the ccrm replaced the ecu replaced the crankshaft position sensor replaced the camshaft position sensor Put in NGK BR7E at .28 Put in NGK TR6 at .32, .28, and .24 put a whole separate tune in the car Did a smoke test for boost leaks did a compression test pulled the engine harness and tested each wire for breaks did a leak down replaced trigger wheel and probably a few more things im forgetting about.. The only correlation between cylinders 3 and 5 are the ECU and the trigger wheel as far as I know. PLEASE PLEASE PLEASE someone have a solution. Thanks guys. [/QUOTE]
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