After fire on deceleration

[SirRobyn0]

I'm going to try to give my take on the "pops out the exhaust on deceleration"

Is it normal. No.

There are tons of possible causes. Ignition timing, fire getting past one or more exhaust valves, a little to rich, and the thing there is under deceleration vacuum goes up and that can increase the richness of the mixture just enough. Diverter valve on air pump, exhaust manifold leak.

My experience is that some mild popping while it can be annoying it isn't to much to worry about unless it starts to get to where it wants to actually backfire.

My two truck.
First one 1992 Dodge Dakota 3.9L fuel injected. I got this truck it was right around 200K, it's over 400K today. If I'm in a situation where I'm using a little bit of engine braking it'll pop a little. Has never progressed or changed.

My 1984 C20 305 - smog pump equipped truck does it a little more than the Dakota does but it's just kind of there. Pretty much will only happen if I'm using engine braking or step on the gas hard and suddenly release it. In my case it's fully factory as far as emissions stuff is concerned, but the PO put an Edelbrock on it so no decel valve and that could well be the cause.

I guess my point is I wouldn't get overly concerned as long as it's occasional mild popping. Now if it's like at the speed of popping popcorn that's a lot of popping and should be investigated, my trucks it's like one pop every second or two.

Those are my thoughts anyway.

 

[DoubleDingo]

Found a pic.

Thanks. Last night the truck decided it was going to begin running like crap, so I now have much more work before I can check for leaks and other causes of backfires.

 

[zac1981c20]

Apologies for the late response. The popping is like popcorn when driving anything over 35 when I just let off the gas it will pop in N if you rev up the truck hot or cold the timing and plugs Im not sure on the timing plugs are at .035 I believe. The reverse light I’m not sure I’ve never checked them to be honest. I plan on fixing the leaks soon once I get some better weather since the truck does not fit in my garage I crawled under the truck the other day and saw one bolt and nut missing from each side connections to the manifolds could that alone make it like popcorn?

 

[SirRobyn0]

Apologies for the late response. The popping is like popcorn when driving anything over 35 when I just let off the gas it will pop in N if you rev up the truck hot or cold the timing and plugs Im not sure on the timing plugs are at .035 I believe. The reverse light I’m not sure I’ve never checked them to be honest. I plan on fixing the leaks soon once I get some better weather since the truck does not fit in my garage I crawled under the truck the other day and saw one bolt and nut missing from each side connections to the manifolds could that alone make it like popcorn?

Exhaust leaks at the manifold can cause that. But if the missing bolt have allowed leakage for sometime then it's likely the gasket is bad.