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Back Fire Underhood

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Old Jan 21, 2008 | 10:23 AM
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Default Back Fire Underhood

I'll try and make this a short story. A while back i changed the sparks on my truck, one of the new sparks was cracked and the truck was missing. on and off a couple of times during the missing i would get a loud pop from under the hood during acceleration. A release of pressure obviously from something. Now all the sparks have been replaced again by the new ones from the dealer. The missing has stopped but every now and then i am getting a back fire from under the hood. I have noticed that it happens when i am accelerating..let off the gas briefly for some reson... and then reapply the accelerater. It doesn't always happen when i do that but everytime it does thats what im doing. The pop is quit audiable and i can almost feel it. it feels like its coming from the drivers side of the engine. Any of you qualified guys got any advice.
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Old Jan 21, 2008 | 11:01 AM
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Thats an odd duck. I would check for a vacuum leak. Could be a lean miss.
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Old Jan 21, 2008 | 06:17 PM
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i would get a timing light and check ur timing cuz mine did that when i was 180 out on the distributer make sure the timing is right and all the sparks plugs wires are on the right spots
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Old Jan 26, 2008 | 01:46 AM
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What year do you have? If it is new enough to have the computer controled ignition system (no distributer) that would make a big difference.
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Old Jan 26, 2008 | 09:02 PM
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its a 2005, explain!
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Old Jan 26, 2008 | 09:29 PM
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You do not have a distributor each plug has it's out ignition coil, and is fired by the engine management computer, and it can alter the timing of each plug. This is how these engines can run such a high compression ratio on lower octane fuel. knock censors can detect a knock coming on and the computer will alter the time of that cylinder to stop it. If you have a miss in particular cylinder, and you have ruled out a bad plug and or a back ignition cable look to the engine management computer.

Last edited by transmaster; Jan 26, 2008 at 09:39 PM.
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