[Diy_efi] Ignition Timing

[Becker, Damon Damon]

I suppose I'm advocating relying on the knock sensor as little as
possible.  I realize the OEMs do this, but my aftermarket EMS might not
be capable of doing the same things as the OEM setup.  Besides, doesn't
that amount to a band aide on a poorly-done mapping job?  

As for the compensation maps, setting a map means holding all else
constant and making measurements relative to that map.  Since that's
difficult or impossible, you have to rely on theory and give a buffer.
So if the theory says 1 degree for ever 20 *C of intake charge, then
give it 2 degrees and call it good?  

Damon

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]
On Behalf Of Adam Wade
Sent: Tuesday, July 26, 2005 4:04 PM
To: diy_efi at diy-efi.org
Subject: RE: [Diy_efi] Ignition Timing

--- "Becker, Damon (Damon)" <damonb at avaya.com> wrote:

> Set MBT (by extapolation, I'm assuming) and let the knock sensing 
> system handle it?  I'm not sure that's a good way.  The reason I'm not

> sure is the knock sensor requires actual knock to happen before it can

> sense it and respond.  If this happens too much before the response, 
> then the knock might get quickly severe, right?

Except that response should happen within one or two cycles of the
engine.  Unless you suddenly transition to heavy knock without any
"in-between", it's terribly unlikely to damage your engine.  Many
factory turbocharged vehicles seem to use this strategy without issue.

> As for mapping every possible combination, you could map the combo you

> have that day and set the compensation maps to be conservative.

All of the things I mentioned are very dynamic during operation of the
vehicle.  I would expect it to be damned difficult to map every possible
combination to get as close to MBT as possible without knock.

> Beyond that, you would have to rely on the knock sensor.

I don't udnerstand what the problem would be with that.

| Honda GL500 Interstate (Slug)    Kawasaki Zephyr 550 (Daphne) |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |
| M/C Fuel Inj. Hndbk. @ Amazon.com -  http://tinyurl.com/6o3ze |


		
__________________________________
Yahoo! Mail for Mobile
Take Yahoo! Mail with you! Check email on your mobile phone. 
http://mobile.yahoo.com/learn/mail
_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://lists.diy-efi.org/mailman/listinfo/diy_efi