×

Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

Overrun ignition retard

MoTeC M1 Software Tutorial

Forum Posts

Courses

Blog

Tech Articles

Discussion and questions related to the course MoTeC M1 Software Tutorial

= Resolved threads

Author
3176 Views

Please explain why the ignition may be set to retard during overrun when there is no combustion.

Thanks

It helps to drag the engine speed down and smooths the transition when you come off the throttle, than if the timing was left in Normal and throttle was the only control.

It also helps generate pops and bands on the overrun if you want it.

I understand your first paragraph, but the second one not quite because for pops and bangs we would still need some fuel mixture in the exhaust, or is what you are saying that there is some residual unburnt fuel left from prior to the overrun shutoff event ?

Edit:

I just realized that the thread title should carry the term "during fuel shutoff" as well. Apologies if I have caused any confusion and thanks for the answers.

The residual fuel comes from the fuel film "puddle" being drawn through the engine and consumed.

that makes sense, thank you very much.

We usually reply within 12hrs (often sooner)

Need Help?

Need help choosing a course?

Experiencing website difficulties?

Or need to contact us for any other reason?