Back firing through exhaust

1991 BUICK REGAL
89,000 MILES • 3.8L • 6 CYL • FWD • AUTOMATIC
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THEODORE SHAUGHNESSY
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Under a load such as taking off from a stop or going uphill car back fires through the exhaust. I replaced plugs, wires, coil pack and coil pack module and exhaust from manifold back and I am afraid of blowing out the new exhaust which will void the warranty. still having the same problem. Any help would be greatly appreciated.
Feb 18, 2017 at 2:23 PM
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STRAILER
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Hi THEODORE,

It sounds like you may have a broken valve spring that is not returning the valve to the closed potion under load. Also I would do a fuel pressure test to make sure enough fuel is entering the engine. Here are a couple of guides that will give you more of idea what to look for and how to fix it.

https://www.2carpros.com/articles/engine-backfires-while-running

and

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Please run some tests and get back to us so we can continue helping you.

Best, Ken
Feb 20, 2017 at 10:50 AM