Hiccup on decel at 1700 rpm

[ron c]

'04 RT

I know this hiccup (from a loss of spark or fuel) is normal but I wonder why? I understand it is emissions related. How does this

reduce emissions?

 

Regards, Ron

[dirtrider]

Evening Ron

 

It's kind of complicated.

 

It starts with removing the popping & gurgling in the exhaust on decel.

 

There are two ways to reduce or remove the post-firing in the exhaust on dropped throttle. In the old days there would be a means to really richen the mixture on dropped throttle (usually a vacuum diaphragm attached to a fuel richening means) that worked good but also caused a very rich exhaust on decel. That rich exhaust is bad for fuel economy but even worse for the catalytic converter integrity. It is a bit better for ridability on dropped throttle though.

 

When the catalytic converters came along they needed to be protected on decel & also the need for better fuel economy so shutting the fuel off on dropped throttle decel above about 1500 RPM's seemed like the prudent thing to do.