post #1 of Old 09-02-2002, 07:41 PM Thread Starter
NMullens
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Backfiring

My 258 doesnt seem to breathe too well. If the RPMs get high, a few moments later (as soon as I let off the gas) there is a huge backfire. It sounds like a shotgun. Any time I let off the gas and am not stopped there is a rumble in the exhaust. Does anyone have any ideas? Thanks. Nathan


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post #2 of Old 09-02-2002, 08:20 PM
OldJeepguy
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Re: Backfiring

Quote:
Originally posted by NMullens
My 258 doesnt seem to breathe too well. If the RPMs get high, a few moments later (as soon as I let off the gas) there is a huge backfire. It sounds like a shotgun. Any time I let off the gas and am not stopped there is a rumble in the exhaust. Does anyone have any ideas? Thanks. Nathan
Your Jeep is definately sucking air in from somewhere - most likely the exhaust manifold to head connection.
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post #3 of Old 09-03-2002, 07:49 PM Thread Starter
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Thanks. Is this something that could be solved by tightening loose manifold bolts?

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post #4 of Old 09-03-2002, 08:48 PM
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Quote:
Originally posted by NMullens
Thanks. Is this something that could be solved by tightening loose manifold bolts?
Sometimes but usually need to replace the gasket.
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post #5 of Old 09-04-2002, 06:15 PM Thread Starter
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That's strange because I just replaced the gaskets about a month ago and the Jeep hasn't been run much to break them in. Could they have been installed wrong? It's not that complicated is it or is there a break in time for new gaskets?
Thanks again JeepGuy.

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post #6 of Old 09-04-2002, 10:33 PM
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Check ALL the connections! Especially The joint between the pipe and the manifold. You may of damaged the doughnut while replacing the manifold gasket.
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post #7 of Old 09-05-2002, 03:05 PM
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Mine was doing that too! I thought it was through the exhaust being that I have headers and very short cherry bombs out the fenderwell, but I had the carb rebuilt for a bad powervalve. With that and a choke adjustment the backfiring when letting off the throttle was gone.

Just my $.02 worth though.

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post #8 of Old 09-05-2002, 06:43 PM Thread Starter
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Im not even sure what a powervalve is in the carb, I'll have to look that one up. Thanks for all the feedback though.

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