[OT] Boom boom sound

[Bruce Plecan]

Too rich or too lean can cause the over run rumble.
On my GN (auto, EFI) the Decleration Fuel Cut Off is set at 14.7AFR, and
rumbles since the timing is 10 ATDC.   On the CCC carb'd regal the timing is
6d BTDC, and rumbles also.  Cause with so much vac, it pulls fuel thru the
idle channel.  With the stock small idle channel isn't an issue.
Tranny type has little to do with it.
Exhuast system design will also play a part
Bruce




> Look i'm young, don't have a degree in anything :) hell i carn't even
drive
> car yet, but i was just thinking, does this popping usually happen in
manual
> cars?
> I thought it happened when the engine was been over-spun by the gears in a
> manual transmission? Sort of like when you use engine brakeing.
> I've heard it happen in a lot of carburettor application, with the
throttle
> plate closed, and still a stong vacuum from the wheels spinning the engine
> fast, it would suck in more petrol than it could burn and run rich?
Combine
> that with a free, open exhaust, and you've got enough air to burn that
> richness?
> In an EFi application, would the EFI computer get confused from the amount
> of air being 'sucked in' Vs. the throttle position (closed) during engine
> braking?
> (more air is sucked in during engine brakeing with closed throttle,
because
> the engine is spinning faster powered by the momentum of the car?)
> It would see more air than it should getting into the engine, with a
closed
> throttle plate, and in a MAP system, would this create a really stong
> vacuum, and it would mis-calculate the engine and somehow make it run
rich?
> Thanks for reading, sorry if I just wasted your time with stuff you
already
> know.

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