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Backfire Issue

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Old Oct 24, 2008 | 08:08 PM
  #1  
zoomz's Avatar
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Burning Brakes
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Default Backfire Issue

What would make a motor backfire through the pipes at 5400 rpms in any gear ?

This stupid problem has been rearing its head for 6 weeks now .

It usaly happens at wot but has backfired at 3/4 throttle .

The local shop had it for 2 weeks and couldnt figure it out either .

Ive tried swaping out the MAF , Computer , crank sensor , cam sensor , ive checked the wiring harness for issues and replaced a couple falty wires , changed spark plugs , swapped coil packs , built a new fuel system .

The car was running great right before i spun a rod bearing ,, had the motor rebuilt by Shaker , reassembled the car and now i get a backfire every time i go 3/4 to full throttle .

The car runs great other wise and there are no typical signs of a problem .

A/f is 12.750ish right up to the time the car does this .

When the car backfires it stops the logging and the car shuts off and stumbles from 5400 down to 4000 rpms then trys to catchback up to itself but cant .

Im at a total loss here and will try anything i can to get over this issue .



HELP ! ! !
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Old Oct 25, 2008 | 11:56 AM
  #2  
Beer99C5@FastbirdPerf.com's Avatar
Beer99C5@FastbirdPerf.com
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St. Jude Donor '08
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Have you tried the Crank Relearn Procedure ????
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Old Oct 25, 2008 | 02:36 PM
  #3  
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Burning Brakes
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Originally Posted by Beer99C5@FastbirdPerf.com
Have you tried the Crank Relearn Procedure ????
Yes , no help .
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Old Oct 27, 2008 | 12:52 PM
  #4  
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tblu92
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St. Jude Donor '13-'14-'15
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Originally Posted by Beer99C5@FastbirdPerf.com
Have you tried the Crank Relearn Procedure ????
My guess exactly--I would otherwise say that it suggests an Ignition problem--either a plug-wire-coil-connector--
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Old Dec 27, 2008 | 06:03 PM
  #5  
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zoomz
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Burning Brakes
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From: Winter Springs Fla
Default

Always check the reluctor wheel even tho you have a brand new motor before putting everything together :/

Someone had dropped either the crank or the wheel when the motor was being built.





Lucky for me i was able to straighten it out and clean up the burrs .

Hopefully everything is in good working order now .
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Old Dec 27, 2008 | 08:12 PM
  #6  
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ouch, thats a tough one to find. so is it a new motor. or the problem just now showed up?
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Old Dec 27, 2008 | 10:24 PM
  #7  
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Burning Brakes
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From: Winter Springs Fla
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Fresh rebuild on the bottom end .
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