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Explosive start


adallak

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With the northstar a backfire is often the sign of a failing fuel pressure regulator; perhaps the 4.9L has similar symptoms. The backfire itself can be very bad for the intake, and should be avoided. Long term I would say yes it will get worse until you diagnose and repair.

Bruce

2023 Cadillac CT4-V Blackwing

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Thanks Bruce and Ranger, will check the FPR ASAP. I do check it from time to time, but probably need a closer look. Th ebackfire actually might be the reason the manifold developed a crack. :(

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The Northstar intake manifold has a handy little relief valve (or "door") that opens in the event of a backfire, thus saving your manifold from becoming plastic shrapnel. Surely the 4.9 has this as well? Anyone?

Pardon the ignorance, but I never owned a 4.9L.

Regards,

Warren

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The Northstar intake manifold has a handy little relief valve (or "door") that opens in the event of a backfire, thus saving your manifold from becoming plastic shrapnel. Surely the 4.9 has this as well? Anyone?

Pardon the ignorance, but I never owned a 4.9L.

Regards,

Warren

Thanks Warren. I guess a leaky injector can cause that too. I checked them recently and all the resistances were within specs though.

The saddest thing in life is wasted talent

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