ignition timing during off throttle decel

FlashPro questions & answers specific to the 2006-2009 (US, UK, Asia) S2000
Post Reply
shind3
Posts: 113
Joined: Mon Jun 30, 2014 8:02 am
Location: Pittsburgh, PA

ignition timing during off throttle decel

Post by shind3 »

Can you guys expose this table? I noticed a rough transition in my car is due to a rapid change in ignition timing between on and off throttle. When deceling off throttle, the timing drops down to about 23 degrees but applying very light throttle just enough to make it come out of 'idle mode' makes this jump up to 37 degrees. This is very noticeable.

In the Subaru world, I set this to the same value as the very left of the timing table so the transition between on/off throttle is smooth.

Thanks.

User avatar
Hondata
Site Admin
Posts: 9278
Joined: Thu Aug 15, 2002 12:13 pm
Location: Torrance, CA
Contact:

Re: ignition timing during off throttle decel

Post by Hondata »

I do not believe this is from ignition timing, but rather from the injector restart, unless these two events occur at different times. Post the calibration with a comment where the transition occurs.
Hondata

shind3
Posts: 113
Joined: Mon Jun 30, 2014 8:02 am
Location: Pittsburgh, PA

Re: ignition timing during off throttle decel

Post by shind3 »

It's a completely stock calibration. I haven't received my Hondata yet but I'm logging timing through an OBD2 logger.

Both the injector turning on and ramp up in timing occur the moment the throttle pedal is increased enough to come out of decel mode when above the fuel cut RPM. Injectors turn on and timing goes from 23 degrees to 37 at around 3000RPM. There is a table that defines what the ignition timing is when in off throttle decel. During this, the main timing map is ignored and a lower value is used to aid engine braking.

shind3
Posts: 113
Joined: Mon Jun 30, 2014 8:02 am
Location: Pittsburgh, PA

Re: ignition timing during off throttle decel

Post by shind3 »

OK, got my FlashPro and datalogged what I'm talking about. You can see both the injectors coming on and the ignition timing shooting up once you come out of overrun mode.
Attachments
Shek 70mm TP, 01.fpcal
(8.25 KiB) Downloaded 183 times
Shek 70mm TP, 01-140814-204354.fpdl
(3.28 KiB) Downloaded 182 times

User avatar
Hondata
Site Admin
Posts: 9278
Joined: Thu Aug 15, 2002 12:13 pm
Location: Torrance, CA
Contact:

Re: ignition timing during off throttle decel

Post by Hondata »

The lower ignition timing is not used for engine braking; upon overrun it doesn't matter what the timing is. The jerk is from the injectors restarting.
Hondata

shind3
Posts: 113
Joined: Mon Jun 30, 2014 8:02 am
Location: Pittsburgh, PA

Re: ignition timing during off throttle decel

Post by shind3 »

Ok. Thanks for your input. I won't worry about it then.

Post Reply