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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
What makes them POP, pop, ...?

I believe EFI dose not do this as much as fuel is more shut off on de-acceleration. CIS on the other hand dose not seem to have any provision to cut fuel.

Is it an AFR and or ignition timing that on overrun is to far off that it can not be ignited fully in the combustion chamber or at all.

Then the unburned fuel hits the hot exhaust and maybe even gets some added oxygen from up the tail pipe and bang.

Dose the de accel valve add air such that a better AFR is achieved or dose it more accurately help keep the metering arm from over-swinging such that it creates an un ignitable lean spot.

Might disconnecting the Vac-Retard at the pot help keep spark advanced with throttle lift such that ignition is not as late for more complete combustion in the combustion chamber and less unburnt fuel making it to the exhaust area?

Never really got my arms around this except that a more quiet exhaust helps cover it up.

I to like the effect most the time.

Sorry, got carried away again.
Old 10-11-2010, 02:34 PM
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