Thread: Backfire
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Old 07-15-2009, 06:34 PM   #2 (permalink)
The Atomic Ass
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Join Date: Oct 2008
Location: Mason, OH
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Overland - '24 Nissan Versa S 5MT
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Quote:
Originally Posted by chipsndukes View Post
Well, I just introduced myself, in the other section.
I am not new to ecomodding, I have been "lurking" for a while and trying my hand at saving fuel.

I wanted to post, because something interesting happened yesterday:

I was driving out of a tight curve with the engine off, bumped it on a short straight and then shut down again for a tight left-hander.
It was uphill, and with someone behind me, I quick bumped the engine again...BOOM.

The person in front of me nearly stopped dead and I had to brake, the person behind me backed off. Nobody knew what happened, just that it was LOUD.

I know that it is possible to cause a backfire because of raw fuel in the exhaust system, but I thought that wouldn't happen, because when the ignition is turned off, the injectors close, right?

In 1 1/2 years, this has never happened to me, but I thought I would kindly ask for your comments!

Chipsndukes
In a multi-cylinder engine, fuel can be injected into a cylinder prior to shut off, and the shut off happens prior to that same cylinder getting spark ignition. As a matter of fact, it's probably going to happen every single time, with 4 cylinders. Although it was probably the quick stop-start routine that allowed enough fuel to collect to cause the backfire.

I'd recommend installing a kill switch!
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